Professor, Department of Agronomy, College of Agriculture, Sardar ...... 16. Scott FM, Schroeder MR, Turrell FM. Botan. Gaz. 1948; 109:381-411. 17. Sexton R, Lewis ...... Jian-hua Yuxin M, David J, Mulla E, Gyles W, Randall A, Vetsch M et al.
Research Trends in Agriculture Sciences Volume - 10
Chief Editor Dr. R.K. Naresh Professor, Department of Agronomy, College of Agriculture, Sardar Vallabhbhai Patel Univ. of Agri & Tech, Meerut-250110, Uttar Pradesh, India
AkiNik Publications New Delhi
Published By: AkiNik Publications AkiNik Publications 169, C-11, Sector - 3, Rohini, Delhi-110085, India Toll Free (India) – 18001234070 Chief Editor: Dr. R. K. Naresh The author/publisher has attempted to trace and acknowledge the materials reproduced in this publication and apologize if permission and acknowledgements to publish in this form have not been given. If any material has not been acknowledged please write and let us know so that we may rectify it. © AkiNik Publications Pages: 162 ISBN: 978-93-5335-043-7 Price: ` 585/-
Contents Chapters 1. Sphagneticola trilobata (L.) Pruski: An Aromatic Invasive Agricultural Weed Abundant in Alpha-Pinene
Page No. 01-09
(Emmanuel E. Essien, Ime R. Ekanem, Roberta Ascrizzi and Guido Flamini)
2. Residue and Nutrient Management Perspectives in Conservation Agriculture
11-39
(R.K. Naresh, Vineet Kumar, Saurabh Tyagi, Kanti Tyagi and Sandeep Chaudhary)
3. Anatomical, Physiological and Hormonal Aspects of Abscission in Fruit Crops
41-53
(Kaluram, Tanushree Sahoo, and Swosti Debapriya Behera)
4. Antitranspirant and Super Absorbent: Uses and Response on Plant Life
55-78
(P.P. Pandey and M. Suman)
5. Role of Flavonoids like Green Tea, Citrus Fruits (Antioxidant)
79-91
(Anjali Dahiya, Ritu Khasa, Ritu Saini and Harnek Saini)
6. Soil Formation in Toposequences
93-103
(Prava Kiran Dash)
7. Sugarcane Based Cropping System and Their Agronomic Requirements 105-120 (Dr. Navnit Kumar and Dr. Geeta Kumari)
8. Smut of Pearl Millet: Current Status and Future Prospects
121-131
(Annie Khanna, Kushal Raj and Pooja Sangwan)
9. Decision Support Systems and Crop Simulation Models for Effective Nutrient Management 133-142 (D. Raja and Y. Balachandra)
10. On-the go Sensors for Recommendation of Fertilizers for Field Crops in Different Agro-Ecological Regions 143-162 (D. Raja and Y. Balachandra)
Chapter - 1 Sphagneticola trilobata (L.) Pruski: An Aromatic Invasive Agricultural Weed Abundant in AlphaPinene
Authors Emmanuel E. Essien Department of Chemistry, University of Uyo, Uyo, Nigeria Ime R. Ekanem Department of Science Laboratory and Technology, Akwa Ibom State Polytechnic, Ikot Osura, Nigeria Roberta Ascrizzi Dipartimento di Farmacia, University of Pisa, Via Bonanno, Pisa, Italy Guido Flamini Dipartimento di Farmacia, University of Pisa, Via Bonanno, Pisa, Italy
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Chapter - 1 Sphagneticola trilobata (L.) Pruski: An Aromatic Invasive Agricultural Weed Abundant in Alpha-Pinene Emmanuel E. Essien, Ime R. Ekanem, Roberta Ascrizzi and Guido Flamini
Abstract Sphagneticola trilobata (L.) Pruski (Asteraceae) is an essential oilbearing soil creeper, with ethnomedicinal claims. The chemical composition of the volatile metabolites of the leaves, stem, and flowers were analyzed by means of gas chromatography-mass spectrometry (GC-MS). A total of forty constituents were identified, accounting for 98.2-99.5% of the oils composition. The predominant compounds in the leaf oil were α-pinene (57.9%) and germacrene D (7.1%), while α-pinene characterized the stem (89.5%) and flower (95.8%) oils. S. trilobata is a natural rich source of αpinene, and can be exploited for further useful benefits. Keywords: Asteraceae, Sphagneticola trilobata, invasive weed, essential oil, alpha pinene 1.
Introduction
Wedelia, known with the scientific name Sphagneticola trilobata (L.) Pruski, (Syn. Wedelia trilobata, W. chinensis, W. carnosa, and W. paludosa), is a member of the Asteraceae family (formerly Compositae), the sunflower or daisy family (Figure 1). S. trilobata is a soil creeper, forms a thick carpet, and it is widely cultivated as an ornamental groundcover. However, it easily escapes from gardens and forms a dense ground cover, crowding out or preventing regeneration of other species. In plantations, it will compete with crops for nutrients, light and water, and reduce crop yields [1]. The genus, Wedelia, named in honor of George Wolfgang Wedel (1645-1721), Professor of Botany at Jena, Germany, comprises about 70 tropical and subtropical species. Though S. trilobata is the accepted name for this species, it is widely known as Wedelia trilobata. S. trilobata is a very attractive plant because of its nearly constant and prolific blooming [2]. S. trilobata is listed in the IUCN's “List of the world's 100 worst invasive species” [3]. Page | 3
Fig 1: Sphagneticola trilobata Plant
In folk medicine, S. trilobata is employed to treat colds, abdominal pains, backache, muscle cramps, rheumatism, wounds, sores, swellings, and arthritic painful joints [4, 5], and in the management of diabetes [6]. Research has shown that S. trilobata contains high amounts of diterpenes, eudesmanolide lactones and luteolin [6, 8] with a variety of biological activities, namely, antileishmaniasis, anti-trypanosomiasis, wound healing, and analgesic properties [9, 12]. Essential oils extracted from aromatic plants are valuable products, generally of complex composition comprising the volatile principles contained in the plant. Most constituents of oil belong to the large group of terpenes. α-Pinene is the major monoterpene of various species of coniferous trees, especially the pine essential oils, with a strong turpentine odor [13]. It has been widely used as a food-flavoring ingredient [14], and was approved as a food additive by the U.S. Food and Drug Administration [15]. This chemical constituent is an important raw material for industrial synthesis, and is used in mouthwashes, cough lozenges, cold and chest ointments. In addition, studies have attributed biological properties, including antimicrobial [16], hypertensive [17], antinociceptive [18], anti-inflammatory [19], and aromatherapy effects to α-pinene. However, literature on the volatile oils composition of S. trilobata is scanty. Some researchers have reported high content of α-pinene in its leaf (78.64%) and aerial parts essential oils (78.683.3%) [20, 22]. As an integral part of our systematic evaluation of the poorly studied aromatic flora of Nigeria [23], we here report, for the first time, the volatile constituents of S. trilobata leaves, stems, and flowers. 2. Materials and Methods 2.1 Plant Material and Extraction of Essential Oils The fresh young leaves, stems, and flowers of S. trilobata were collected within the vicinity of the University of Uyo campus, in October 2017. The voucher specimen (UU 11418) was deposited in the herbarium of the Department of Botany and Ecological Studies, University of Uyo. The Page | 4
essential oil was obtained by hydro-distillation (4 h) of the fresh leaves using a Clevenger-type apparatus. The oil was dried over anhydrous sodium sulfate and stored in a refrigerator (4°C) immediately after the estimation of the percentage yield. 2.2 Gas Chromatography-Mass Spectrometry Analyses (GC-EIMS) (GC-EIMS) analysis was performed with a Varian CP-3800 gas chromatograph, equipped with a DB-5 capillary column (30 m×0.25 mm; coating thickness, 0.25 μm) and a Varian Saturn 2000 ion trap mass detector. Analytical conditions: injector and transfer line temperatures 220 and 240 °C, respectively; oven temperature programmed from 60 to 240 °C at 3 °C/min; carrier gas helium at 1 ml/min; injection of 0.2 μL (10% hexane solution); split ratio of 1:30. Constituents identification was based on comparison of retention times with those of authentic samples; this implied comparing their LRI with the series of n-hydrocarbons and using computer matching against commercial (NIST 2014 and ADAMS 2007) and homemade library mass spectra (built up from pure substances and components of known oils and mass spectra literature data) [24, 25]. 3.
Results and Discussion
The leaves, stems, and flowers of S. trilobata afforded 0.20%, 0.18% and 0.22% of yellow aromatic oils, respectively. The essential oils composition of S. trilobata is presented in Table 1. Thirty eight (38), seventeen (17), and three (3) constituents were identified in the leaves, stems, and floral oils, respectively. α-Pinene, β-pinene, and limonene were common to the three oils of S. trilobata. A total of forty constituents were identified, accounting for 98.2-99.5% of the oils composition. The major components of the leaf volatile oil were α-pinene (57.9%) and germacrene D (7.1%), while α-pinene characterized the stem (89.5%) and flower (95.8%) oils. The percentage composition of classes of compounds in S. trilobata essential oils was dominated by monoterpene hydrocarbons (65.4%, 96.6% and 98.6%). Other classes were considerably less represented or characterized only one of the essential oils, i.e., oxygenated monoterpenes (0.1%, 0.3% and 0.0%), sesquiterpene hydrocarbons (22.1%, 0.8% and 0.0%), and oxygenated sesquiterpenes (11.9%, 0.5% and 0.0%) for leaves, stems and flowers, respectively. The abundance of α-pinene in the Nigerian sample makes the oils similar to previously reported essential oils of S. trilobata from India and Brazil [20, 22, 26]. Furthermore, de Silva et al. [26] showed that the content of the monoterpenes (α-pinene, α-phellandrene and limonene) increased from the Page | 5
mid-rainy season until the middle of the next dry season. In contrast, Verma et al. [22] observed no significant differences in composition of S. trilobata oil, in a similar study about seasonal variations, though maximum oil yield was obtained during the winter season. 4.
Conclusion
It is interesting to note that the essential oils of this invasive agricultural weed, S. trilobata, especially the floral oil, could be utilized as a potential source of the pharmaceutical and industrial molecule, α-pinene. Table 1: Volatile constituents of S. trilobata leaves, stems, and flowers Relative abundance (%)
Constituent
LRI
α-Thujene
933
0.3
-
-
α-Pinene
941
57.9
89.5
95.8
Camphene
955
0.4
0.8
-
Sabinene
977
1.8
2.1
-
β-Pinene
981
1.6
0.8
0.5
Leaves
Stems
Flowers
Myrcene
993
0.6
-
-
α-Phellandrene
1006
0.1
0.5
-
p-Cymene
1028
-
0.4
-
Limonene
1032
2.2
2.2
2.3
(Z)-β-Ocimene
1042
0.4
0.1
-
(E)-β-Ocimene
1052
0.1
0.1
-
γ-Terpinene
1063
-
0.1
-
4-Terpineol
1179
0.1
0.3
-
α -Copaene
1377
0.6
0.2
-
β-Bourbonene
1385
0.2
-
-
β-Cubebene
1391
0.3
-
-
β-Elemene
1392
0.1
-
-
β-Caryophyllene
1419
3.0
0.3
-
β-Copaene
1430
0.2
-
-
α-Humulene
1455
0.7
-
-
Alloaromadendrene
1461
0.2
-
-
β-Chamigrene
1476
0.9
-
-
Germacrene D
1482
7.1
0.1
-
Bicyclosesquiphellandrene
1491
0.4
-
-
Bicyclogermacrene
1496
6.2
-
-
α-Muurolene
1499
0.3
-
-
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Cubebol
1515
1.0
-
-
δ-Cadinene
1524
1.9
0.2
-
Germacrene D-4-ol
1575
0.4
-
-
Spathulenol
1577
1.7
0.2
-
Globulol
1584
0.6
-
-
Humulene epoxide II
1607
0.1
-
-
Humulane-1,6-diene-3-ol
1616
2.1
0.3
-
10-Epi-γ-Eudesmol
1622
0.4
-
-
1-Epi-Cubenol
1629
0.5
-
-
γ-Eudesmol
1632
0.2
-
-
τ-Cadinol
1641
0.8
-
-
α-Muurolol
1646
0.3
-
-
α-Cadinol
1653
1.1
-
-
Epi-α-Bisabolol
1686
Total identified LRI: Linear retention index on a DB5 column.
2.7
-
-
99.5
98.2
98.6
References 1.
Global Invasive Species Database. Species profile: Sphagneticola trilobata. http://www.iucngisd.org/gisd/species.php?sc=44. 8 June, 2018.
2.
Thamam RR. Wedelia trilobata: Daisy Invader of the Pacific Islands, IAS Technical Report 99/2. Institute of Applied Science, University of South Pacific, Suva, Fiji, 1999, 1-10.
3.
Global Invasive Species Database."100 of the World's Worst Invasive Alien Species". http://www.iucngisd.org/gisd/100_worst.php. 8 June, 2018.
4.
Arvigo R, Balik M. Rainforest Remedies, One Hundred Healing Herbs of Belize, USA: Lotus Press, Twin Lakes, WI, 1993.
5.
Coe FG, Anderson GJ. Screening of medicinal plants used by the Garifuna of eastern Nicaragua for bioactive compounds. Journal of Ethnopharmacology. 1996; 53:29-50.
6.
That QT, Jossang J, Jossang A, Kim PP, Jaureguiberry G. Wedelolides A and B: Novel sesquiterpene-lactones, (9R)-eudesman-9, 12-olides from Wedelia trilobata. Journal of Organic Chemistry. 2007; 72:71027105.
7.
Zhang YH, Liu MF, Ling TJ, Wei XY. Allelopathic sesquiterpene Page | 7
lactones from Wedelia trilobata. Journal of Tropical and Subtropical Botany. 2004; 12:533-537. 8.
Qiang Y, Dub DL, Chenc YJ, Gao K. ent-Kaurane diterpenes and further constituents from Wedelia trilobata. Helvetica Chimica Acta. 2011; 94:817-823.
9.
Brito S, Crescente O, Fernndez A, Coronado A, Rodriguez N. Efficacy of a kaurenic acid extracted from the Venezuelan plant Wedelia trilobata (Asteracea) against Leishmania (Viannia) braziliensis, Biomedicine. 2006; 26:180-87.
10. Batista R., Chiari E, Oliveira AB. Trypanosomicidal kaurane diterpenes from Wedelia paludosa. Planta Medica. 1999; 65:283-284. 11. Balekar N, Nakpheng T, Katkam NG, Srichana T. Wound healing activity of ent-kaura-9(11), 16-dien-19-oic acid isolated from Wedelia trilobata (L.) leaves. Phytomedicine. 2012; 19:1178-1184. 12. Mizokami SS, Arakwa NS, Ambrosio SR, Zarpelon AC, Casagrande R, Cunha TM et al. Kaurenoic acid from inhibits inflammatory pain: Effect on cytokine production and activation of the NO−Cyclic GMP−protein kinase G−ATP-sensitive potassium channel signaling pathway. Journal of Natural Products. 2012; 75:896-904. 13. Groot PDG, MacDonald L. Influence of enantiomers of α-pinene on the response of the red pine cone beetle, Conophthorus resinosae, to its pheromone pityol. Entomologic Experimentalis Applicata. 2002; 105:169-174. 14. Rivas SA, Lopes P, Barros AM, Costa D, Alviano C, Alviano D. Biological activities of α-pinene and β-pinene enantiomers. Molecules. 2012; 17:6305-6316. 15. FDA. Code of Federal Regulations Title 21. Food and Drug Administration, Washington, DC, 2015. 16. Gomes-Carneiro MR, Viana ME, Felzenszwalb I, Paumgartten FJ. Evaluation of beta-myrcene, alpha-terpinene and (+) and (-)-alphapinene in the Salmonella/microsome assay. Food and Chemical Toxicology. 2005; 43:247-252. 17. Kamal EH, Al-Ajmi MF, Abdullah Ma-B. Some cardiovascular effects of the dethymoquinonated Nigella sativa volatile oil and its major components α-pinene and p-cymene in rats. Saudi Pharmacy Journal. 2003; 11:104-110. Page | 8
18. Him A, Ozbek H, Turel I, Oner AC. Antinociceptive activity of alpha pinene and fenchone. Pharmacology Online. 2008; 3:363-369. 19. Orhan I, Küpeli E, Aslan M, Kartal M, Yesilada E. Bioassay-guided evaluation of anti-inflammatory and antinociceptive activities of pistachio, Pistacia vera L. Journal of Ethnopharmacology. 2006; 105:235-240. 20. Craveiro AA, Matos FJA, Alencar JW, Machado MIL, Krush A, Silva MGV. Volatile constituents of two Wedelia species. Journal of Essential Oil Research. 1993; 5:439-441. 21. Nirmal SA, Chavan MJ, Tambe VD, Jadhav RS, Ghogare PB, Bhalke RiD et al. Chemical composition and antimicrobial activity of essential oil of Wedelia trilobata leaves. Indian Journal of Natural Products. 2005; 21(3):33-35. 22. Verma RS, Padalia RC, Chauhan A, Sundaresan V. Essential oil composition of Sphagneticola trilobata (L.) Pruski from India. Journal of Essential Oil Research. 2014; 26(1):29-33. 23. Essien, EE, Thomas PS, Ascrizzi R, Setzer WN, Flamini G. Senna occidentalis (L.) Link and Senna hirsuta (L.) H. S. Irwin & Barneby: constituents of fruit essential oils and antimicrobial activity. Natural Product Research. DOI:10.1080/14786419.2018.1425842. 24. Davies NW. Gas chromatographic retention indices of monoterpenes and sesquiterpenes on methyl silicon and carbowax 20M phases. Journal of Chromatography. 1990; 503:1-24. 25. Adams RP. Identification of Essential Oil Components by Gas Chromatography-Mass Spectroscopy. Allured, Carol Stream, 1995. 26. da Silva CJ, Barbosa LCA, Demuner AJ, Montanari RM, Francino D, Meira RMSA et al. Chemical composition and histochemistry of Sphagneticola trilobata essential oil. Brazilian Journal of Pharmacognosy. 2012; 22:1-8.
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Chapter - 2 Residue and Nutrient Management Perspectives in Conservation Agriculture
Authors R.K. Naresh Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh, India Vineet Kumar Indian Institute of Farming System Research, Modipuram, Meerut, Uttar Pradesh, India Saurabh Tyagi Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh, India Kanti Tyagi Syngetia India Ltd. North SBU office Chandigarh, Punjab, India Sandeep Chaudhary Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh, India
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Chapter - 2 Residue and Nutrient Management Perspectives in Conservation Agriculture R.K. Naresh, Vineet Kumar, Saurabh Tyagi, Kanti Tyagi and Sandeep Chaudhary
Conservation agriculture (CA) technologies involve minimum soil disturbance, permanent soil cover through crop residues or cover crops, and crop rotations for achieving higher productivity. In India, efforts to develop, refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA. Particularly, tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains. There are more payoffs than trade-offs for adoption of CA but the equilibrium among the two was understood by both adopters and promoters. The technologies of CA provide opportunities to reduce the cost of production, save water and nutrients, increase yields, increase crop diversification, improve efficient use of resources, and benefit the environment. However, there are still constraints for promotion of CA technologies, such as lack of appropriate seeders especially for small and medium scale farmers, competition of crop residues between CA use and livestock feeding, burning of crop residues, availability of skilled and scientific manpower and overcoming the bias or mind-set about tillage. Human efforts to produce ever-greater amounts of food leave their mark on our environment. Persistent use of conventional farming practices based on extensive tillage, and especially when combined with in situ burning of crop residues, have increased soil erosion losses and the soil resource base has been steadily degraded. Nowadays, people have come to understand that agriculture should not only be high yielding, but also sustainable. Farmers concerned about the environmental sustain ability of their crop production systems con1bined with ever-increasing production costs have begun to adopt and adapt improved management practices which lead towards the ultimate vision of sustainable conservation agriculture. Conservation agriculture addresses a concept of the complete agricultural system, Page | 13
combining three basic principles (1) reduction in tillage, (2) retention of adequate levels of crop residues as surface cover of the soil and. (3) use of economically viable crop rotations. These conservation agriculture principles are applicable to a wide range of crop production systems. Obviously, specific and compatible management components will need to be identified through adaptive research with active farmer participation for contrasting agro-climatic/production systems. Conservation Agriculture (CA) systems aim at enhancing soil health and function as a precursor to sustainable production intensification. Nutrient management in CA must be formulated within this framework of soil health. Thus, nutrient management strategies in CA systems would need to attend to the following four general aspects, namely: (i) the biological processes of the soil e.g. soil biota, microorganisms and soil organic matter;(ii) soil organic biomass production and biological nitrogen fixation for keeping soil energy and nutrient stocks at adequate levels to support higher levels of biological activity, and crop residues for covering the soil; (iii) access to all nutrients by plant roots in the soil, from natural and fertilizer sources, to meet crop needs; and (iv) the soil acidity/alkalinity. Fundamentally, CA is underpinned by biologically-framed management practices, the so called 'second-paradigm approaches' as enunciated by Sanchez (1994). As such, soil organic matter and soil biota are essential components in the complex system of interactions related to soil health and crop productivity. They provide a basis for optimizing the use of inorganic soil amendments and plant nutrients so that there is a positive-sum effect on agricultural productivity and the environment. Since the second-paradigm approaches arc relatively new, limited systematic research has been done on how to harness the potentials of biologically-framed agricultural production systems. Soil health is the capacity of the soil to function as a living system in which soil biological processes or the endogenous inputs are utilised alongside any exogenous inputs required to achieve the desired level of agricultural production that is economically and environmentally sustainable. Thus, with CA systems, the establishment and maintenance of healthy soil condition is inextricably linked to the achievement of effective nutrient management. Soil Health and Conservation Agriculture For a soil to be productive for agricultural use, it must inter alia have the space for plant roots to grow, to hold and make water and nutrients available Page | 14
to plant roots, and provide a conducive biotic and chemical environment for soil microorganisms to function to maintain soil porosity, fix atmospheric nitrogen, hold and mineralize nutrients. All these dimensions must operate together and form the basis of soil health as defined. Soil health is the capacity of soil to function as a living system, with ecosystem and land use boundaries, to sustain plant and animal productivity, n1aintain or enhance water and air quality, and promote plant and animal health. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots (e.g., nitrogen-fixing bacteria and mycorrhizal fungi); recycle essential plant nutrients; improve soil structure (e.g., aggregate stability) with positive repercussions for soil water and nutrient holding capacity, and ultimately improve crop production. In many parts of the world soils are acknowledged to be sick, in poor health, and failing in potential for self-sustaining productivity. \While there is much talk of 'soil quality' as if it were a static and sufficient characteristic, there is lessfrequent mention of 'soil health', referring particularly to the biological dynamics of soil quality. Soil in 'good condition' (static) or 'good health' (dynamic) benefits from the following key components of CA: Minimum Disturbance of Optimum Porous Soil Architecture, Which Provides/Maintains: (a) Optimum proportions of respiration gases in the rooting-zone, (b) Moderates organic-matter oxidation; (c) Porosity to facilitate water movement, retention and release at all scales, and (d) Limits re-exposure of weed seeds and their germination. A Permanent Covering of Sufficient Organic Matter (Esp. Crop Residues) Over the Soil Surface Provides: (a) Buffering against severe impact of solar radiation and rain; (b) A substrate for soil organisms' activity; (c) Raised cation-exchange capacity for nutrient capture, retention and slowrelease; and (d) Smothering of weeds. Cropping sequences and rotations which include legumes, provide: (a) Minimal rates of build-up of populations of pest species, through life-cycle disruption; (b) Biological Nfixation in appropriate conditions, limiting external costs; (c) Prolonged slow-release of such N from con1plex organic molecules derived from soil organisms; (d) Range of species, for direct harvest and/or fodder; and (e) Soil profile improvement by organic-matter addition at all depths. Ministry of New and Renewable Energy (MNRE 2009), Govt. of India Page | 15
estimated that about 500 Mt of crop residue is generated every year. There is a large variability in crop residues generation and their use depending on the cropping intensity, productivity and crops grown in different states of India. Residue generation is highest in Uttar Pradesh (60 Mt) followed by Punjab (51 Mt) and Maharashtra (46 Mt). Among different crops, cereals generate 352 Mt residue followed by fibres (66 Mt), oilseed (29 Mt), pulses (13 Mt) and sugarcane (12 Mt). The cereal crops (rice, wheat, maize, millets) contribute 70% while rice crop alone contributes 34% of crop residues. Wheat ranks second with 22% of residues whereas fibre crops contribute 13% of residues generated from all crops. Among fibres, cotton generates maximum (53 Mt) with 11% of crop residues. Coconut ranks second among fibre crops with 12 Mt of residue generation. Sugarcane residues comprising tops and leaves generates 12 Mt i.e., 2% of crop residues in India. The surplus residues i.e., total residues generated fewer residues used for various purposes, are typically burned in the field or used to meet household energy needs by farmers. Estimated total crop residue surplus in India is 84-141 Mt yr-1 where cereals and fiber crops contribute 58% and 23%, respectively. Remaining 19% is from sugarcane, pulses, oilseeds and other crops. Out of 82 Mt surplus residues from the cereal crops, 44 Mt is from rice followed by 24.5 Mt of wheat which is mostly burned in fields. In case of fiber crops (33 Mt of surplus residue) approximately 80% is cotton residue that is subjected to burning. Beneficial Effects of Residues on Soil Health Incorporation of crop residues in soil or retention on surface has several positive influences on physical, chemical and biological properties of soil. It increases hydraulic conductivity and reduce bulk density of soil by modifying soil structure and aggregate stability. Mulching with plant residues raises the minimum soil temperature in winter due to reduction in upward heat flux from soil and decreases soil temperature during summer due to shading effect. Retention of crop residues on soil surface slows runoff by acting as tiny dams, reduces surface crust formation and enhances infiltration. The channels (macro-pores) created by earthworms and old plant roots, when left intact with no-till, improve infiltration to help reduce or eliminate runoff. Combined with reduced water evaporation from the top few inches of soil and with improved soil characteristics, higher level of soil moisture can contribute to higher crop yield in many cropping and climatic situations. Residues act as reservoir for plant nutrients, prevent leaching of Page | 16
nutrients, increase cation exchange capacity (CEC), provide congenial environment for biological N fixation, increase microbial biomass and enhance activities of enzymes such as dehydrogenase and alkaline phosphatase. Increased microbial biomass can enhance nutrients availability in soil as well as act as sink and source of plant nutrients. Leaving substantial amounts of crop residues evenly distributed over the soil surface reduces wind and water erosion, increases water infiltration and moisture retention, and reduces surface sediment and water runoff. The crop residues play an important role in amelioration of soil acidity through the release of hydroxyls especially during the decomposition of residues with higher C: N ratios and soil alkalinity through application of residues from lower C: N ratio crops including legumes: oilseeds and pulses. The role of crop residues on carbon sequestration in the soil would be an added advantage in relation to climate change effects management. Constraints of Using Residues in Conservation Agriculture A series of challenges exist with higher residue levels in Conservation Agriculture (CA). These include different disease, insect or weed problems and difficulties with more residues on the surface to proper seed, fertilizer and pesticide placement. Conservation tillage practices, with their higher levels of crop residue, usually require more attention, timing, placement of nutrients and pesticides and tillage operations. Nutrient management may become complex because of higher residue levels and reduced options with regard to method and timing of nutrient applications. No-till in particular can complicate manure application and may also contribute to nutrient stratification within soil profile from repeated surface applications without any mechanical incorporation. Major bottlenecks in the current technology that needs attention are placement of seed at proper depth to facilitate germination in the no-tilled plots with residue retained on the soil surface is still a problem. Although a lot of improvement has been done in the zero-till seed-cum-fertilizer drill machinery, but there is still a lot of scope for further improvement to give farmers a hassle free technology. Weed control is the other bottle-neck especially in rice-wheat system. Excessive use of chemical herbicides may not be desirable keeping in view their leakage to the environment. Applying all the fertilizers, especially N, as basal dose at the time of seeding, may result a loss in its efficiency, and cause environmental pollution. With higher residue levels, however, evaporation is reduced and more water is maintained near the surface, which favors the growth of feeder roots near the surface where the nutrients are concentrated. In some instances, increased Page | 17
application of specific nutrients may be necessary and specialized equipment required for proper fertilizer placement, thereby contributing to higher costs. Similarly, increased use of herbicides may become necessary for adopting CA. The countries that use relatively higher amount of herbicides are already facing problem of non-point source of pollution and environmental hazard. Further limiting factor in adoption of residue incorporation systems by farmers include additional management skill requirements, apprehension of lower crop yields and/or economic returns, negative attitudes or perceptions, and institutional constraints. Farmers or sometime the whole communities demonstrate strong preferences for clean tilled fields. Culturally, they take pride in having their fields "clean" of residue and intensively tilled to obtain a smooth surface in preparation for planting. Alternative Uses of Crop Residues There are several options which can be practiced to manage residues in productive manner. Besides use as cattle feed, large amount of residues can be used for preparation of compost, generation of energy and production of biofuel and mushroom cultivation. Composting of Residues for Manure The residues can be composted by using it as animal bedding and then heaping in dung pit. Each kg of straw absorbs about 2-3 kg of urine from the animal shed. It can also be composted by alternative methods on the farm itself. The residues of rice from one hectare give about 3.2 tons of manure as rich in nutrients as farmyard manure (FYM). Energy from Crop Residues Biomass can be efficiently utilized as a source of energy and is of interest worldwide because of its environmental advantages. During recent years, there has been an increase in the usage of crop residue for energy production and as substitute for fossil fuels. It also offers an immediate solution for the reduction of CO2 content in the atmosphere. In comparison with the other renewable energy resources such as solar and wind energy, biomass is a storable resource, inexpensive, energy efficient and environment friendly. However, straw is characterized by low bulk-density and low energy yield per weight basis. The logistics of transporting the large volumes of straw required for efficient energy generation represents a major cost factor irrespective of the bio-energy technology. Availability of residues, transport cost and infra-structural settings (harvest machinery, modes of collection, etc.) are some of the driving factors of using residues for energy generation. Page | 18
Ethanol from Crop Residues The conversion of ligno-cellulosic biomass into bio-based alcohol production is of immense importance and is a researchable issue as ethanol can be either blended with gasoline as a fuel extender and octane-enhancing agent or used as a neat fuel in internal combustion engines. The theoretical estimates of ethanol production from different feedstock (corn grain, rice straw, wheat straw, bagasse and saw dust) varies from 382 to 471 L t-1 of dry matter. Biomethanation Biomass such as rice straw can be converted to biogas, a mixture of carbon dioxide and methane and used as fuel. It is reported that biogas of 300 m3 t-1 of dry rice straw can be obtained. The process yields good quality of gas with 55-60% of methane and the spent slurry can be used as manure. This process promises a method to utilize crop residues in a non-destructive way to extract high quality fuel gas and produce manure to be recycled in soil. Gasification of Residues Gasification is a thermo-chemical process in which gas is formed due to partial combustion of residues. The process breaks down biomass completely to yield energy rich gaseous products after initial pyrolysis. The main problem in biomass gasification for power generation is the cleaning of gas so that impurities are removed. The residues can be used in the gasifiers for the generation of producer gas. In some states gasifiers with more than 1MW capacity has been installed for generation of producer gas which is fed to the engines coupled to the alternators for electricity generation. One ton of biomass can be used for generation of 300 kWh of electricity. Fast Pyrolysis Fast pyrolysis of crop residues requires the temperature of biomass to be raised to 400-500 oC within few seconds. This results in a remarkable change in the thermal disintegration process. About 75% of dry weight of biomass is converted into condensable vapours. If the condensate cools quickly within a couple of seconds, it yields a dark brown viscous liquid commonly called bio-oil. The calorific value of bio-oil varies 16-20 MJ kg-1. Biochar Biochar is high carbon material produced from the slow pyrolysis (heating in the absence of oxygen) of biomass. It has got advantages in terms Page | 19
of its efficiency as an energy source, its use as a fertilizer when mixed with soil, its ability to stabilize as well as reduce emissions of harmful gases in the atmosphere. Biochar finds use in the release of energy-rich gases which are then used for producing liquid fuels or directly for power and/or heat generation. It can potentially play a major role in the long-term storage of carbon. Biochar increases the fertility, water retention capability of the soil as well as increasing the rate of mineral delivery to roots of the plants. Elements of a Nutrient Management Strategy in CA Being a biologically-based practice with an agro-ecological perspective, CA does not focus on a single commodity or species. Instead, it addresses the complex interactions of several crops to particular local conditions capitalizing on the complex systems of interactions involved when managing soil systems productively and sustainably. Nutrient management strategies in CA systems would need to attend to the following four general aspects, namely: I.
The biological processes of the soil are enhanced and protected so that all the soil biota and micro-organisms are privileged and that soil organic matter and soil porosity are built up and maintained;
II. There is adequate biomass production and biological nitrogen fixation for keeping soil energy and nutrient stocks sufficient to support higher levels of biological activity, and for covering the soil; III. There is an adequate access to all nutrients by plant roots in the soil, from natural and synthetic sources, to meet crop needs; and IV. The soil pH is kept within acceptable range for all key soil chemical and biological processes to function effectively. Managing Soil Biological Processes-Soil as a Living System Plants, rivers and groundwater depend on water penetrating into soil which is porous from the surface downwards. Insufficiency of water for plants hinders the interacting functioning of the other components of soil productivity: biological, physical, and chemical. The rate of entry of water into and through and its movement within the soil is governed by soil's porosity, both micro and rnacro, which in turn is governed by the volume and inter-connectedness of pores to transmit water. The volume an availability of water which plants can use is determined by the proportion of soil pores which can retain water against the force of gravity and yet can release that water in response to 'suction' exerted through roots as dictated by Page | 20
the plants' physiology and atmospheric demand. Water management in soil is intrinsically linked to nutrient management. Insufficiency of water and/or of various nutrients required by plants for growth processes diminish the derived productivity of the soil in which they are growing, inhibiting full interactions in the plant-soil system. Inadequacy of plant nutrients hinders plant growth and development; severe water-stress stops the whole system. Soil porosity is damaged or destroyed by compaction, pulverization, and/or collapse due to degradation and loss of organic matter. Net loss of organic matter is caused by tillage of the soil which results in accelerated oxidation of the organic carbon in the materials to carbon dioxide gas and its loss to the atmosphere. Following such damages, appropriate soil porosity is regained and maintained chiefly through biotic transformation of the nonliving fraction of organic matter by its living fraction-soil-inhabiting fauna and flora - from micro-organisms such as bacteria to macro-organisms such as worms, termites and plants themselves. Their metabolic activity contributes glue-like substances, fungal hyphen, etc. to the formation of irregular aggregates of soil particles, within and between which are the all important pore-spaces in which water, oxygen and carbon dioxide flow and roots grow. These substances also contribute markedly to the soil's capacity to capture and retain nutrient ions on organic complexes, and provide a slow-release mechanism for their liberation back into the moisture in the soil For this activity and its effects to be unmaintained, a sufficient supply of new organic matter needs always to be available in the soil as a source of energy and nutrients to the soil organisms-not just to the plants alone. If the conditions are kept favorable for biotic activity in the soil, this dynamic process of formation and reformation of the porous soil architecture will continue from year to year, maintaining the capacities of landscapes thus treated to continue yielding vegetation and water on a recurrent basis, contributing to sustainability of such production processes. Here lies the Significance of maintaining 'soil health'. For the purposes of deciding how best to manage the land and nutrients to maintain its productivity, it is more appropriate to think of the soil primarily as a living porous biological entity interpenetrating the non-living components, and forming from the top downwards, rather than as a geological entity forming from the bottom upwards with living things in it at the top (Shaxson et aI., 2008). Managing Biomass Production and Biological Nitrogen Fixation CA systems require higher levels of biomass production within the Page | 21
rotation to develop and maintain an adequate mulch cover, to raise soil organic matter level, to enhance soil biodiversity and their functions, to raise moisture and nutrient holding capacities, to enhance nutrient supplies, to enrich the soil with nitrogen in the case of legumes, and to protect the soil surface. Practices that enhance soil organic matter are built into CA principles and include one or more of the following, including: minin1al or no-till; diversifying cropping systems; planting trees; mulching; using cover crops and green manures, using crop rotations; and using nitrogen fixing crops. Nitrogen is fixed from the atmosphere by all kinds of free living organisms in undisturbed soils, and also by rhizobia in root nodules in legume crops as well as in herbaceous and woody legumes. Soil organisms including protozoa and nematodes in the root rhizosphere also fix atmospheric nitrogen, and so the nitrogen cycle has multiple pathways to restore nitrogen to the soil and supply to crops. For crop growth and for soil microorganisms to function, and for soil organic matter to build up, adequate nitrogen supply is needed. No-till and planted fallows and pastures in the rotation can preserve soil integrity and soil organic matter, and various herbaceous and tree legumes can make a contribution to maintaining a positive nitrogen balance for the cropping system (Boddey et al. 2006). Equally, failure to compensate for any net nutrient outputs can lead to losses in soil organic matter and soil nutrient reserves in the short Turn, and to soil erosion and soil system degradation in the long term. Managing Access to a Balanced Nutrient Supply The more common notion regarding crop nutrition is based on maintaining overall quantities or concentrations of nutrients in the soil. At the practical level this is reduced to a simple output-input nutrient balance equation so that what is taken out by the crop is or must be replaced by application of nutrients from inorganic fertilizer or other sources. Invariably, this approach is combined with intensive soil tillage that reduces, over time, soil organic matter and porosity, and therefore also its water and nutrient holding capacity as well as all the beneficial soil biological processes. In a CA system, there is no compacted subsoil plough layer. Instead there is another type layer, a surface layer of mulch enriched with organic plant residues and nutrients, and altering the dynamics of the organic matter of the soil and the cycling and flows of nutrients (Seguy et al., 2006). In a sense, in CA systems, forest floor conditions are emulated and nutrient cycling through cover crops act as 'nutrient pumps' to enhance and conserve Page | 22
pools of nutrients from which plant roots feed. Nutrients are returned to the system via mulch mineralization, regulated by C: N ratio and lignin content of the aboveground and root parts of the crops. Much of the system's nutrients are held in the biomass in a semi-closed manner rather than in the soil. The continuous increase in surface and soil biomass and in soil biological processes in CA facilitate the formation and existence of a nutrient balance as proposed by Kinsey and which leads to crop plants that are healthier. At least 18 mineral nutrients are necessary for plant growth, and maintaining access to a balanced supply of nutrients to crops in CA system is clearly helped by the biologically-oriented processes in the system that has a higher level of biomass and soil organic matter. Organic soil amendments have the advantage of providing more or less a full range of nutrients in contrast to mineral fertilizers. Where there are likely to be serious deficiencies of mineral nutrients, these have to be corrected from the start to avoid disrupting the development of the soil biological processes. In a fully established CA system, the aim of fertilizer nutrient management is to maintain soil nutrient levels, replacing the losses resulting fron1 the nutrients exported by the crops. Because CA systems have diverse crop mix including legumes, and nutrients are stored in the soil organic matter, nutrients and their cycles must be managed more at the system or crop mix level. Thus, fertilization would not anymore be strictly crop specific, with the exception of nitrogen top dressing (if required at an), but win be given to the soil system at the most convenient time during the crop rotation. With the management of legume crops, either as previous crop in the rotation or as component in a cover crop before the next cash crop "top" dressing with nitrogen can be replaced by the N captured by the legumes and released during the following cropping cycle at the required time (more legume content - earlier release, more grass content in cover crop, later release). Additionally, undisturbed soils are habitats for free living nitrogen fixing bacteria and there is rhizospheric fixation of nitrogen. Managing Soil Acidity Soil pH is critical for several reasons. It has a major influence on the availability of elements, including primary nutrients like nitrogen, phosphorus and potassium, as well as secondary nutrients, micronutrients and potentially toxic elements like aluminum. Most soil microorganisms are sensitive to soil acidity, which has an influence on nutrient availability (especially nitrogen), soil organic matter and general soil health. The most Page | 23
beneficial soil fungi, for instance, do not like a high pH, and soil bacteria have problems at lower pH. One of the main reasons for managing soil pH by application of lime is to reduce such toxic effects. However, soil acidity becomes self adjusting at 6.2 or 6.3 when all four cations - calcium, magnesium, potassium and sodium - are in proper equilibrium (Kinsey and Walters, 2006). Anyone of them in excess can push pH up, and anyone of them in lower amounts can lower pH. CA systems are based on building and breaking down organic matter to maintain soil health and productivity. As microorganisms decompose soil organic matter, organic acids are continuously being formed. If these acids are not neutralized by free bases, then soil acidity will increase. There are other reasons why soil can be acidic, due to leaching of basic cations by rainfall, or to soil being formed from acid parent materials, or to biological nitrogen fixation. Where soils are acidic particularly in humid and subhumid soils and may have toxic levels of aluminum, the effectiveness of broadcast lime application without incorporation has been long proven in CA systems, as lime moves into deeper soil layers, especially when applied in small quantities each year in combination with green manure cover crops (Derpsch, 2007b). Increasing Diversity of Cropping and Integrating Livestock The benefits of crop rotation in controlling pests and disease build-up are well-established and not unique to CA. In particular, rotations with grain legumes offer the additional benefits of enhancing soil fertility through biological N2-fixation. Yet rotations with legumes or other crops are frequently less economically attractive and leave less soil cover. Even where the profitability of cereal production is limited, smallholder farmers often grow crops such as maize in continuous monoculture for food security reasons and their limited labor requirements (Baudron et al., 2012a). Diverse multiple crop/pasture systems are required rather than crop rotations alone. Intercropping is particularly important on small farms in the tropics. A major benefit of multiple cropping is weed, pest and disease management. Legume cover crops and short-duration fallows of fast-growing legume trees can fix substantial amounts of N2 from the air and improve soil fertility giving strong increases in the yield of subsequent cereal crops as well as providing substantial biomass for mulch (Naudin et al., 2012). Despite many claims of adoption of green manures or cover crops by smallholder farmers, these have not outlived the promotion campaigns due to the substantial investment of land and labor required and the delayed benefits to farmers.
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Soil Erosion Control A major benefit of CA is the control of soil erosion due to maintenance of soil cover, greater infiltration and reduced runoff (Erenstein, 2002). However, when no-till is practiced in the absence of effective soil mulch cover, the effects can be disastrous with rapid surface sealing leading to increased run-off and accelerated soil erosion (Guto et al., 2011). Rather than focusing on “no-till or minimal soil disturbance,” tillage, and soil conservation measures should be used strategically. Prevention of soil erosion requires a more integrated approach to soil conservation than simply no/reduced tillage and mulch. Where no-tillage is adopted, often it is practiced as non-permanent rotational tillage and the average time out of tillage is approximately 2 years (Derpsch et al., 2010). Tillage can be important in loosening the soil and creating a rough soil surface to enhance water infiltration where mulch is not available. Towards CA-Based Nutrient Management Practices Integrated Soil Fertility Management (ISFM) and Integrated Natural Resources Management (INRM) approaches of various types and nomenclature have been in vogue in recent years in certain sections of the scientific community. Generally, such approaches are focused more on meeting crop nutrient needs rather than managing soil health and land productivity as is the case with CA systems. Also, most of the work that is couched under the rubric of ISFM or INRM Over the past 15 years or so has been geared towards tillage-based systems which have many unsustainable elements, regardless of farm size or the level of agricultural development. Unless the concepts of soil health and function are explicitly incorporated into ISFM or lNRM approaches, sustainability goals and means will remain only accidentally connected, and sustainable crop intensification will be difficult to achieve particularly by resource poor farmers. We believe that CA systems have within them their own particular sets of ISFM or INRM processes and concepts that combine and optimize the use of organic with inorganic inputs integrating temporal and spatial dimensions with soil, nutrient, water, soil biota, biomass dimension, all geared to enhancing crop and system outputs and productivities but in environmentally responsible manner. There is empirical evidence to show that CA-based ISFM or lNRM processes can work because of the underpinnings of soil health and function. Focusing on soil fertility but without defining the tillage and cropping system, as often proposed by ISFM or INRM approaches, is only a partial Page | 25
answer to enhancing and maintaining soil health and productivity in support of sustainable production intensification, livelihood and the environment. Over the past two decades or so, empirical evidence from the field has clearly shown that healthy agricultural soils constitute biologically active soil systems within landscapes in which both the soil resources and the landscape must operate with plants in an integrated manner to support the various desired goods and services (e.g., food, feed, feedstock, biological raw material for industry, livelihood, environmental services, etc) provided by agricultural land use. Consequently, successful nutrient management strategies as part of any ISFM or INRM approach must pay close attention to issues of soil health management which means managing the microscopic integrity of the soil~ plant system particularly as mediated by soil living biota, soil organic matter, soil physico-chemical properties, available soil nutrients, adapted germ plasma as well as to managing the macroscopic dimensions of landscapes, socioeconomics and policy. Given that CA principles and practices offer substantial benefits to all types of farmers in most agro-ecological and socioeconomic situations, CA-based IFSM and INRM approaches to nutrient management and production intensification would be more effective for farmer-based innovation systems and learning processes such as those promoted through Farmer Field School] networks. Adopting a CA-Based Nutrient Management Framework CA has now emerged as a major "breakthrough" systems approach to crop and agriculture production with its change in paradigm that challenges the status quo. However, as a multi-principled concept, CA translates into knowledge-intensive practices whose exact form and adoption requires that farmers become intellectually engaged in the testing, learning and fine tuning possible practices to meet their specific ecological and socioeconomic conditions (Friedrich and Kassam, 2009). In essence, CA approach represents a highly biologically and biogeophysically-integrated system of soil health and nutrient management for production that generates a high level of "internal" ecosystem services which reduces the levels of "external" subsidies and inputs needed. CA provides the means to work with natural ecological processes to harness greater biological productivities by combining the potentials of the endogenous biological processes with those of exogenous inputs. The evidence for the universal applicability of CA ·principles is now available across a range of ecologies and socio-economic situations covering large and Page | 26
small farm sizes worldwide, including resource poor farmers (Goddard et al., 2007). There are' many different ecological and socio-economic starting situation~ in which CA has been and is being introduced. They all impose their particular constraints as to how fast the transformation towards CA systems can occur. In the seasonally dry tropical and sub-tropical ecologies particularly with resource poor small farmer in drought prone zones, CA systems will take longer to establish, and step-wise approaches to the introduction of CA practices seem to show promise (Mazvimavi and Twomlow, 2006). These involve two components: the application of planting 'Zai-type' basins which concentrate limited nutrients and water resources to the plant, and the precision application of small or micro doses of nitrogen-based fertilizer. In the case of degraded land in wet or dry ecologies, special soil amendments and nutrient management practices are required to establish the initial conditions for soil health improvement and efficient nutrient management for agricultural production (Landers, 2007). What seems to be important is that whichever pathway is followed to introduce CA practices, there is a need for a clear understanding of how the production systems concerned should operate as CA systems to sustain soil health and productivity, and how nutrient management interventions that may be proposed can contribute to the system effectiveness as a whole both in the short- and long-term. Benefits and Problems Associated with Tillage One agricultural practice that has been adopted by farmers since the move from hunters and gatherers to more settled food production systems ten thousand years ago is tillage. Tillage is the act of disturbing the soil through use of an implement powered manually or by animals or tractors. Other names for tillage include plowing, cultivation, digging, etc. There are many reasons for adopting tillage with some of the main reasons listed below:
It is used to incorporate the previous crop residues, weeds, or amendments added to the soil, such as inorganic or organic fertilizers.
It is the first step in the preparation of a seedbed, essentially the name for soil that is prepared to receive the seed of the planted crop. For most seeding systems, manual or tractor powered, some soil loosening and residue management is needed to allow the seed to be placed at a proper depth for germination in the soil. Page | 27
It helps aerate the soil organic matter, which in turn helps release and make available to plants nutrients tied up in this important soil component.
It is a recommended practice for controlling several soil and residue borne diseases and pests, since residue burial and soil disturbance have been shown to help alleviate this problem.
It provides compaction relief, maybe only temporarily, a physical property of soil that restricts root and water penetration and reduces production.
Lastly, tillage is aesthetically pleasing in terms of look and smell.
Tillage Also has Detrimental Effects on Both the Environment and Farmers Tillage costs money in the form of fuel for tractors, wear and tear on equipment, and the cost of the operator. If animals are used as the power source, the costs of feeding and caring for the animals over a full year are also high.
Greenhouse gas emissions from the burning of the diesel fuel add to global warming.
Soil organic matter is oxidized when it is exposed to the air by tillage with resulting declines, unless organic matter is returned to the soil as residues, compost, or other means.
Tillage disrupts the pores left by roots and microbial activity. What is less known is what effect this has on below ground soil biology?
The bare surface exposed after tillage is prone to breakdown of soil aggregates as the energy from raindrops is dissipated. This results in clogging of soil pores, reduced infiltration of water and runoff, which leads to soil erosion. When the surface dries, it crusts and forms a barrier to plant emergence.
The bare surface after tillage is prone to wind erosion
The tractor wheels compact the soil below the surface.
For the several decade farmers have been adopting conservation tillage practices that reduce tillage and maintain a residue cover on the soil. This is called conservation tillage (CT) and is defined as follows: “Conservation tillage is the collective umbrella term commonly given to no-tillage, direct-drilling, minimum-tillage and/or ridge-tillage, to denote that the specific practice has a conservation goal of some nature. Usually, Page | 28
the retention of 30% surface cover by residues characterizes the lower limit of classification for conservation-tillage, but other conservation objectives for the practice include conservation of time, fuel, earthworms, soil water, soil structure and nutrients. Thus residue levels alone do not adequately describe all conservation tillage practices.” (Baker et al. 2002) This has led to confusion among the agricultural scientists and, more importantly, the farming community. To add to the confusion, the term conservation agriculture has recently been introduced by the FAO (Food and Agriculture Organization website) and others and its goals defined by FAO as follows: “Conservation agriculture (CA) aims to conserve, improve and make more efficient use of natural resources through integrated management of available soil, water and biological resources combined with external inputs. It contributes to environmental conservation as well as to enhanced and sustained agricultural production. It can also be referred to as resource efficient or resource effective agriculture.” (FAO) This encompasses the sustainable agricultural production need that all humankind obviously wishes to achieve. But this term is often not distinguished from conservation tillage. FAO mentions in its CA website that “Conservation tillage is a set of practices that leave crop residues on the surface which increases water infiltration and reduces erosion. It is a practice used in conventional agriculture to reduce the effects of tillage on soil erosion. However, it still depends on tillage as the structure forming element in the soil. Nevertheless, conservation tillage practices such as zero tillage practices can be transition steps towards Conservation Agriculture.” In other words conservation tillage uses some of the principles of conservation agriculture, but has more soil disturbance. FAO has characterized conservation agriculture as follows: “Conservation Agriculture maintains a permanent or semi-permanent organic soil cover. This can be a growing crop or dead mulch. Its function is to protect the soil physically from sun, rain and wind and to feed soil biota. The soil micro-organisms and soil fauna take over the tillage function and soil nutrient balancing. Mechanical tillage disturbs this process. Therefore, zero or minimum tillage and direct seeding are important elements of CA. A varied crop rotation is also important to avoid disease and pest problems.” (FAO website) Conservation agriculture does not just mean not tilling the soil and then Page | 29
doing everything else the same. It is a holistic system with interactions among households, crops, and livestock since rotations and residues have many uses within households; the result is a sustainable agriculture system that meets the needs of farmers. CA is Based on Three Principles: (1) Minimal soil disturbance or notill; (2) Continuous soil cover-with crops, cover crops or a mulch of crop residues; (3) Crop rotation (FAO, 2015). The first two principles are interdependent-mulch cannot be maintained when the soil is tilled. “True” CA is deemed to be practiced only when all three principles are meticulously applied (Derpsch et al., 2014). Characteristic Features Between Conventional and CA In the conventional agriculture, management practices are extensively used of various tillage operations for plowing of the land for preparation of seedbed and to keep weed down, i.e., moldboard or animal drawn plow or harrowing, drilling, cultivator, etc. These tillage operations are repeated many times; due to this conditions break down the soil structure and destroy pore and soil becomes prone to erosion and leads to heavy cost of time, fuel, and labor. However, conventional tillage exposed soil to air and sunlight which causes oxidation of organic matter and leads to low carbon content in soil which affects soil structure. The oxidation of organic matter releases CO2 into environment which causes global warming or climate change. The conservation agriculture system involves specific agronomic field operations such as minimum soil disturbance or use of zero tillage or NT, soil cover with green manure or crop residue (mulching), and crop rotation; these management practices are highly beneficial for farm community because it saves fuel, time, and labor as well as it provides good soil structure, porosity, more accumulation of the organic matter in soil which provides better soil aggregation, water-holding capacity, soil moisture for the long term, nutrient recycling, and transformation. Meanwhile, the conservation tillage improves soil fertility, water, and crop productivity; the no-tillage gives better soil protection than conventional tillage. This happens as the conventional tillage system leaves ~1–5% of the soil surface covered with crop residues. Conventional Agriculture
Conservation Agriculture
Cultivation of land with the help of Minimal disturbances to nature during machinery, using science and technology crop grown processes Excessive motorized tillage and leads to No-tillage or considerably reduced deterioration of soil pores or structure tillage (bio-tillage) increases porosity
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Higher wind speed and water erosion
Lower wind speed and water erosion
Removal of crop residue from field or burning or uncovered surface
Soil covered with crop residue permanently covered
Low water infiltration
High rate of infiltration of water
Decrease water –holding capacity
Enhance water-holding capacity
FYM/composts added from outside or green manuring (incorporated)
Use of in situ organics/composts or brown manuring/cover crops (stubble retention)
Due plowing established weeds are kills Weeds create problem during early but also stimulates more weed seeds to stage of implementation but reduce germinate with time Soil become very compacted due to more Control of traffic, there is less use of heavy traffic or machinery compaction
Benefits of Conservation Agriculture The benefits will be looked at in relation to minimal soil disturbance, permanent ground cover, and rotation since they all interact to provide the benefits, which include the following: a.
Yields in the rice-wheat (RW) systems of the Indo-Gangetic Plains in South Asia are higher with no-till because of timelier planting and better stands.
b.
One of the major benefits of CA, which makes it popular with farmers, is it costs less in terms of money but also time mostly due to using less diesel fuel, less labour, and less pumping of water. Since planting can be accomplished in one pass of the seed drill, time for planting was also reduced, thus freeing farmers to do other productive work.
c.
Water-use efficiency increased in the RW system because often the first irrigation could be dispensed with, and when the first irrigation was given the water flowed faster across the field. Water savings of 15-50% have been calculated with the greater savings occurring when crops are planted on beds. Other systems using no-till and permanent ground cover show reduced water runoff, better water infiltration and more water in the soil profile throughout the growing period.
d.
The mulch helps promote more stable soil aggregates as a result of increased microbial activity and better protection of the soil surface.
e.
CA resulted in improved fertilizer efficiency (10-15%) in the ricewheat system, mainly a result of better placement of fertilizer with the seed drill as opposed to broadcasting with the traditional system Page | 31
(Hobbs and Gupta 2004). In some report nitrogen fertilizer efficiency was recorded as lower, a result of micro-organisms tying up the nitrogen in the residue. However, in other longer-term experiments, release of nutrients increased with time because of more active microbial activity and nutrient recycling. f.
No-till uses less diesel fuel and thus results in lower carbon dioxide emissions, one of the gases responsible for global warming. In RW systems, 40-60 litres of diesel fuel are saved because farmers can forego the practice of plowing many times to get a good seedbed after harvesting rice planted after puddled rice in degraded soils (Hobbs and Gupta 2004).
g.
Weeds have been shown to germinate less in CA in RW systems (50-60% less because the soil is less disturbed and less grassy weeds (Phalaris minor) germinate than in tilled soils. There is also evidence of allelopathic properties of cereal residues in respect to inhibiting surface weed seed germination (Jung et al. 2004). Weeds will also be controlled when the cover crop is cut, rolled flat, or killed by herbicides. Farming practices that maintain soil microorganisms and microbial activity can also lead to weed suppression by biological agents (Kennedy 1999).
h.
CA results in more biotic diversity in the soil as a result of the mulch and less disturbance. This also produces higher surface are tilled. Note the surface mulch also helps moderate soil temperatures and moisture, which is more favorable for microbial activity.
i.
Interaction between root systems and rhizobacteria effect crop health, yield and soil quality. Release of exudates by plants activate and sustain specific rhizobacterial communities that enhance nutrient cycling, nitrogen fixing bio-control of plant pathogens, plant disease resistance, and plant growth stimulation. Groundcover would be expected to increase biological diversity and increase these beneficial effects.
Essentially CA takes advantage of biological processes in the soil to accomplish biological tillage; this improves networks of interconnected pores, nutrient recycle and soil physical and biological health. Life in the soil is a highly complex and dynamic system that is sensitive to tillage, pesticides, and other toxins. Increase in nutrient availability and plant productivity depends on regaining a healthy soil food web. Following are some key considerations for healthy soils:
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Soil organic matter formation and the multitude of organisms involved fauna and flora;
Healthy roots and the synergistic associations with biological organisms e.g. rhizobia, mycorrhiza, antifungal agents, etc.;
Soil microbes protect their territory and through a balance that stabilizes the population;
Some microbes help roots control disease antifungal agents;
Healthy soils have more microbes than unhealthy soils;
Mulching helps promote more diversity of microbes thro moisture moderation; and
It is hypothesized that CA plays a critical role in underground diversity and disease and pest suppression.
Important Barriers for the Adoption of Conservation Agriculture The CAPs are facing a great challenge between the scientific community and the farmers to change the mind-set and explore the opportunities that offer for natural resource management. The CA is also considered as way to sustainable agriculture (Sangar et al. 2005). A mental change of farmers, technicians, extensionists, and researchers away from conventional method which is soil degrading tillage toward natural resource-conserving systems like no-tillage is the need of the hour (Derpsch 2001). Hobbs and Govaerts (2010), however, reported that probably the most important factor in the adoption of CA is change of mental attitude of farmer to tillage. The following are a few important constraints which restrict wide-scale adoption of CA:
Lack of Appropriate Machinery Especially For Small And Medium Farmers: Although significant efforts have been made in developing and promoting machinery for seeding wheat in notillage systems, successful adoption will require rapid effort in developing, standardizing, and promoting quality implements aimed over a range of crops and cropping sequences (Bhan and Behera 2014).
The Great Use of Crop Residues for Animal Feed and Fuel: Especially under rain-fed or dry land situations, farmers face a scarcity of fodder due to less biomass production of different crops. There is competition between CAPs and animal feeding for crop residue. This is a major problem for adoption of CA (Bhan and Behera 2014). Page | 33
Burning of Crop Residues: For timely sowing of the next crop and without machinery for sowing under CA systems, farmers prefer to sow the crop in time by burning the residue. This has become a common feature in the rice-wheat system in north India. This creates environmental problems for the region (Tripathi et al. 2013).
Lack of Knowledge About The Potential of Ca to Agriculture Leaders, Extension Agents, and Farmers: This implies that the whole range of practices in CA, including planting and harvesting, water and nutrient management, diseases and pest control, etc., need to be evolved, evaluated, and matched in the context of new systems (Bhan and Behera 2014).
Skilled and Scientific Manpower: Managing CA systems, need for enhanced capacity of researchers to face problems from a systems perspective and to be able to work in close relationship with farmers and other stakeholders. Strengthened knowledge and information sharing mechanisms are urgently needed.
Some area-specific constraints in semiarid areas during the transformation to CA system relate to initial low supply of crop residues and vegetation biomass for soil mulch cover development, to initial short-term competition for crop residue as animal feed, and to weeding during initial phase while soil mulch cover and integrated weed management practice is being established. However, farmers, those are really interested in adoption of CA, are finding solution for these problems locally. Lots of this type of cases has been reported for small and large farms in different parts of the world. It is said that convincing farmers that crop cultivation is also possible with reduced tillage is major problem in promotion and adoption of CA system on a wide scale. Policy Issues Required for CA The CA implies a radical transformation from traditional agriculture. There is need of policy intervention to integrate with existing technologies and how policy issues promote or deter CA. Some of the important policies needed for promotion of CA are given below.
Scaling up CA Practices: More and more support from stakeholders including policy and decision makers at the local, regional, and national levels will facilitate promotion of CA and help farmers to earn more profit. In couple of the last decade, much research work has been done on CA especially in India. However, Page | 34
its expansion to end user is very limited. One of the possible reasons for limited adoption of the technology by the farmers was mind-set of a large group of farmers about tillage (Hobbs and Govaerts 2010). Under such situations, during initial phase farmer’s participatory on-farm research to test the technology followed by wide-scale demonstration in subsequent years is required. In India, efforts are being started through a network research project for onfarm evaluation and demonstration of CA technology for its expansion (Bhan and Behera 2014).
The Shift in Focus from Food Security to Livelihood Security: Myopic “food security” policy based on cereal production must now replace a well-articulated policy goal for livelihood security. This will help the horizontal or vertical diversification of major cropping systems in the IGPs, as continuous use of rice–wheat cropping system has overexploited the natural base by the use of conventional tillage practices. Policy intervention also affects cropping pattern and crop diversification of the region. The policies that affect crop horizontal and vertical diversification are pricing policy, tax and tariff policies, trade policies, and policies on public expenditure and agrarian reforms (Behera et al. 2007).
Developing, improving, standardizing machinery for sowing, fertilizer application, and harvesting that require least soil disturbance in crop residue management under different soil conditions will be key to success of CA. In hilly areas, small landholders’ bullock-drawn equipment will have highly importance. In these situations, the subsidy support from national or local government bodies for manufacturing low-cost implements will help in the expansion of CA practices.
There is a Need to Develop and Evaluate Crop Varieties Suitable to CA Technologies: Farmer’s participatory research would appear promising for identifying and developing crop cultivars performing well to a particular region.
Training on CA Are Also Required for Capacity Building through Policy Intervention: Lack of trained technical person at field level is major drawback in adoption and expansion of CA. Efforts to perfectly train all agricultural extension personnel on CA should be made in relevant departments.
Support for The Adaptation and Validation of Ca Technologies Page | 35
in Local Environments: To promote principles and practices of CA at local conditions, adaptive research is the need of the hour. This should be done in partnership with local people and other stakeholders. The resource-poor and smallholder farmers in India do not have economic access to new seeds, herbicides and seeding machineries etc., this calls for policy frame work to make easily available critical inputs (Sharma et al. 2012).
Support the Manufacturing of Ca Machinery and Ensure its Availability: equipments required in CA practices are very complex as well as expensive for a farmer to purchase it. Therefore, a farmer may develop a local hire service industry by providing equipment to hire on custom basis. The new machineries, viz., happy seeder, turbo seeder, laser land leveler, etc., are found useful for CA practices, but these machines are not suitable for small and marginal farmers groups. These machines need high horse power (>50 hp) tractors for better functioning in field conditions. Small and marginal farmers having small holdings and economic limitations are unable to afford for such heavy machines. They need policy interventions for manufacturing of smaller versions of these machines at the local level (Bhan and Behera 2014).
Promote Payments for Environmental Services (Pes) and Fines for Faulty Practices: by the adoption of CA practices, farmers improve the quality of environment by storing carbon in soil, reducing runoff and soil erosion by mulching and promotion of groundwater recharge. It provides eco-friendly services, so farmers should be rewarded for such services, which improves quality life of all living beings on the planet.
Crop production in the next decade will have to produce more food from less land by making more efficient use of natural resources—and with minimal impact on the environment. Only by doing so can food productions keep pace with demand, while land’s productivity is preserved for future generations. Crop and soil management systems that improve soil health parameters (physical, biological, and chemical) and reduce farmer costs are essential. The age-old practice of turning the soil before planting a new crop is a leading cause of farmland degradation. Tillage is a root cause of agricultural land degradation - one of the most serious environmental problems worlds wide – which poses a threat to food production and rural livelihoods. Combined with the lack of importance accorded to the role of soil microorganisms and soil biological processes in mainstream production Page | 36
system paradigm during the past century, globally we currently have most of our agricultural lands performing under suboptimal and degrading conditions. As long as and where ever the tillage-based paradigm continues to hold sway, it will also inhibit the development of agricultural production systems and associated policy instruments that can enhance environmental services from agricultural land use, address global challenges of climate change, and cope with the rise in food, energy and production costs. References 1.
Baker CJ, Saxton KE, Ritchie WR. No-tillage seeding: Science and practice. 2nd Edition. Oxford, UK: CAB International.
2.
Baudron F, Andersson JA, Corbeels M, Giller KE. Failing to Yield? Ploughs, conservation agriculture and the problem of agricultural intensification: an example from the Zambezi Valley, Zimbabwe. J Dev. Stud. 2012a; 48:393-412.
3.
Behera UK, Sharma AR, Mahapatra IC. Crop diversification for efficient resource management in India: problems, prospects and policy. J Sustain Agric. 2007; 30(3):97-217.
4.
Bhan S, Behera UK. Conservation agriculture in India-problems, prospects and policy issues. Int Soil Water Conserv Res. 2014; 2(4):112.
5.
Boddey RM, Bruno JR A, Segundp U. Leguminous biological nitrogen fixation in sustainable tropical agro-ecosystems. (In): Biological approaches to sustainable soil systems. Uphoff, N. et al. (Eds). CRC Press, Taylor & Francis Group, 2006, 401-408.
6.
Derpsch R. Keynote: frontiers in conservation tillage and advances in conservation practice. In: Stott DE, Mohtar RH, Steinhart GC (eds) Sustaining the global farm. Selected papers from the 10th International Soil Conservation Organization Meeting held May at Purdue University and the USSA-ARS National Soil Erosion Research Laboratory, 1999, 2001, 24-29.
7.
Derpsch R. Critical steps in no-till adoption. (In): No till farming systems. Goddard T. et al. (Eds). WASWC Special Publication No. 3, Bangkok, 2007b, 479-495.
8.
Derpsch R, Friedrich T, Kassam A, Li H. Current status of adoption of no-till farming in the world and some of its main benefits. Int. J Agric. Biol. Eng. 2010; 3:1-25. Page | 37
9.
Derpsch R, Franzluebbers AJ, Duiker SW, Reicosky DC, Koeller K, Friedrich T et al. Why do we need to standardize no-tillage research? Soil Till. Res. 2014; 137:16-22.
10. Erenstein O. Crop residue mulching in tropical and semi-tropical countries: an evaluation of residue availability and other technological implications. Soil Till. Res. 2002; 67:115-133. 11. Erenstein O, Gérard B, Tittonell P. Biomass use trade-offs in cereal cropping systems in the developing world: overview. Agric. Syst. 2015; 134:1-5. 12. FAO, Food and Agriculture Organization of the United Nations, conservation agriculture, 2015. 13. Friedrich T, Kassam AH. Adoption of conservation agriculture technologies: constraints and opportunities. Invited paper, IV World Congress on Conservation Agriculture, 4-7 February. New Delhi, India, 2009. 14. Goddard T, Zoebisch M, Gan Y, Ellis W, Watson A, Sombatpanit S. (Eds). No-till Farming System. WASWC Special Publication No.3, Bangkok, 2007, 544. 15. Guto S, Pypers P, Vanlauwe B, de Ridder N. Tillage and vegetative barrier effects on soil conservation and short-term economic benefits in the Central Kenya highlands. Field Crop Res. 2011; 122:85-94. 16. Hobbs PR, Govaerts B. How conservation agriculture can contribute to buffering climate change. In: Reynolds MP (ed) Climate change and crop production. CAB International, Cambridge, 2010, 177-199. 17. Hobbs PR, Gupta RK. Problems and challenges of no-till farming for the rice-wheat systems of the Indo-Gangetic Plains in South Asia. In R. Lal, P. Hobbs, N. Uphoff, and D.O. Hansen (eds.), Sustainable Agriculture and the Rice-Wheat System. Columbus, Ohio, and New York, USA: Ohio State University and Marcel Dekker, Inc, 2004, 10119. 18. Kennedy AC. Soil microorganisms for weed management. J Crop Prod. 1999; 2:123-38. 19. Kinsey N, Walters C. Neal Kinsey's hands-on agronomy: understanding soil fertility & ferlilizer use. Acres USA, 2006, 391. 20. Landers J. Tropical crop-livestock systems in conservation agriculture: The Brazilian Experience. Integrated Crop Management 5. FAO, Rome, 2007. Page | 38
21. Mazvimavi K, Twomlow S. Conservation farming for agricultural relief and development in Zimbabwe. (In): No-till Farming Systems. Goddard T. et al. (Eds). W ASWC Special Publication No. 3, Bangkok, 2006, 169-175. 22. Naudin K, Bruelle G, Salgado P, Penot E, Scopel E, Lubbers M et al. Trade-offs around the use of biomass for livestock feed and soil cover in dairy farms in the Alaotra lake region of Madagascar. Agric. Syst. 2014; 134:36-47. 23. Sangar S, Abrol JP, Gupta RK. Conservation agriculture: conserving resources enhancing productivity. CASA, NASC Complex, New Delhi, 2005, 19. 24. Seguy L, Bouzinac S, Husson O. Direct-seeded tropical soil systems with permanent soil Cover: learning from Brazilian experience. (In): Biological Approaches to Sustainable Soil Systems. Uphoff, N. et al. (Eds). CRC Press, Taylor & Francis Group, 2006, 323-342. 25. Sharma AR, Jat ML, Saharawat YS, Singh VP, Singh R. Conservation agriculture for improving productivity and resource-use efficiency: prospects and research needs in Indian context. Indian J Agron 57(IAC Special Issue), 2012, 131-140. 26. Shaxson F, Kassam AH, Friedrich T, Boddey B, Adekunle A. Underpinning conservation agriculture's benefits: The roots of soil health and function. Main background document for the Workshop on Investing in Sustainable Crop Intensification: the Case for Improving Soil Health, July, FAO, Rome, 2008, 22-24. 27. Tripathi S, Singh RN, Sharma S. Emissions from crop/biomass residue burning risk to atmospheric quality. Int Res J Earth Sci. 2013; 1(1):2430.
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Chapter - 3 Anatomical, Physiological and Hormonal Aspects of Abscission in Fruit Crops
Authors Kaluram Ph.D Scholar, Division of Fruit Crops, ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka, India Tanushree Sahoo Ph.D Scholar, Division of Fruits and Horticultural Technology, ICAR-Indian Agricultural Research Institute, New Delhi, India Swosti Debapriya Behera Ph.D Scholar, Department of Horticulture, Assam Agricultural University, Jorhat, Assam, India
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Chapter - 3 Anatomical, Physiological and Hormonal Aspects of Abscission in Fruit Crops Kaluram, Tanushree Sahoo, and Swosti Debapriya Behera
Abstract Abscission enables both vegetative and reproductive organs to be shed in response to developmental, hormonal and environmental cues (Leslie et al., 2007). From an evolutionary point of view, abscission in fruit crops is a highly fruitful event. However, in an agricultural context, abscission is considered as a limiting factor for crop productivity. The phenomenon of abscission mainly occurs at a narrow constriction of tissue called abscission zone; which has small, isodiametric cells with dense cytoplasm (Addicott, 1982). Separation of abscission zone cells involves dissolution of middle lamella with wall-degrading enzymes (Roberts et al., 2002). IAA retards, whilst ethylene is a potent accelerator of the process. However, abscission serves as function in removing plant parts containing waste materials, nutrient diversion and dissemination of fruits and seeds. Therefore, it depends on precise regulation of the abscission process in plant system as per the situation specific need, which can certainly improve the crop productivity and quality. Keywords: abscission, IAA, ethylene, middle lamella Introduction The process of abscission is an important developmental event in the life cycle of a plant. Shedding of organs including leaves, fruit and flowers is a highly co-ordinated event involving multiple changes in cell structure, metabolism and gene expression. The last 10 years have seen a rapid expansion of our knowledge and understanding of the process at all levels. Although commercially important, the process seems to have been used as a tool for understanding the physiology of hormone action for many years, rather than as an important developmental event in its own right. The word ‘Abscission’ owes its origin from a Latin word ‘Ab’ meaning away & ‘Scindere’ meaning to cut. Abscission enables both vegetative (buds and Page | 43
leaves) and reproductive (flower parts, entire flowers, ovaries, mature seeds, and developing and ripening fruits) organs to be shed in response to developmental, hormonal and environmental cues (Addicott, 1982; Leslie et al., 2007). Why Abscission is Required? 1) An organ might be shed once it is no longer needed. 2) For recycling substances for generation of energy. 3) In order to adapt in the changing environment (Taylor and Whitelaw, 2001). 4) In order to prevent spreading of diseases (Roberts et al., 2002). 5) To enhance reproductive success. 6) To avoid competition for resources. Types of Abscission 1.
Normal Abscission: Caused by senescence or ripening.
2.
Abnormal Abscission: Caused by stresses, higher or lower temperature, drought or flood, insects or diseases.
3.
Physiological Abscission: Caused by disorders in physiology itself, such as nutritional competition between vegetation and regeneration, sink and source.
Steps of Abscission STEP I- Differentiation of AZ tissue. STEP II- Acquisition of competence to signals. STEP III- Execution. STEP IV- Formation of protective layer.
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Anatomical Aspects Abscission Zone
A narrow constriction in tissue composed of small, isodiametric cells with dense cytoplasm (Addicott, 1982).
Separation of abscission zone cells involves dissolution of middle lamella with wall-degrading enzymes (Roberts et al., 2002).
The cells that comprise the separation zone are often morphologically distinguishable before the onset of abscission.
They appear to have lost the capacity to enlarge and to become vacuolated as part of the normal growth process, although they do enlarge during abscission.
There are five different abscission zones are defined in case of citrus i.e., between petiole & the branch, between petiole & leaf blade, branch & fruit peduncle, in the calyx and between the style & ovary.
Apparently, most cells in the AZ are parenchymatous with tracheid elements, with thin walls that contain a small amount, or none, of lignin and suberin.
Prior to onset of abscission process, suberin & lignin increases in these cells and starch grains accumulate (Scott et al., 1948). Scott et al., 1948 reported that, during abscission, volume of cells proximal to the AZ increase with no meristematic activity.
Only cell elongation without cell division was reported.
Abscission was accompanied by wall thickening in AZ cells and by gelatinization of cell wall (Hodgson, 1918).
According to Chaudhri (1957), the first stage of abscission in the LAAZ was thickening of the middle lamella, followed by degradation of the primary wall.
The cells that comprise a separation layer have been termed abscission zone target cells (Osborne, 1976). These cells that enlarge in response to ethylene but not to auxin have been classified as Type 2 target cells.
Type I expand longitudinally in response to auxin but not ethylene, but may expand laterally to ethylene application, for example in pea epicotyls; Type 3 cells expand in response to both hormones (Osborne, 1976). In Page | 45
Type 2 cells the opposing effects of these two hormones provide a regulatory mechanism for the control of cell size and shape by the balance of auxin and ethylene.
The responses of the separation zone cells were an expression of a precise positional differentiation. In a subsequent paper Osborne & Sargent (1976b) were able to show that until these target cells were present, abscission could not be induced even by prolonged exposure to high concentrations of applied ethylene.
Abscission zones can be considered to be multicellular structures in which cell to cell separation occurs between a subset of cells within the zone.
The number of cells that actually undergo separation has several implications in terms of the signalling events associated with the abscission process; do all cells within the layer respond individually, or is there intercellular communication within the layer so that only a relatively small proportion of the cells have to be able to recognize and initially respond to the primary abscission signal.
(A) Detail of a leafy inflorescence of clementine showing the pedicel AZ (AZ-A) located within the pedicel. (B) Light micrograph of a longitudinal section through a clementine flower pedicel showing AZ-A. [Estornell et al., 2012].
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(C) A longitudinal section through the calyx region of a mature fruit of ‘Washington navel’ orange (Citrus sinensis) showing the calyx AZ (AZ-C) [Estornell et al., 2012]. Physiological & Hormonal Aspects
Theories Behind the Mechanism
The Turgor Theory: Proposed that the solute concentration in the separation zone cells increased as a result of starch degradation. The increased turgor pressure generated in the cells caused them to round up, tearing the wall along the line of middle lamella (Sextone, 2005).
Second theory believes that, abscission involves the induction of wall degrading enzymes. It has also been shown that, protein synthesis inhibitors will stop rapid abscission of petals, removing one of the last objections to the involvement of wall hydrolases.
Different Factors Responsible for Abscission
Chemical- Reactive Oxygen Species (ROS) during stress disrupts homeostasis of cellular components and expresses cell WDEs.
Enzymes like ß-1, 4-endo-glucanase (EGase), Polygalacturonase (PG), Cellulase, Pectinase, Catalase.
Others like Arabinogalactan-proteins (AGPs), Expansin etc.
Genetic- several genes have been shown to play important roles in the establishment of specific sites of AZ.
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Environmental and Developmental Signals 1.
Senescence: Abscission is frequently associated with senescence as both processes are initiated by many of the same developmental as well as environmental and stress factors
2.
Photoperiod: Dark and low-light treatments have been shown to increase abscission of flowers, flower buds, leaves and fruits
3.
Water Stress: Drought conditions and other stresses that cause a deficiency in water, including salt, cold and high temperatures, can also promote abscission as a result of a decline in the growth and vigour of the plant.
4.
Wounding & Pathogen Attack: Wounding caused by herbivore feeding or other mechanical damage can provide possible entry points for pathogens, which is why the plant responds by inducing a defense response involving substantial alteration in gene expression.
5.
Ozone: PR proteins such as b-1, 3-glucanase and chitinase are preferentially induced after ozone treatment (Schaudner et al., 1996). Also, in response to ozone, the leaves of potato plants sequentially express two ACC synthase genes.
Physiological Changes during Abscission
One of the first detectable changes during the lag phase is the accumulation of cytoplasm and organelles in the abscission zone cells. Page | 48
It is associated with the change in the rate of respiration and incorporation of precursors in to both RNA and proteins.
The activation of leaf abscission zone cells in plants were associated with an increase in soluble proteins.
Abeles et al. (1979) reported a concurrent increase in RNA and protein synthesis with ethylene application.
An increase in endo-cellulase and exo-polygalacturonase activities were found with ethylene application.
A similar increase in the activities of these enzymes in abscission zone cells with ethephon treatment has been reported by Rascio et al. (1985) in peach.
Atkinson et al. (2002) showed that PG over-expression in transgenic apple lead to premature leaf shedding in some phenotypes due to reduced cell adhesion in leaf abscission zones.
The increased activities of hydrolytic enzymes are responsible in cell wall degradation (Ward et al., 1999).
Ethylene application also increased peroxidase activity in leaf abscission zone. Poovaiah et al. (1973) reported 10 to 15 fold increase in peroxidase isoenzymes with induction of abscission.
Inter- and Intracellular Signals Role of Ethylene and Auxin
Ethylene and auxin (IAA) are important regulators of abscission.
IAA retards, whilst ethylene is a potent accelerator of the process.
The general rule portrays that provided the flux of IAA to the abscission zone region is maintained, then cell separation is Page | 49
inhibited and abscission does not occur (Addicott, 1982; Sexton et al., 1985).
The auxin status of the abscission zone controls the sensitivity to ethylene thus any factor that affects the supply of auxin to the zone will also affect the sensitivity to ethylene.
Mechanisms of Plant Hormone Signal Perception
Plant hormones are ideal candidate ligands for such receptor proteins in that binding of the hormone to the receptor allows initiation of signalling events influencing many developmental and physiological processes.
Receptor proteins that bind ethylene have been extensively studied in recent years. The isolation of an Arabidopsis mutant (etr1) that did not show the expected ‘triple’ response to ethylene, that is exaggerated curvature of the apical hook and inhibition of both hypocotyl and root elongation, led to the identification of ETR 1.
One potential target for auxin-regulated degradation are the Aux/IAA proteins.
Roles of Other Hormones and Components of Signal Transduction
Other plant hormones including ABA have a stimulatory effect in some situations (Sexton et al., 1985) but the hypothesis that the stimulatory effect is mediated by production of ethylene remains a matter of debate (Gonzalez-Carranza et al., 1998).
Jasmonates can promote abscission in bean petiole explants without enhancing ethylene production by weakening the mechanical properties of the cell walls in the abscission zone (Miyamoto et al., 1997).
Cytokinins can delay abscission, probably by indirectly delaying senescence.
Cytokinins and gibberellins arriving from the roots also delay senescence and abscission.
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Balance model of plant growth regulators in abscission
Conclusion Abscission is an important process in the life cycle of a plant. Control of abscission in horticultural crops is a key concern. Many genes related to abscission have been identified whose over-expression or down-regulation can help in prevention or promotion of abscission whichever is desirable. However, abscission serves as function in removing plant parts containing waste materials, nutrient diversion and dissemination of fruits and seeds. On the other hand, optimum care must be taken to prevent premature fruitlet abscission, which is the major habbock for reduced productivity in many of the fruit crops. References 1.
Abeles FB, Leather GR, Florrence LE, Craker LE. Abscission: regulation of senescence, protein synthesis and enzyme secretion by ethylene. Hort. Science. 1979; 6:371-376.
2.
Addicott FT, Addicott FT. Abscission. Berkeley, 1982.
3.
Atkinson RG, Schroder R, Hallet IC, Cohen D, MacRae EA. OverPage | 51
expression of polygalacturonase in transgenic apple trees leads to range of novel phenotypes including changes in cell adhesion. Plant Physiol. 2002; 129(1):122-133. 4.
Burns JK. Citrus fruit abscission. Citrus Flowering. Citrus Research and Education Center, Lake Alfred, FL. 33850, USA, 1998, 130-136.
5.
Chaudhri SA. Some anatomical aspects of fruit drop in citrus, 1957.
6.
Estornell LH, Agustí J, Merelo P, Talón M, Tadeo FR. Elucidating mechanisms underlying organ abscission. Plant Science. 2013; 199:4860.
7.
González-Carranza ZH, Lozoya-Gloria E, Roberts JA. Recent developpments in abscission: shedding light on the shedding process. Trends in Plant Science. 1998; 3(1)10-14.
8.
Goren R. Anatomical, physiological, and hormonal aspects of abscission in citrus. Horticultural reviews. 1993; 15:145-182.
9.
Kuhn N, Serrano A, Abello C, Arce A, Espinoza C, Gouthu S, ArceJohnson P. Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission. BMC Plant Biology. 2016; 16(1):234.
10. Leslie ME, Lewis MW, Liljegren SJ. Organ abscission. Annual Plant Reviews. 2007; 25:106-136. 11. Osborne DJ, Morgan PW. Abscission. Critical Reviews in Plant Sciences. 1989; 8(2):103-129. 12. Pandita VK, Jindal KK. October. Physiological and anatomical aspects of abscission and chemical control of flower and fruit drop in apple. In VII International Symposium on Temperate Zone Fruits in the Tropics and Subtropics. 2003; 662:333-339. 13. Pickersgill B. Domestication of plants in the Americas: insights from Mendelian and molecular genetics. Annals of botany. 2007; 100(5):925940. 14. Poovaiah BW, Rasmussen HP, Bukovac MJ. Histochemical location of enzymes in the abscission zones of maturing sour and sweet cherry fruit. J Am. Soc. Hort. Sci. 1973; 98:16-18. 15. Roberts JA, Elliott KA, Gonzalez-Carranza ZH. Abscission, dehiscence, and other cell separation processes. Annual review of plant biology. 2002; 53(1):131-158.
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16. Scott FM, Schroeder MR, Turrell FM. Botan. Gaz. 1948; 109:381-411. 17. Sexton R, Lewis LN, Trewavas AJ, Kelly P. Ethylene and abscission. In: Roberts JA, Tucker GA, eds. Ethylene and plant development. London, UK: Butterworths, 1985, 173-196. 18. Taylor JE, Whitelaw CA. Signals in abscission. New Phytologist. 2001; 151(2):323-340.
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Chapter - 4 Antitranspirant and Super Absorbent: Uses and Response on Plant Life
Authors P.P. Pandey Department of Biological Sciences, Sam Higginbottom University of Agriculture Technology and Sciences, Allahabad, Uttar Pradesh, India M. Suman Department of Biological Sciences, Sam Higginbottom University of Agriculture Technology and Sciences, Allahabad, Uttar Pradesh, India
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Chapter - 4 Antitranspirant and Super Absorbent: Uses and Response on Plant Life P.P. Pandey and M. Suman
Abstract Climate change is affecting weather in many ways. In subtropical region, it is found responsible for drought prone condition as well as temperature rise in coming future. This will drastically bring down the production, if we will not start looking for other possibility to increase WUE (water use efficiency) to cope up with water stress conditions. With the help of antitranspirant and super absorbent there are chances of conserving irrigation water, aiding plant survival under dry conditions, and protecting foliage against fungus, insects, smog, and salt spray. Keywords: WUE (water use efficiency), water stress, antitranspirant, super absorbent. Introduction Water supply and quality will continue to be major global issues as shifts occur in urbanization, sanitation, declining availability of groundwater, and increased environmental regulations. Many of these issues relate directly to agricultural water use and urban competition with crop and animal agriculture. Water is most importantly used for irrigation in agriculture which is key component to produce food. Irrigation accounts for more than 70% of total water withdrawals on a global basis (FAO, 2012a).Much of the current irrigation water comes from surface supplies, but 40% of the irrigated area uses groundwater sources (Siebert et al., 2010). Further climate change needs no introduction any more with wellknown effect on different aspect of life including agriculture and food production (Kang, 2009). Almost every part of the world evidenced its impact at different level and affected either positively or negatively. India being subtropical country is also sighting various changes in weather pattern and temperature rise that have effect on agriculture production. Water is necessary component for plant’s growth and development (Rijsberman, Page | 57
2008). Rainfall and irrigation are the two main sources of water in agriculture. Rain-fed crops contribute to 65% of world food production and the remaining 35% of food is produced from irrigation agriculture. Only 17% of total cultivated areas are irrigated (Rosegrant, 2010 and Hanjra, 2010). Thus, most of the land under cultivation depends on natural precipitation. Thus shifting in global rain pattern and increase in local temperature is leading to unprecedented drought in many crop production areas of the world (FAO, 2008). In northern part of India, almost once in every third year in western part and once in five years in eastern part, drought is experienced in past few years (NIDM UP, 2012). Normal rainfall was recorded in only in one year (2008-09) in past decades (947mm), and average annual rainfall decreased from 947mm to 737 mm. Further, of the total 10 years, 6 years received even below the decadal average i.e., 737mm (SAPCC, 2014). The distribution of seasonal rainfall has been highly erratic affecting cropping pattern, selection of crops and their varieties and over all agricultural production (Rosegrant 2010). Changes in climate variables like temperature increases can affect the hydrologic cycle by directly increasing evaporation of available surface water and vegetation transpiration. In past decades the average temperature of eastern utter Pradesh is rise. The minimum and maximum temperature is increase, which is around 2.0oC towards 2050. Whereas the average rainfall is also decrease in recants time period (IPCC, 2007). Rise in minimum temperature is appreciably higher than that maximum temperature, increasing in temperature and low rainfall causes drought prone condition in coming years in utter Pradesh, which is directly, affects on agriculture production (SPACC, 2014). To cope-up with coming vulnerability in agriculture production there are certain strategies which includes improvement in water use efficiency through irrigation, rain water harvesting and agronomic practices like mulching (Evans, 2008). Besides traditional efficient irrigation systems like drip irrigation, sprinkler irrigation recent research exploring possibilities towards use of certain environmentally friendly chemical which may increase water holding capacity of soil or may reduce the rate of transpiration (antitranspirants), which will make varieties withstand under water deficient condition and application can be managed on requirement bases. Which means when we need to slower down the transpiration when can apply antitranspirants and similar strategies can be adopted for increasing soil water retention capacity. Most of the crop plants presently cultivated lack physiological adaptation to hold out under water stress Page | 58
(Guillen et al., 2013). Present review seeks out the possibilities of use of antitranspirants and super absorbent. Antitranspirants Antitranspirants are the chemical compound which favours reduction in rate of transpiration from plant leaves by reducing the size and number of stomata and gradually hardening them to stress (Ahmed et al., 2014; El Khawaga, 2013). Nearly 95-98% of the water absorbed by the plant is lost in transpiration (Prakash and Ramachandran, 2000; Gaballah, 2014). It is a substance involved in increasing drought stress resistance. Foliar sprays markedly increase all growth parameters and. Relative Water Content and may reduce transpiration in three different ways: (1) some chemicals reduce the absorption of solar energy and decrease leaf temperatures and transpiration rate; (2) certain chemicals ( wax, latex or plastics) form thin colourless transparent films which decrease the escape of water vapour from the leaves but not affect the gasses exchange and (3) certain chemical compounds can control stomatal opening (by affecting the guard cells around the stomatal pore), thus decreasing the loss of water vapour from the leaves, (Besufkad et al., 2006). Water stress are substantially impacts yield. Hence, the application of Antitranspirant immediately prior to this stage may conserve water and improve grain set which could outweigh the photosynthetic limitations (Kettlewell et al., 2010). The three general types of antitranspirants are: (1) film-forming (2) stomatal-regulating and (3) reflective compounds. Film-Forming Compounds Film forming antitranspirant form a colourless film on the leaf surface which reduces the transpiration rate but have no effect on gasses exchange (Gale, 1961). Study of film on leaf surface by Slatyer and Bierhuizen (1964), Nitzshe (1991) resulted that the formation of film on surface of leaves reduces greater extent transpiration but a little bit affected on growth. Gale and Hagan (1966) also reported that mostly film-forming compounds are stop loss of water vapor and less effective to CO2 (Davenport et al., 1969) found it that coating of leaves by “CS-6432” alleviated photosynthesis more than transpiration when applied to plant. Past studies proved that the film forming antitranspirant is more effective in increasing grain yield and increasing photosynthesis in both, adverse or favourable condition. The higher leaf turgor in AT-sprayed WD (water deficit) plants is consistent with the notion that AT film decreases water loss and enables prolonged turgor maintenance under WD conditions In water stress condition leaf maintain its Page | 59
turgidity by applying antitranspirant on it and reduce the water loss in stress condition (Amor et al., 2010). Application of antitranspirant may improve growth and physiological response in water and high temperature stress in plants (Leskovar et al., 2008, 2011), water stress at a flowering stage affect the yield component of crop, it may be decrease, hence the foliar spray of antitanspirant is help in improving the photosynthesis and reduces the transpiration rate which causes a better production in crops (Kettlewell et al., 2010). Waggoner, 1962). Initial investigations professed that certain fungicides including phenyl mercury acetate (PMA), mercurized copper oxychloride, and copper oxychloride reduced the transpiration of tomato seedlings and potato plants (Blandy, 1957). Many effective stomatal-regulating compounds and also their concentrations used, the percent decrease in transpiration and stomatal condition; phenyl mercuric acetate, 8-hydroxyquinoline sulphate, and the mono-methyl ester of decenylsuccinic acid appeared to be the highly effective compounds (Zelitch, 1968). Since stomatal apertures affect CO2 diffusion as well as water vapour flow, photosynthesis and growth may be change when stomatal regulating compound are applied on leaves surface. If stomatal apertures are reduces in their size, transpiration should be also reduced by a greater amount than photosynthesis (Waggoner, 1965). Changes in transpiration (T) and photosynthesis (P) due to changes in stomatal path length (S) which was described by Zelitch and Waggoner (1962). Stomatal Regulating Compound Most of the anti transpirant functions as stomatal closer compound when it applied over leave. Some fungicide like phenyl mercuric acetate (PMA) and herbicide like Atrazine in low concentration serve as anti transpirant by inducing stomatal closing (Zelitch, 1961). These might reduce photosynthesis PMA was found to decrease transpiration than photosynthesis (Zelitch and Waggoner, 1962). Initial investigations professed that certain fungicides including phenyl mercury acetate (PMA), mercurized copper oxychloride, and copper oxychloride reduced the transpiration of tomato seedlings and potato plants (Blandy, 1957). Many effective stomatalregulating compounds and also their concentrations used, the percent decrease in transpiration and stomatal condition; phenyl mercuric acetate, 8hydroxyquinoline sulphate, and the mono-methyl ester of decenylsuccinic acid appeared to be the highly effective compounds (Zelitch, 1968). Since stomatal apertures affect CO2 diffusion as well as water vapour flow, photosynthesis and growth may be change when stomatal regulating Page | 60
compound are applied on leaves surface. If stomatal apertures are reduces in their size, transpiration should be also reduced by a greater amount than photosynthesis (Waggoner, 1965). Changes in transpiration (T) and photosynthesis (P) due to changes in stomatal path length (S) which was described by Zelitch and Waggoner (1962). Reflectance Compound White material which reflects solar radiation and increase the leaf albedo when they applied on leaves surface. Reflecting compounds do not cause blockage of stomatal pores when they are applied to the upper surfaces of leaves with stomata exclusively on the lower surfaces. Coating of reflectance type of chemical reduce the leaf temperature. It was experimentally proved that we diminished a transpiration rate up to 22-28% and also reduced leaf temperature 3o to 4o after coating of kaolinite (225 mg dm-2) (Hagan and Davenport, 1970). Some chemical compounds decrease leaf temperature by reflecting the solar radiation which cause retard transpiration rate and increase the water use efficiency of crops (Bittelli et al., 2001; Moftah and Humaid, 2005; Jifon and Syvertsen, 2003). Chemical which is Use as Antitranspirants 1) Chitosan 2) Kaolin 3) Abscisic acid (ABA) 4) Salicylic acid 5) Phenyl mercuric acetate 6) Cycocel 7) MgCO3 8) CaCO3, etc. Phenyl Mercuric Acetate
Phenyl mercuric acetate is example of such chemical compounds which affected on regulation of stomata or controlling the activity of stomata by changing their metabolic activity and permeability. Phenyl mercuric acetate is an organ mercury compound and in past research its activity reported as a antitranspirant when applied to the leaves surface (Ouda, 2007). In agriculture the phenyl mercuric acetate use as pesticide and it must be used with care since, it is mercury contain metabolic inhibitor. PMA is act as Page | 61
stomatal closer compound the optimum conc. may vary 10-3(strong) 10-5 (dilute). Betula papyrifera leaves treated with 10-3 m & 10-4 m PMA showed at least a certain degree of browning. By compression leaves treated with 105 m PMA had the same appearance as the control. The chlorophyll content PMA treated leaves is decreased by 25%.the action of magnesium carbonate as a refelectant, which helped in reducing heat load on leaves and increased penetration of more solar radiation into the canopy for photosynthesis (Gaballah and Moursy, 2004). Chitosan Chitosan is a nontoxic muco-polysaccharide with antimicrobial activity, which help plant to its defence system, it is found by de-acetylazation of chitin which is structural component of exoskeletons of crustaceans and some of the insects (Sanford, 2003). It is experimentally proved that chitosan increased the chlorophyll pigments under drought stress, its cleared that chitosan can induced the rate of photosynthesis and the accumulation of organic matter in wheat seedlings. Chitosan can enhance the root development in under water deficit condition, which help in absorbing more water to keep the moisture stable (Zhang et al., 2002). Chitosan has a strong potential application value in agriculture. Study of stomata under electron microscope and the histochemical analysis is proved that the coating of leaf by chitosan is close the stomata either partial or full and inhibit the water loss by leaf (Bittelli et al., 2001). Chitosan May take a part in ABA biosynthesis, which is responsible for stomatal closer in water defect condition in plants. The formation of chitosan films on the waxy surface of plant leaves prompts their use as antitranspirant. Chitosan works as both film-forming compound and physiological regulator of stomata via the ABA-dependent pathway (Kumar, 2013). Some film-forming compounds, like chitosan increase leaf surface reflectance, reducing absorption of radiant energy (heat), lowering leaf temperature, reducing water evaporation within the leaf and its diffusion to the surrounding atmosphere (referred to as transpiration). Stomata are the main route of water vapour export during plant growth. When emulsions of the synthetic compounds are sprayed on leaf surface, they form thin films and limit gas exchange by increasing stomatal resistance to the diffusion of water vapour (Jardin, 2012).
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Kaolin
Foliar application of kaolin has been demonstrated that it reduce the negative effects of water stress and to improve the physiology and productivity of plants (Rosati et al., 2006). The use of kaolin enhance the photosynthetic rate under water-stress conditions by increasing photosynthesis pigments in plants, under low water condition the application of kaolin may improve the photosynthetic response and increase the photosynthetic pigments (Monroy, 2012) and help in enhancing the water potential and osmotic potential in plants (Moftah and Humaid, 2005). It also increases the water-use efficiency of plants by 25% (Glenn et al., 2010). 1 to 6% kaolin treatment are gives better response in under unfavarable condition which inhibit the rate of transpiration and improve the yield quality (Jifon and Syvertsen, 2003). Several kaolin clay treatment are make a colourless film over the leaf surface which reflect the high wave length of solar radiation and retarded high temperature stress and water loss and also enhance the productivity of the plant (Mon, 2013). Kaolin is help in reduce heat effect and also protect leaf from sunburn, but it may slightly affect on ionic balance of soil. Application of kaolin is decrease leaf temperature 3 to 4oC and also mitigate the loss of water from leaf surface of 22 to 28% in many species and increase the leaf relative water content in plants and promotes the photosynthetic activity, which results increasing in biomass production (Khalil, 2012). Soil moisture percentage and antitranspirants significantly influenced the daily transpiration rate water use efficiency was increased at low soil moisture and by antitranspirants (Hagan and Davenport, 1970). The relative water content of leaves was reduced by low soil moisture, but was increased by the application of antitranspirants, which relieved plant water stress (Patil, 1976). Salicylic Acid (SA)
0.5% of salicylic acid increase the chlorophyll, no. of fruits, antioxidants enzymes which plays a defence mechanism against the moisture stress Page | 63
condition and all other parameters of growth (Ahmed, 2014). In earlier study it is reported by (Larque, 1978), the application of salicylates can mitigate the rate of transpiration and prevent the water loss from stomata (Mishra, 2015), the salicylic acid work as signal transduction whose activate the ABA activity and responsible for stomata closure in plants. This activity of stomata can effects on other physiological phenomenon like the stomatal closure may affect the photosynthetic process, SA shows its effect on chlorophyll, respiration, but most probably involved in regulation of photosynthetic reaction. It is demonstrated by Pancheva et al. (1996), 5 to 7 days of treatment of salicylic acid induced the CO2 level in leaf because of the stomatal closure (which effect the gassause exchange) and inhibit the activity of RuBP carboxylase which is effect on photosynthesis phenomenon, but 1 or less than 1 day treatment of SA did not show effect either on any physiological or biochemical parameters of crop. Activities of H2O2-metabolizing enzymes (such as CAT, POD and APX) and superoxidedismutating enzymes (SOD) were also modulated with SA in plants exposed to drought (Saruhan et al., 2012). SA (500 µM)-supplementation to drought stressed H. vulgare resulted in increased net CO2 assimilation rate due to increased stomatal conductance and eventually in increased plant dry mass (Habibi, 2012). Exogenously applied SA can modulate important enzymatic (including monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; GR; GSH peroxidase, GPX) and non-enzymatic (including GSH) components of AsA–GSH pathway, and also glyoxalase system (Gly I and Gly II) and decrease oxidative stress in drought-exposed plants (Abbaspour et al., 2016). Foliar application of SA (1.0 ìM) strengthened antioxidant defence system in drought-tolerant Z. mays cultivar to a great extent (vs. drought-sensitive cultivar; (Saruhan et al., 2012). Low membrane lipid peroxidation but increased plant height and dry mass, and less wilting of leaves were reported in drought-exposed and SA (0.5 mM)supplemented T. aestivum (Kang et al., (2012). Recently, SA-biosynthetic enzymes (such as CS and ICS) were not correlated with the SA level, but ortho-hydroxy-cinnamic (oHCA) was correlated with SA biosynthesis and played crucial role in drought tolerance in O. sativa (Pál et al., 2014). Abscisic Acid (ABA)
Abscisic is a plant growth substance, which play as a important part in response in environmental sttress and plant pathogens (Giraudat, 1998). Page | 64
When water potential of soil is decreased, it produced in roots and translocates to leaves where, it rapidly alters the osmotic potential of stomatal cells causing them to shrink and stomata to close. ABA induced stomatal closer retarded transpiration, thus preventing further water loss from the leaves in time of low water availability (Kang, 2002). 0.5 mg/l concentration of the ABA through prevent it from chilling stress, and also help in to decrease water loss in tomato plant and it also reduced the water stress effect in artichoke after applying it on surface of leaves by stomata closing (Takahashi et al., 1993). Cycocel
It is demonstrated that stomata show a significant role under water stress condition, to cope up from water stress stomata gets close for conserving water and this activity of stomata effect on gaseous exchange in PSII (Souza et al., 2004). This stomatal regulation under drought stress retard the actual photosynthetic rate. the application of cycocel (CCC) under water stress condition reduced the water loss from the areal part of plant and increase the yield and vegetative growth, which are helpful tools in reducing transpiration losses, is becoming popular (Rouhi et al., 2007). Cycocel with 500ppm concentration may help to mitigate the drought stress and significantly increase the photosynthetic pigment (Memari et al., 2011). Cycocel also act as growth inhibitor, foliar application of CCC reduce transpiration but, it may be lil bit affect the growth of plant (Pandey et al., 2003). Pinolene
CH3 Pinolene is an example of film forming antitranspirant, which did not increase water use efficiency of crop, but it can prevent water loss from arial part of plant. But, it is proved that the application of pinolene on grapes plant can increase both the WUE as well as sugar and anthocyanin content by which the quality of wine may also improve it may not possible with other substance at the same time. Pinolene helps in stomatal regulation and also decrease the photosynthesis (Brillante, 2013; Amor, 2010; Palliotti, 2010). Page | 65
Dyroton Drought has been considered as one of the most acute abiotic stresses presently affecting agriculture. Drought stress can significantly reduce photosynthesis and stomatal conductance, inhibit photosynthetic pigments synthesis and ultimately lead to reduction in growth of plants (Basu, 2016). The plant treated with 1-2% of the dyroton show very effective response in yield component of plant, and it increasing the nutritional value in fruits. It also prevents fruits with pathogenic response after postharvest (Faten, 2008). Effect of Antitranspirant Stomata is responsible for both the photosynthesis (by intake CO2 from atmosphere) as well as transpiration (loss of water) the antitranspirant is play a important role for reducing water loss and conserve the water but, it may be shows some effect on growth of plant (Obidiegwu et al., 2015). Some of the antitranspirant is not responsible for stomata closing when it applied to both the leaf surface upper and lower, but it may be responsible for the deduction of photosynthesis when light is not available in properly (Latocha et al., 2009). It is experimentally proved that the application of antitranspirant is helpful for the reduction of water loss and these chemical do not show adverse effect or harm plant’s intramural photosynthetic machinery. Phenyl mercuric acetate is a chemical, which is use as antitranspirant which close the stomata after application ant the intermediate concentration of PMA (1-3.5 M) is retard the rate of transpiration but it may reduce the dry matter of the plant. But, it is also reported that the higher concentration of PMA (10- 13.2 M) is shows the toxic effect on plant which retire the dry matter production and also increase transpiration (Abdullah, 2015). In general field crops are highly dependent or current photosynthesis for growth and final yield. Therefore, it is unlikely that currently available antitranspirant would increase yield of an annual crop unless crop suffers stressed from inadequate water and or a very high evaporative demand, particularly during a moisture sensitive stage of development. Sprayed stomata inhibiting or film forming antitranspirants on field grown sorghum under limited irrigation conditions, he found that grain yield increases 5 to 17% and application of antitranspirant just before the boot stage was more effective than later sprays (Fuahring, 1973). Disadvantages of Antitranspirants The possibility of using antitranspirants on grass to reduce both the frequency of irrigation and mowing is an attractive prospect which merits Page | 66
further investigation. The use of antitranspirants to decrease transpirational water losses from shrubs and trees on watersheds, where increased water yields may be more important than any harm caused by growth reductions, is a promising field for research and studies (Davenport, 1970). Growth reductions from the use of antitranspirants should not be disadvantageous once the oleanders have attained a height effective for screening headlight glare. Growth retarded growth is retarded by natural stomata1 closure when an untreated plant wilts, because of low soil water potentials and/or high evaporative demand. By slowing down the rate at which water is lost, antitranspirants will help to prevent or at least will delay wilting. The use of an antitranspirant, and the resulting reduction in transpiration (which is unlikely to exceed 30 per cent under field conditions), should not reduce the rate of mineral supply to the leaves sufficiently to retard growth. Present evidence suggests that antitranspirants will affect growth much less by altering leaf temperature and mineral nutrient supply than by retarding carbon dioxide supply to leaves. Super Absorbent Polymers Super absorbent polymers (SAP’s) are a unique group of materials that can absorb over a hundred times their weight in liquids and do not easily release the absorbed fluids under pressure. Super absorbents were first developed by the United States Department of Agriculture in the late 1960s. Early commercial versions first emerged in the United States in the early 1970s in the form of starch/acryonitril/acrylamide based polymers (Yamaguchi et al., 1987), with applications originally focused in the agriculture/horticulture markets, where they were used as a hydro gels to retain moisture in the surrounding soil during growing and transportation. Subsequently, cross-linked polyacrylates and modified cellulose ethers were also commercialized along with starch-grafted cross-linked polyacrylates. Polymers were used as structural materials for creating a climate beneficial to plant growth. One of the means to increase the water content in this soil is the use of super absorbent polymers as soil conditioners, which increase water retention in root zones region of the soil. In agricultural field, polymers are widely used for many applications. Although, they were used initially, just as structural materials, in the last decades, functionalized polymers revolutionized the agricultural and food industry with new tools for several applications. Super absorbents, depending on their source and structure are divided in Page | 67
two main groups of natural and synthetic. Natural-based SAPs are usually prepared through addition of some synthetic parts onto the natural substrates, e.g., graft copolymerization of vinyl monomers on polysaccharides, humus, polyuronids, Aljinic acids and starch (Lanthong et al., 2006; Li et al., 2007), cellulose (Suo et al., 2007), chitosan (Mahdavinia et al., 2004; Zhang et al., 2007), guar gum (Wang and Wang, 2009) and gelatin (Pourjavadi et al., 2007). Synthetic SAPs: The greatest volume of SAPs comprises full synthetic or of petrochemical origin. They are produced from the acrylic monomers, most frequently acrylic acid (AA), its salts and acrylamide (AM). Synthetic polymers with net type chemical bonds are not dissolvable in water. Synthetic SAPs usually are either polyveneyl alcoholes (–CH2OHOH–)n or polyacrylamides (–CH2CHCONH2–)n. SAPs used in agriculture are usually formulations commonly made of starch polyacrylamid graft copolymers (starch copolymers: SCP), venylalcohol-acrylic acids (copolymers: PVA), and acrylamids sodium acrylate copolymers (polyacrylamides: PAM) (Peterson, 2002). Synthetic polymers are used more than natural polymers because they are more resistant to biological degradation (Peterson, 2002). Physical Properties of Monomers for Preparing Super Absorbent Polymers The monomers, which are useful for making superabsorbent polymers are water-soluble monomers. Acrylic acid, methacrylic acid and 2acrylamido-2-methylpropanesulfonic acid are the principal ionizable monomers useful for making superabsorbent polymers. Other comonomers such as acrylamide and N isopropylacrylamide can also be incorporated into the polymer chain. For example, N-isopropylacrylamide imparts temperature sensitivity into the superabsorbent polymer. The useful cross-linkers include di-, tri-, or tetrafunctional, and can have mixed types of polymerizable groups such as methacrylate and allyl methacrylate. Mixed types of functional groups provide olefins with varying reactivity toward the main monomer. The mixed-functional cross-linkers can be used to control the incorporation of the cross-links during the polymerization. For example, the gel point of the polymerization can be made at lower conversion of monomers by using a cross-linker that is more reactive than the main monomer. Conversely, the gel point can be delayed to higher conversion of monomers by using a less reactive monomer compared to the main monomer (Mehr et al., 2008; Sannino et al., 2003). Variety of monomers, mostly acrylics, is employed to prepare SAPs.
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Acrylic acid (AA) and its sodium or potassium salts, and acrylamide (AM) are most often used in the industrial production of SAPs. On laboratory scales, however, number of monomers such as methacrylic acid (MAA), methacrylamide (MAM), acrylonitrile (AN), 2-hydroxyethylmethacrylate (HEMA), 2-acrylamido-2- methylpropane sulphonic acid (APMS), N-vinyl pyrrolidone (NVP), vinyl sulphonic acid (VSA) and vinyl acetate (VAc) are also used. In the modified natural-based SAPs (i.e., hybrid superabsorbents) trunk biopolymers such as cellulose, starch, chitosan, gelatin and some of their possible derivatives e.g., carboxymethyl cellulose (CMC) are also used as the modifying substrate (polysaccharide based SAPs section). N, N’methylene bisacrylamide (MBA) is most often used as a water soluble crosslinking agent. Ethyleneglycole dimethacrylate (EGDMA), 1, 1, 1trimethylolpropane triacrylate (TMPTA), and tetraalyloxy ethane (TAOE) are known examples of two-, three- and four-functional cross-linkers, respectively. Potassium persulphate (KPS) and ammonium persulphate (APS) are water soluble thermal initiators used frequently in both solution and inverse-suspension methods of polymerization. Redox pair initiators such as Fe2+ H2O2 (Fenton reagent) and KPS/APS-sodium bi sulphite are also employed particularly in the solution method (Demitri et al., 2008). Properties of Super Absorbent Polymer The super absorbent polymers are compound that absorb water and swell into many times of their original size and weight. They are lightly cross-linked networks of hydrophilic polymer chains and are used in soil to create a water reserve near the rhizosphere zone (roots) and benefit agriculture (Mehr and Kabiri, 2008; Han et al., 2010). The polymers, which have been used for agriculture purpose are safe and non-toxic and will eventually decompose to carbon dioxide, water and ammonia and potassium ions, without any residue (Mikkelsen, 1994; Trenkel, 1997). These also effective on reduction of drought stress effects. Super water absorbent polymers are found effective to control of soil erosion and water runoff, increasing infiltration capacity along with soil aggregate size (Wallace et al., 1986) and reducing irrigation frequency (Taylor et al., 1986). They also reducing soil bulk density, increasing water retention (Johnson, 1984), improving the survival of seedlings subjected to drought (Huttermann et al., 1999), lengthening shelf-life of pot plants (Gehring et al., 1980) and minimizing nutrient losses through leaching under highly leached conditions means increasing nutrient utilization efficiency (Lentz et al., 1998). Page | 69
Functionalized Polymers in Agriculture Synthetic polymers play an important role in agricultural uses as structural materials for creating a climate beneficial to plant growth e.g. mulches, shelters or green houses; for fumigation and irrigation, in transporting and controlling water distribution. However, the principal requirement in the polymers used in these applications is concerned with their physical properties; such as transmission, stability and permeability or weather ability; as inert materials rather than as active molecules. During the last few years, the science and technology of reactive functionalized polymers have received considerable interest as one of the most exciting areas of polymer chemistry for the production of improved materials (Petruzzelli et al., 2000). They have found widespread applications as reactive materials based on the potential advantages of the specific active functional groups and the characteristic properties of the polymeric molecules. Their successful utilizations are quite broad including a variety of fields, such as solid-phase synthesis, biologically active systems and other various technological uses (Ahmed, 1990). Uses of Super Absorbent Polymers in Agriculture The ability of SAPs to absorb large volumes of water and retain it within them has many practical applications in agriculture. The saturated hydraulic conductivity of the soil decreases significantly with increase in mixing ratio and swelling property of the SAP. Its swelling reduces the largest pores in the soils, especially in the sandy soils (Koupai et al., 2008). The expansion of soil-SAP mixture increases with increase in mixing ratio and swelling property of SAP (Andry et al., 2009). Also, the application of SAPs to the soil increases both saturated and residual water content, water holding capacity and available water content. SAPs can be used in the same way as mulch, to help the soil to retain more moisture and also for longer (Buchholz and Graham, 1997). Amendment of SAPs also affects other properties of soil like infiltration rates, bulk density, soil structure, compaction, soil texture, aggregate stability, crust hardness and evaporation rates. The bulk density of the soil decreases with increase in application rates of SAPs (Bai et al., 2010). Application of SAPs to soil also reduces infiltration and thus avoids potential loss to deep percolation. Further, the infiltration reduction produced did not decline with decreasing treated soil layer thickness. The expansion and contraction of SAPs in soil during the cycle of water absorption and evaporation helps to improve air content in the soils, especially in clayey
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soils. SAPs application in soils greatly reduces irrigation induced erosion and soil water seepage and further increases the uniformity of furrow water applications. Another advantage of amendment of SAP is that it greatly reduces the irrigation frequency particularly in coarse-textured soils. This property could be best utilized for water management practices in arid and semi-arid regions. The SAPs are also biodegradable and further their products do not harm the microbial community present in the soil. SAP amendment increases yield and water use efficiency of plants that is increase in plant biomass. SAP amendment aides plant growth by increase. Prolong survival of plants under water stress and drought conditions (Dorraji, 2010). Limitations of Super Absorbent Polymer in Agriculture SAPs are quite fragile and tend to break apart easily thereby losing their water retention property. Further SAPs can also dehydrate rapidly in a matter of hours thus losing their absorbed water (Kim and Nadarajah, 2008). The water absorption of SAPs greatly reduces in the soils as SAPs are under pressure and unable to swell and take in water. The water absorption of SAPs in soils further decreases due to formation of additional crosslink’s with certain ions like Ca2+ and Al3+ present in the soil. The water absorption of the SAP also decreases with increase in salinity of irrigation water The SAPs in soils releases water with increase in temperature and this water could be potentially lost to deep percolation (Andry et al., 2009). Further, it could be inferred that the effectiveness of SAP decreased on rewetting and can affect the hydraulic properties of soil only if applied in higher application rates (Geesing and Schmidhalter, 2004). The efficacy of the SAP decreases over a period of time and to compensate for these loses, higher application rates are required.This factor affects the economic value of crops grown on fields amended with SAP. References 1.
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Superabsorbent
Polymer
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Chapter - 5 Role of Flavonoids like Green Tea, Citrus Fruits (Antioxidant)
Authors Anjali Dahiya Deptartment of Biotechnology, DCRUST, Murthal, Haryana, India Ritu Khasa Corresponding Author Deptartment of MBBB, CCS HAU, Hisar, Haryana, India Ritu Saini Department of Chemistry and Biochemistry, CCS HAU, Hisar, Haryana, India Harnek Saini Department of Biotechnology, UIET, Kurukshetra, Haryana, India
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Chapter - 5 Role of Flavonoids like Green Tea, Citrus Fruits (Antioxidant) Anjali Dahiya, Ritu Khasa, Ritu Saini and Harnek Saini
Abstract Flavonoids & other polyphenolics, Vitamins C & E, and carotenoids are the most common dietary antioxidants. Antioxidants are molecules capable of reducing the causes or effects of oxidative stress. Oxidative stress can be caused by environmental factors, disease, infection, inflammation, aging (ROS production). ROS or “reactive oxygen species” include free radicals and other oxygenated molecules resulting from these factors. The body produces some endogenous antioxidants, but dietary antioxidants may provide additional line of defense. Many herbs and botanicals also contain antioxidants. Keywords: Flavonoids, ROS, Free radicals, Cancer, Antioxidant. Flavonoids - Introduction Flavonoids belong to a very vast group of plant secondary metabolites with variable phenolic structures and are found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. These are water soluble pigment. In plants, flavonoids are performing a variety of functions including pollination, seed dispersal, pollen tube growth, resorption of mineral nutrients, tolerance to abiotic stresses, protection against ultraviolet etc. The antioxidant effect of flavonoids can reside both in their radical-scavenging activity or in their metal-chelating properties, of which the former may dominate. Flavonoids as Antioxidants Flavonoids are especially effective because of structural features including:
Conjugation to further stabilize radicals.
ortho- dihydroxysubstituted B ring allows for chelation of pro-oxidant metal ions.
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(Fe2+, Fe3+, Cu2+, etc.)
α,β-unsaturated ketone and 3-OH on C-ring
Sources of Antioxidants in the Diet
Free Radicals Atomic or molecular species with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly reactive, so radicals are likely to take part in chemical reactions. Free radicals play an important role in a number of biological processes, some of which are necessary for life, such as the intracellular killing of bacteria by neutrophil granulocytes. Free radicals have also been implicated in certain Page | 82
cell signalling processes. The two most important oxygen-centered free radicals are superoxide and hydroxyl radical. They are derived from molecular oxygen under reducing conditions. However, because of their reactivity, these same free radicals can participate in unwanted side reactions resulting in cell damage. Free Radicals and Cancer Many forms of cancer are thought to be the result of reactions between free radicals and DNA, resulting in mutations that can adversely affect the cell cycle and potentially lead to malignancy. Some of the symptoms of aging such as atherosclerosis are also attributed to free-radical induced oxidation of many of the chemicals making up the body. Reactive Oxygen Species (ROS) Reactive Oxygen Species (ROS) include oxygen ions, free radicals and peroxides both inorganic and organic. They are generally very small molecules and are highly reactive due to the presence of unpaired valence shell electrons. ROSs form as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling. However, during times of environmental stress ROS levels can increase dramatically, which can result in significant damage to cell structures. This cumulates into a situation known as oxidative stress. Cells are normally able to defend themselves against ROS damage through the use of enzymes such as superoxide dismutases and catalases. Small molecule antioxidants such as ascorbic acid (vitamin C), uric acid, and glutathione also play important roles as cellular antioxidants. Similarly, polyphenol antioxidants assist in preventing ROS damage by scavenging free radicals. What Do Antioxidants Do?
Prevent formation of ROS.
Inhibit xanthine oxidase, COX, LOX, GST monooxygenases, chelate metals.
Scavenge/remove biomolecules.
Aid the human body’s natural defenses.
ROS
before
Upregulate superoxide glutathione peroxidase.
Repair oxidative damage.
Eliminate damaged molecules.
Prevent mutations.
they
dismutase
can
(O2-.),
damage
catalase
important
(H2O2),
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Phenolics Group of secondary plant products or compounds. Composed of a hydroxyl group attached to an aromatic ring. A broad range of compounds found in all components of plants: leaves, flowers, fruit etc. Comprised of many groups: Flavonoids, Tannins, Lignin etc. All very chemically diverse! Historical Perspective of Flavonoids In 1930, a new substance was isolated from oranges that can reduce the capillary permeability and is believed to be a member of a new class of vitamins hence designated as vitamin P, however, later on this substance was identified as a flavonoid (rutin). Flavonoids drew greater attention with the decreased incidence of cardiovascular diseases, in spite of a greater saturated fat intake in Mediterranean population, which was associated with red wine consumption. Core Structures and Nomenclature The nomenclature of flavonoids proper is straight-forward with the aromatic ring A condensed to the heterocyclic ring C and the aromatic ring B most often attached at the C2 position. The various substituents are listed first for the A and C ring and - as primed numbers - for the B ring (note that the numbering for the aromatic rings of the open-chained precursor chalcones is reversed). The Biosynthesis of Flavonoids They are synthesized from the aromatic amino acids-phenylalanine and tyrosine, together with acetate units Phenylalanine and tyrosine are converted to cinnamic acid and parahydroxycinnamic acid, respectively, by the action of phenylalanine and tyrosine ammonia lyases Cinnamic acid (or parahydroxycinnamic acid) condenses with acetate units to form the cinnamoyl structure of the flavonoids (Fries rearrangement). A variety of phenolic acids, such as caffeic acid, ferulic acid, and chlorogenic acid, are cinnamic acid derivatives. There is then alkali-catalyzed condensation of an ortho-hydroxyacetophenone with a benzaldehyde derivative generating chalcones and flavonones as well as a similar condensation of an orthohydroxyacetophenone with a benzoic acid derivative (acid chloride or anhydride), leading to 2-hydroxyflavanones and flavones. Biotransformation of flavonoids in the gut can release these cinnamic acid (phenolic acids) derivatives In terms of their biosynthesis, the phenyl propanoid pathway produces a range of secondary metabolites such as phenolic acids, lignins, Page | 84
lignans and stilbenes using phenyl alanine and tyrosine as the precursor. After tannins, flavonoid glycosides are by far the most common dietary sources of flavonoids. Usually 110–121 mg/day of flavonoids has been recommended as a healthy diet for an adult. Intake, Absorption, Conjugation, and Toxicity of Flavonoids Intake The average daily flavonoid intake in the India is estimated to be 23 mg/d. Intakes of flavonoids exceed those of vitamin E and -carotene, whereas the average intake of vitamin C is 3 times higher than the intake of flavonoids. Flavonoid intakes seem to vary greatly between countries; the lowest intakes (2.6 mg/d) are in Finland and the highest intakes (68.2 mg/d) are in Japan. Quercetin is the most important contributor to the estimated intake of flavonoids, mainly from the consumption of apples and onions. Potential Molecular Sites of Metabolic Modification
Conjugation It is generally accepted that the conjugation pathway for flavonoids (catechins) begins with the conjugation of a glucuronide moiety in intestinal cells. The flavonoid is then bound to albumin and transported to the liver. The liver can extend the conjugation of the flavonoid by adding a sulfate group, a methyl group, or both. The addition of these groups increases the circulatory elimination time and probably also decreases toxicity. There are several possible locations for the conjugates on the flavonoid skeleton. The type of conjugate and its location on the flavonoid skeleton probably determine the enzyme-inhibiting capacity, the antioxidant activity, or both of the flavonoid. Toxicity
Flavonoids are toxic to cancer cells or to immortalized cells, but are not toxic or are less toxic to normal cells.
Flavonoids might play a role in the prevention of cancer Page | 85
Working Mechanisms
Antioxidative effects
Nitric Oxide
Xanthine Oxidase
Direct radical scavenging
Interaction with other enzyme systems
Clinical Effects
Antiatherosclerotic effects
Antiinflammatory effects
Antitumor effects
Antiosteoporotic effects
Antiviral effects
Molecular Mechanism of Anti-Cancer Effect
Inhibition of PKs
Inhibition of prooxidant enzymes
Modulate the metabolism of carcinogen
Anti-oxidant properties
Anti-angiogenesis
Induce apoptosis and cell cycle arrest
Inhibition of PKs Phosphorylation of proteins at OH groups of serine, threonine and tyrosine residues is an important mechanism of intracellular signal transduction involved in various cellular responses including the regulation of cell growth and proliferation. The reaction makes use of ATP as a phosphate donor and is catalyzed by protein kinases. For instance, growth factor hormones bind to extracellular domains of large transmembrane receptors that display a tyrosine kinase moiety in their intracellular portion. As a consequence of hormone–receptor binding, the receptor dimerizes and becomes active in the phosphorylation of proteins close to the membrane, thereby triggering a large number of signaling pathways themselves involving other PKs, such as PKC, a Ser/Thr PK, and mitogen-activated PKs (MAPKs). On the other hand, each phase of the cell cycle, during which the DNA is replicated and the chromosomes built and then separated, is characterized by intense bursts of phosphorylation controlled by highly Page | 86
regulated kinases called cyclin-dependent kinases (CDKs). A possible mechanism for the potential anti-carcinogenic effects of flavonoids could be their ability to inhibit various PKs, thereby inhibiting signal transduction event of cell proliferation. The isoflavone genistein has been shown to inhibit the epidermal growth factor (EGF) receptor in the submicromolar range by competing with ATP for its binding site. Similarly, butein (2’, 3, 4, 4’-tetrahydroxychalcone) appears as a specific inhibitor of tyrosine kinases acting competitively to ATP and non-competitively to the phosphate acceptor and having no affinity for Ser/Thr PKs such as PKC and the cAMP dependent PKA. Recently, PKC was shown to be efficiently inhibited by flavones and flavonols having a 3’, 4’-dihydroxy substitution on the B ring phosphoinositide 3-kinase (PI3-K), a lipid kinase catalyzing phosphorylation of inositol lipids at the D3 position of the inositol ring to form new intracellular lipid second messengers is also inhibited by flavonoids. Cells that have various flavonoids can cause cell cycle arrest in correlation to their ability to inhibit CDKs. Flavonoids can also modulate the activity of MAPKs as a possible mechanism for their potential anti-neurodegenerative action and protection against autoimmune, allergic, and cardiovascular diseases Inhibition of Prooxidant Enzymes Formation of reactive oxygen species (ROS) is a major step in the tumor promotion and progression stages. NADPH oxidase I (NOX 1), an enzyme that produces superoxide is overexpressed in colon and prostate cancer cell lines, while its downregulation reverses tumor growth. ROS act as secondary messenger in several pathways that lead to increase in cell proliferation, resistance to apoptosis, activation of proto-oncogenes such as cFOS, cJUN and cMyc. In human hepatoma cells, ROS modulate the expression of cFOS and cJUN through PKB pathway. Lipoxygenases (LOX), cycloxygenases (COXs), and xanthine oxidase (XO) are metalloenzymes whose catalytic cycle involves ROS such as lipid peroxyl radicals, superoxide, and hydrogen peroxide. LOXs and COXs catalyze important steps in the biosynthesis of leucotrienes and prostaglandins from arachidonic acid, which is an important cascade in the development of inflammatory responses. XO catalyzes the ultimate step in purine biosynthesis, i.e., the conversion of xanthine into uric acid. XO inhibition is an important issue in the treatment of gout. Flavonoids may exert part of their anti-oxidant and anti-inflammatory activities via direct inhibition of these prooxidant enzymes (LOXs, COXs, and XO). Typically, interpretation of the inhibition studies is complicated because of the possible combination of distinct inhibition mechanisms: formation of non-covalent enzyme-inhibitor complexes, direct scavenging by flavonoid Page | 87
anti-oxidants of ROS inside or outside the catalytic pocket (with simultaneous oxidation of the flavonoids), chelation of the enzyme metal centers by the flavonoids, and enzyme inactivation by reactive aryloxyl radicals, quinones, or quinonoid compounds produced upon flavonoid oxidation that may eventually form covalent adducts with the enzyme Anti-Oxidant Properties In addition to enzymatic oxidation, flavonoid oxidation can take place via autoxidation (metal-catalyzed oxidation by dioxygen) and ROS scavenging. The former process can be related to flavonoid cytotoxicity (ROS production) while the latter is one of the main anti-oxidant mechanisms. Both processes may be modulated by flavonoid–protein binding. Albumin–flavonoid complexes with an affinity for LDL could act as the true plasma antioxidants participating in the regeneration of αtocopherol from the α-tocopheryl radical formed upon scavenging of LDLbound lipid peroxyl radicals. Anti-Angiogenesis Angiogenesis, the formation of new blood vessels, is an important process which is regulated by endogenous angiogenic and angiostatic factors. Any alteration in this tightly regulated process can lead to a persistent and uncontrolled growth and metastasis of tumors. Flavanoids have been reported as angiogenesis inhibitors. These inhibitors can cause lack of diffusion of nutrients and oxygen to rapidly growing cancerous cells due to anti-angiogenic properties and hence lead to cell death. Angiogenesis inhibitors can interfere with various steps in angiogenesis, such as the proliferation and migration of endothelial cells and lumen formation. A possible mechanism could be inhibition of protein kinases. These enzymes are implicated to play an important role in signal transduction and are known for their effects on angiogenesis. Genistein is a potent inhibitor of angiogenesis in vitro and thus could have therapeutic applications in the treatment of chronic neovascular diseases including solid tumor growth and inhibition of neovascularization of the eye by genistein has been reported. Isoflavonones (genistein, genistin, daidzein, and biochanin A) also inhibit growth of murine and human bladder cancer cell lines by inducing cell cycle arrest, apoptosis, and angiogenesis. Luteolin has been found to inhibit VEGF-induced angiogenesis; inhibition of endothelial cell survival and proliferation by targeting phosphatidylinositol-3-kinase action. Inhibition of VEGF release by flavonoids, tocopherols, and lovastatin in models of neoplastic cells suggests a novel mechanism for mammary cancer
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prevention. Hispidulin targets the VEGF receptor 2-mediated PI3K/Akt/mTOR signaling pathway in endothelial cells, leading to the suppression of pancreatic tumor growth and angiogenesis. Induce Apoptosis and Cell Cycle Arrest Apoptosis is a programed cell death to eliminate damaged or unwanted cells. It is regulated by a variety of genes that can either promote apoptosis or can favor cell survival in response to internal or external stimuli. Dysregulation of apoptosis could play a critical role in oncogenesis. Among these genes, the tumor suppressor p53 plays a pivotal role in controlling the cell cycle, apoptosis, genomic integrity, and DNA repair by acting as Transactivator or as Transrepression. After activation, p53 can bind to regulatory DNA sequences and activate the expression of genes involved in cell cycle inhibition (p21, reprimo, cyclin G1, GADD45), apoptosis (PERP, NOXA, PUMA, p53AIP1, ASPP1/2, Fas, BAX, PIDD) and genetic stability (p21, DDB2, MSH2, XPC). EGCG also activated p53 and BAX in breast carcinoma cells. Genistein induced G2/M arrest and apoptosis in human malignant glioma cell lines by activating p53 and p21. In addition to p53, mammalian cells contain two closely related proteins, p63 and p73. EGCG induces apoptosis by activating p73-dependent expression of a subset of p53 target genes. Flavonoids have been found to suppress activator protein- 1 (AP-1) activation and modulate AP-1 target genes. AP-1 is a group of dimeric leucine zipper proteins consisting of Jun (c-Jun, JunB, JunD), Fos (c-Fos, FosB, Fra-1, and Fra-2), Maf (c-Maf, MafB, MafA, MafG/F/K, and Nrl), and ATF (ATF2, LRF1/ATF3, B-ATF, JDP1, JDP2) subfamilies. These proteins form either homo- or heterodimers and bind either to AP-1 DNA recognition elements (50-TGAG/CTCA-30) or to cAMP response elements and activate their target genes. Some of the biologic effects of AP1 are mediated by gene repression. AP-1-regulated genes include important modulators of invasion and metastasis, angiogenesis, proliferation, differentiation, and survival. Activation of various tyrosine kinases leads to phosphorylation, dimerization, and nuclear localization of the signal transducers and activators of transcription (STAT) proteins, binding to specific DNA elements and direct transcription. Constitutive activation of STAT3 and STAT5 has been implicated in multiple myelomas, lymphomas, leukemias, and several solid tumors. luteolin inhibited phosphorylation of STAT3, which targeted it for proteosomal degradation and inhibited the expression of cyclin D1, survivin, Bcl-x(L), and VEGF. Quercetin inducing G2/M phase cell cycle arrest and mitochondrial apoptosis through a p53dependent mechanism. Similarly fisetin inhibited the proliferation of bladder Page | 89
cancer cells by inducing apoptosis and blocking cell-cycle progression in the G0/G1 phase. It significantly increases the expression of p53 and p21 proteins and decreases the levels of cyclin D1, cyclin A, CDK4 and CDK2, thereby contributing to cell cycle arrest. In addition, fisetin increased the expression of Bax and Bak but decreased the levels of Bcl-2 and Bcl-xL and subsequently triggered mitochondrial apoptotic pathway. Wheat Germ and Whole Grains Tocotrienols are naturally occurring isoprenoid compounds highly enriched in palm oil, rice bran, oat, wheat germ, barley and rye. Tocotrienols have antioxidant properties as well as potent anticancer properties. Fibers in the bran is colon-protective Spinach Leaves Spinach leaves, containing several active components, including flavonoids, exhibit antioxidative, antiproliferative, and antiinflammatory properties in biological systems. Spinach extracts have been demonstrated to exert numerous beneficial effects, such as central nervous system protection and anticancer and antiaging functions. The glycolipids fraction from spinach is potentially a source of food material for a novel anticancer activity Strawberry The most abundant phytochemicals are ellagic acid, and certain flavonoids: anthocyanin, catechin, quercetin and kaempferol. Compounds in strawberries have demonstrated anticancer activity in several different experimental systems, blocking initiation of carcinogenesis, and suppressing progression and proliferation of tumors. Citrus Fruits Epidemiological and animal studies suggest that flavonoids (hesperidin) have a protective effect against cardiovascular diseases and some types of cancer. Citrus fruits contain not one but multiple cancer chemopreventive agents like limonoids, ascorbic acid (vitamin C), carotenoids (especially β-carotene), folate, flavonoids and dietary fibres, and have been shown to prevent a variety of cancers and cardiovascular diseases. Limonoids are a prominent group of secondary metabolites in citrus fruit with anticancer effect Green Tea The green tea phenolic compounds of highest concentration are gallic acid (GA), (–)- gallocatechin (GC), (+)-catechin (C), (–) -epicatechin (EC), Page | 90
(–)-epigallocatechin (EGC), (–)- epicatechin gallate (ECG), (–)epigallocatechin gallate (EGCG), p-coumaroylquinic acid (CA), and (–)gallocatechin-3-gallate (GCG), with EGCG being the most abundant by weight. Green tea also contains condensed and hydrolyzable tannins. Green tea has the highest concentration of polyphenols, which can induce apoptotic cell death in cancer better than other teas. Increase the activity of antioxidant enzymes. Inhibit cancer by blocking the formation of cancer-causing compounds and suppressing the activation of carcinogens. The major polyphenols in green tea are flavonoids (catechin, epicatechin and so on). Some Valuable Advice
Enjoy fruit as a snack or dessert
Add fruits to breakfast cereal
Try whole-grain or multigrain toast and sandwiches
Eat three different colors of vegetables with dinner
Fill half of the dinner plate with vegetables
Include salad with lunch
References 1.
Joshua D, Lambert Ryan J, Elias. The antioxidant and pro-oxidant activities of green tea polyphenols: A role in cancer prevention. Archives of Biochemistry and Biophysics. 2010; 501:65-72.
2.
Priya Batra, Anil K. Anti-cancer potential of flavonoids: recent trends and future Perspectives, 2013. DOI 10.1007/s13205-013-0117-5
3.
Hollman PCH, Katan MB. Absorption, metabolism, and bioavailability of flavonoids. In: Rice-Evans CA, Paker L (eds) Flavonoids in health and disease. Marcel Dekker Inc, New York, 1998, 483-522.
4.
Hollman PCH, Katan MB. Dietary flavonoids: intake, health effects and bioavailability. Food Chem Toxicol. 1999; 37:937.
5.
Kurisawa M, Chung JE, Kim YJ, Uyama H, Kobayashi S. Amplification of antioxidant activity and xanthine oxidase inhibition of catechin by enzymatic polymerization. Biomacromolecules. 2003; 4:469-471.
6.
Roy AM, Baliga MS, Katiyar SK. Epigallocatechin-3-gallate induces apoptosis in estrogen receptor-negative human breast carcinoma cells via modulation in protein expression of p53 and Bax and caspase-3 activation. Mol Cancer Ther. 2005; 4:81-90.
7.
Schroeter H, Spencer JP, Rice-Evans C, Williams RJ. Flavonoids protect neurons from oxidized low-density-lipoprotein- induced apoptosis involving c-Jun N-terminal kinase (JNK), c-Jun and caspase3. Biochem J. 2001; 358:547-557. Page | 91
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Chapter - 6 Soil Formation in Toposequences
Author Prava Kiran Dash Ph.D Scholar, Department of Soil Science and Agricultural Chemistry, College of Agriculture, Orissa University of Agriculture and Technology, Bhubaneswar, Odisha, India
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Chapter - 6 Soil Formation in Toposequences Prava Kiran Dash
Abstract The term toposequence refers to a series of soils which vary with respect to their morphological, physico-chemical and other characteristics only because of the difference in topography. The topography influences soil formation through water, temperature, soil erosion and micro-climate relations. The spatial changes in the forms of relief comprising varied toposequences govern the input of solar radiation (heat) and moisture (precipitation) which subsequently interacts between them giving rise to a sharply differing hydrothermal regime in the reacting microenvironments along the toposequences (Sarkar, 2003). Great difference in the soil properties such as morphological, physico-chemical, available macro and micro nutrient status, soil genesis and classification of different land types starting from hill slope and ending at stream terrace land have great bearing in soil management and productivity of different crops along a catena or toposequence. The red soil occurs on the top of the mounds, followed by yellow soils, the brown soil down the slopes; and the black soil in the valleys (Mishra, 1995). The depth of the solum increases from top to bottom slopes with soils acidic to alkaline in reaction, structureless to blocky, and sandy loam to clayey in texture. Drainage conditions, differential transport of eroded materials, leaching, translocation and redeposition of mobile soil constituents influence the genesis of the soils. Percentages of clay, pH, organic carbon, Cation Exchange Capacity (CEC), Percentage Base saturation and Exchangeable Sodium Percentage (ESP) has increasing trend along the slope, which could chiefly be attributed to the translocation of finer soil particles and bases down the slope through runoff and their subsequent deposition in the lower topographic positions. Physical properties of soils of low land topography are with relatively low bulk density and infiltration rate with relatively high percentage porosity and water holding capacity. Soil fertility status with respect to both macro and micronutrients were higher in low lying topographic positions which could be attributed to accumulation of
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higher amount of clay, cations and organic matter resulting from leaching and runoff from higher topographic positions as a result of intensive rain fall. Soils also vary with respect to soil genesis and classification along a toposequence. Soils vary with respect to Soil Taxonomy even at order level found in most of the transects. Erosion and water logging are the most important constraints in upland and low land topographic positions respectively. As there are great differences found along toposequences, land use planning can be made accordingly in order to increase crop productivity as well as to prevent soil erosion. Uplands can be used for growing plantation crops, tree crops, orchards, agroforestry, agri-horti-silviculture, planting Vetiver and Sisal (Agave Sisalana), construction of buildings, roads railway tracks etc.; that of medium lands can be used for growing oilseeds, pulses, legumes and field crops; that of low lands which are mostly characterised by impeded drainage and high water table can be used for low land paddy cultivation and pisciculture. Keywords: Toposequence, catena, soil taxonomy Soil Formation in Toposequences Introduction Soil is the most wondrous gift of nature to human society. If there is life on the planet earth, it is because there is thin layer of soil on its top. Soil originates from weathering of earth’s lithosphere. Wearing a way of rocks is a slow activity. It takes nature hundreds to thousands of years for transforming rocks to soil (Brady and Weil, 2014) [1]. Several factors act simultaneously for the process of soil formation known as ‘factors of soil formation’. The factors of soil formation interact and complement each other. V. V. Dokuchaev (1889) [2] was the first to show that soil forms in a definite pattern on the landscape and develop distinct horizons under the influence of parent material, climate and organism which he put as: S=f(p, cl, o). Jenny (1941) [3] added two more factors including relief & time. He stated that all five soil forming factors act simultaneously at one point on the surface to produce soil are: climate, organism, relief, parent material & time. It may be represented as S=f (cl, o, r, p, t.). [Where, S=any soil property; f= function of or dependent on; cl=climate; o=biosphere (flora and fauna); r=relief or topography; p=parent material; t=time;-unexpected/unidentified factors]. Page | 96
J.S. Joffe (1949) [4] further classified into two groups i.e. active and passive soil forming factors [Active soil forming factors are climate, biosphere (flora and fauna) and passive soil forming factors are relief or topography, parent material and time]. Relief or topography plays a very important role in determining the nature and properties of soil.
V. V. Dokuchaev (1846-1903)
Hans Jenny (1899-1992)
Jacob S Joffe
Geoffrey Milne
Concept of Catena The realisation that- for a sequence of topographically related soils which have comparable parent material, climate and age, but show different characteristics owing to variation only in relief and drainage and particular slope forms were associated with particular soil sequences led to the formation of the concept of ‘catena’. Geoffrey Milne (1935) an American scientist while studying the soils of South Africa originally defined a catena as 'a unit of mapping of soils which while they fall widely apart in a natural system of classification on account of fundamental and morphological differences, are yet linked in their occurrence by conditions of topography and are repeated in the same relationships to each other where the same conditions are met with’ (Milne 1935, p.197) [5]. Toposequence The term toposequence consists of two words; one is ‘topo’, and the other is ‘sequence’. Here, ‘topo’ refers to topography and ‘sequence’ refers to series or serial. So, in soil science the term toposequence refers to a series of soils which vary with respect to their morphological, physico-chemical and other characteristics only because of the difference in topography. The relief or topography denotes configuration of the land surface and is described in terms of differences in elevation, slope, and landscape positionin other words, the lay of the land. Hence, toposequence is a type of catena, in which the differences among the soils results almost entirely from the influence of topography because the soils in the sequence all share the same parent material and have similar conditions regarding climate, vegetation, and time (Brady and Weil, 2014) [1]. Page | 97
The topography influences soil formation through water, temperature, soil erosion and micro-climate relations. The spatial changes in the forms of relief comprising varied toposequences govern the input of solar radiation (heat) and moisture (precipitation) which subsequently interacts between them giving rise to a sharply differing hydrothermal regime in the reacting microenvironments along the toposequences (Sarkar, 2003) [6]. For instance, a nearly level to very gently sloping upland topography representing well drained ecosystem, receives proportionate input of heat and moisture and thus generates a normal hydrothermal regime. The microenvironment thus retains proportionate quanta of temperature and moisture regimes in the regolith governing pedogenic processes and kinds of soil formation. In undulating topography, input of heat and moisture differs along the toposequence. A steep slope will result in excess runoff and the soil will take in little moisture while heat input will be normal. However, the toe end of the slope will receive runoff in addition to the input of moisture from precipitation and heat. Thus, the hydrothermal environment generated along a steep slope or a rolling topography will experience low moisture and more drought conditions, whereas the hydrothermal condition at the toe end of the slope will be characterised by a humid pedo-climate. Hence, the attributes of relief brings about local modifications in the climatic environment either singly or altogether which in turn will affect the pedogenic processes producing different kinds of soils within the same macroclimatic region. Besides such indirect effects, the relief may be directly responsible for physical alteration of the landscape. The different attributes of relief like degree of slope, aspects and elevation when subjected to direct impact of degradational forces like heat, water and wind will be subjected to different degrees of denudation cycles over the time. Such denudation cycles may include several erosion hazards leading to soil loss and mass waste changing the shape or geomorphic feature of the landscape itself. Thus, there will be new evolution of landscape with specific toposequences comprising of old as well as new soils, developed under changed environments (Sarkar, 2003) [6]. Out of total rainfall, a part of it infiltrates downward while the rest gets lost as surface runoff. In mountain areas most of the water is lost through runoff carrying soluble and insoluble materials, which ultimately gets deposited at the foot hills. Thus, in this way the soils formed at the foot hills are different from the upper part of the mountain. Different Types of Topography Within the particular relief form there are several land forms. Particularly in mountainous region slope facet and slope sequences exists Page | 98
which exhibits different properties of soil formation. For example, soils of the hilltops can be different from soils of the lower slopes and soils of the low lying valley bottom. Generally in any area except coastal areas (which are very near to the sea shores) we find toposequence where there is a hill, hill slope, ridge, valley, levee and stream terrace land. Ridges are found at the bottom of hill, which is also sometimes called as upper part of the upland. The lands very close to the streams or rivers, which are now subjected to flooding, are called as stream terrace land. The soils which were earlier subjected to flooding, but at present not flooded and situated at some distance from the river or stream next to stream terrace land are called as levee. The bottom land in between the hill and levee is known as valley. Optimal use of land is arrived at, when land use goals are realised with minimal negative effect. This can be achieved by integrating the experience of the farming community with scientific knowledge on the soil resource. Ever since, a number of concepts have come into existence through a process of soil study, among which toposequence concept is one of them. This concept needs to be studied thoroughly well, to show its practical relationship with land use and land use planning. A catena or toposequence in a hilly terrain not only gives a panoramic view which is a feast to the eyes but also, the great difference in the soil properties such as morphological, physico-chemical properties of different land types starting from hill slope and ending at stream terraced land have great bearing in soil management and productivity of different crops. The prominent types of topography designation as per FAO guidelines 1990 are as follows. Slope Class (Land Surface)
% slope
Level to nearly level
0-1
Very gently sloping
1-3
Gently sloping
3-8
Moderately sloping .
8-15
Moderately steep sloping :
15-30
Steeply sloping
30-50
Very steeply sloping
>50 (FAO guidelines 1990) [7]
Some modifications of prominent types of topography depending upon the Indian conditions made by Sehgal et al, (1987), are as follows: Land Surface
% Slopes
Flat to almost flat
0-2 Page | 99
Gently undulating
2-5
Undulating
5-10
Rolling
10 – 15
Hilly
15 – 30
Steeply dissected
>30% with moderate range of elevation (30% with great range of elevation (>300 m) (Sehgal et al, 1987) [8]
Importance of Toposequence Study It is the basic concept of watershed management, because in most cases toposequence is always a part of a watershed. Integrated management of a watershed is a must not only from crop production point of view, but also checking our most valuable upper top soil from being eroded as one inch of top soil takes more than thousand years to be formed. These types of studies provide the knowledge regarding changes in different soil properties and soil forming processes along a toposequence, which can be ultimately be used for deciding different cropping system and land use plannings for different topographic positions. Variations in Soil Properties along Toposequences Many variations in different soil properties are found along toposequences which are described below. 1.
2.
Variation in Morphological Properties Along a Toposequence
Colour
Structure
Presence of mottles
Presence of concretions
Plasticity
Stickiness
Variation in soil Physical Properties Along a Toposequence
Depth of solum
Number of horizons in soil profiles
Soil textural class
Coarse fragments
Bulk density
Particle density Page | 100
3.
% porosity
Water holding capacity
Available water capacity
Variation in Soil Chemical Properties Along a Toposequence
pH
Organic carbon
Electrical conductivity
Exchangeable bases
Cation Exchange Capacity(CEC)
% Base saturation
Exchangeable Sodium Percentage (ESP)
4.
Variation in available macro nutrients (Nitrogen, phosphorus, potash, sulphur) status along a toposequence.
5.
Variation in available micro nutrients (Iron, manganese, copper, zinc) status along a toposequence.
6.
Variation in soil genesis along a toposequence.
7.
Variation in soil classification along a toposequence.
Conclusion Toposequence is the basic concept of watershed management, because toposequence in most areas a part of a watershed. Integrated management of a watershed is a must not only from crop production point of view, but also checking our most valuable upper top soil from being eroded as one inch of top soil takes more than thousand years to be formed. Drainage conditions, differential transport of eroded materials, leaching, translocation and redeposition of mobile soil constituents influence the genesis of the soils. Percentages of clay, pH, organic carbon, Cation Exchange Capacity (CEC), Percentage Base saturation and Exchangeable Sodium Percentage (ESP) has increasing trend along the slope, which could chiefly be attributed to the translocation of finer soil particles and bases down the slope through runoff and their subsequent deposition in the lower topographic positions. Physical properties of soils of low land topography are with relatively low bulk density and infiltration rate with relatively high percentage porosity and water holding capacity. Soil fertility status with respect to both macro and micronutrients were higher in low lying topographic positions which could be attributed to accumulation of higher Page | 101
amount of clay, cations and organic matter resulting from leaching and runoff from higher topographic positions as a result of intensive rain fall. Soils also vary with respect to soil genesis and classification along a toposequence. Soils vary with respect to Soil Taxonomy even at order level found in most of the transects. Hence, it is clear that toposequence or topography plays a vital and major role in soil formation. So, selection of crops, cropping-system, and land use planning and conservation measures can be planned by studying the toposequences properly. Upland soils are the sites of soil erosion with less moisture and more coarse fragments and low fertility status. So, these landforms should be used for growing plantation crops, tree crops, orchards, agroforestry, agri-hortisilviculture etc; that of medium land can be used for growing oilseeds, pulses, legumes and field crops; that of low land which are mostly characterised by impeded drainage and high water table can be used for low land paddy and pisciculture. Land use planning for upland can be diverted for buildings, construction purpose, roads and railway tracks etc.; that of medium land can be used for crop production; low lands should be avoided for construction and building purpose and low land paddy along with pisciculture can be adopted. Similarly different conservation measures can be adopted for different land types. The main conservation measures for uplands are planting vertiver and sisal (Agave sisalana) on contours and existing earthen bunds and to do silvi-horticultural plantations; that of medium land are contour cultivation, adopting cropping systems like short duration paddy/ragi/millet in kharif and pulses/groundnut/ tomato/vegetables in rabi along with lime application; that of the low land area are to take crops like rice and to prepare water harvesting tanks in between medium land and low land to collect the runoff water during rainy season and which is to be utilised for the crops at the time of need. Optimal use of land is arrived at, when land use goals are realised with minimal negative effect. This can be achieved by integrating the experience of the farming community with scientific knowledge on the soil resource. Ever since, a number of concepts have come into existence through a process of soil study, among which toposequence concept is one of them. This concept needs to be studied thoroughly well, to show its practical relationship with land use and land use planning. Study of toposequences not only helps in proper crop management to get higher crop production; but also help in proper land use planning which will ultimately help the farming
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community as well as protect earth’s two most precious natural resources ‘soil and water’. As well quoted by our former president of India late Dr. A. P. J. Abdul Kalam ‘Inspite of all the sophistications, we owe our life to the upper six inches of soil and the fact that it rains’. References 1.
Brady NC and Weil RR, Formation of soils from parent materials in The Nature and Properties of Soils 14th edn.Pearson Education Pvt. Ltd., New Delhi, 2014, 90-91.
2.
Dokuchaiev VV, Cited by Glinka KD, Dokuchaev’s ideas in the development of pedology and cognet sciences. Academy of Sciences, USSR, Pedology 1, Leningard, 1927-1990.
3.
Jenny H, Factors of soil formation, McGraw-Hill, New York, 1941.
4.
Joffe JS, the ABC of Soils, (1st Indian Edition), Oxford Book Company, Calcutta, 1965.
5.
Milne G, Some suggested units for classification and mapping, particularly for east African soils, Soil Research, 1935, 4.
6.
Sarkar D, Fundamentals and Applications of Pedology, Kalyani Publishers, Ludhiana, 2003, 30-32.
7.
FAO, Guidelines for Soil Description, FAO, Rome, 1990.
8.
Sehgal JL, Pedology Concepts and Applications, Kalyani Publishers, Ludhiana, 1996.
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Chapter - 7 Sugarcane Based Cropping System and Their Agronomic Requirements
Authors Dr. Navnit Kumar Assistant Professor-cum-Scientist, Department of Agronomy Sugarcane Research Institute, Dr. Rajendra Prasad Central Agricultural University, Bihar, Pusa, Samastipur, India Dr. Geeta Kumari Assistant Professor -cum- Scientist Department of Microbiology, Faculty of Basic Science & Humanities, Dr. Rajendra Prasad Central Agricultural University, Bihar, Pusa, Samastipur, India
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Chapter - 7 Sugarcane Based Cropping System and Their Agronomic Requirements Dr. Navnit Kumar and Dr. Geeta Kumari
Abstract Sugarcane is a long duration, widely spaced (0.80-1.20 cm) and slow growing crop up to 80-90 days takes long time for the canopy to cover the ground. It thus offers a possibility to grow an intercrops of 80-90 days to utilize the space, time, solar radiation, moisture and nutrients from upper layer of soil strata and other natural resources efficiently. Its deep root system helps to tap plant nutrients from deeper layers allowing the intercrops to feed at top layers of the soil. Sugarcane requires more irrigation during pre-monsoon period. A greater proportion of moisture is lost as evaporation from soil surface in sole sugarcane planted at wider rows. Intercrops between sugarcane rows may utilize a greater proportion of this water lost as evaporation. Intercropping also helps in reducing the weed infestation and some of the crops act as insect repellent. Though, no single crop is more remunerative than intercrops. The large un-utilized area between inter rows spaces of sugarcane cane be utilized efficiently by growing short duration intercrops. Intercropping provides considerable yield advantage over sole sugarcane owing to temporal and spatial complementarities between the components crops. Phenological characters and growth habits of sugarcane make it ideal as a components crop with most of the short duration pulses, spices, vegetables, oilseeds and even few cereals. In order to meet the growing demand of diverse crop and to arrest further decline in production and to make the sugarcane production system more viable, it is necessary to enhance the productivity of the system as a whole. Diversification in sugarcane based cropping system is necessary to get higher yield and net monetary returns, to maintain soil health, preserve environment, reduce biotic and abiotic stresses and to meet daily requirement of human and animals. The intercropping of pulses, vegetables and spices in sugarcane can provide greater yield advantage and it fits well in the cropping system. In north India, sugarcane is planted in two distinct cropping seasons. I.e. in Page | 107
autumn (October-November) and spring (February-March) at 90 cm row spacing hence intercrops of both the seasons are different. A number of crops as intercrops in sugarcane have been tested at state and national level institute for better yield and sustainability in farmer’s field. In autumn planted sugarcane, potato (Solanum tuberosum L.), wheat (Triticum aestivum L.), lentil (Lens esculenta Moench.), rajmash (Phaseolus vulgaris L.), garlic (Allium sativum L.), coriander (Coriandrum sativum L.) and nigella (Nigella sativa L.) were found most suitable intercrops. However, in spring planted sugarcane, green gram (Vigna radiata L. Wilczek.), black gram (Vigna mungo L. Hepper) and lady’s finger (Abelmoschus esculentus L. Moench) can be grown as inter crops. Recently intercropping has been recognized as potentially beneficial system of crop production. The crops like wheat and maize suppresses sugarcane, but crops like potato, garlic, rajmash, green gram, black gram, coriander, black cumin etc. do not affect the yield significantly and by better management practices it was possible to maintain higher yield levels of both the components crops. Keywords: Agronomic requirements, crop diversification, productivity, profitability, sugarcane Introduction Sugarcane (Saccharum officinarum L) is the premiere sugar crop not only of India but also all the tropical and subtropical countries of the world. It is a principal source of sugar for Indian people with a national productivity of 61.3 t/ha. There is large variability in sugarcane yield ranging from 81.0 t/ha in Tamil Nadu to 50 t/ha in Bihar (ISMA, 2018) [4]. Sugarcane being widely spaced crop with slow growth and limited lateral spread in the initial stages provides opportunity for growing short duration and high values crop as intercrop. Instead of growing sole sugarcane, intercropping of any suitable crop can be more profitable and it is a viable agronomic practice for stepping up the production, productivity and profitability of a system from a unit area during a cropping period (Kumar et al., 2015 and 2016) [6, 5]. Though, intercropping is an age old practice it has attracted world wise attention owing to yield advantage, if the crop selected are compatible (Singh et al., 2002) [16]. Intercropping not only gives extra income to the farmers but also provide money during the mid season of sugarcane for further utilization. Intercropping provides substantial yield advantage over sole crop owing to temporal and spatial complimentarity and minimizing inter or intra-specific competition (Chatterjee and Mandal, 1992) [1]. Besides there is opportunity for increasing the total land productivity, generating mid-season income and reducing cultivation cost through intercropping in sugarcane (Lal and Singh, Page | 108
2004)) [10]. Yield potential of intercropping system depends primarily on their optimum proportion of the system, area occupied by them and competitive behavior of the intercrops. To harness the benefits of sugarcane based cropping system and to sustain their yield potential, sound agrotechniques need to be standardized. This chapter provides an update on the agronomic research undertaken on sugarcane based cropping system under the diverse growing conditions in India. Temporal Diversification in Sugarcane Based Cropping System Sequential cropping is the growing of two or more crops in sequence on the same field in a year. The succeeding crop is sown after the preceding crop has been harvested. Crop intensification is only in time dimension and there is no intercrop competition. Crop sequence and crop rotation are generally used synonymously. Crop rotation is the practice of growing a series of dissimilar type of crops in the same space in sequential season to avoid the buildup of pathogens and pests at no cost that often occurs when one species is continuously cropped. Rotation of crop is not only necessary to offer a diverse diet to the soil micro flora and fauna, but as they root at different soil depths, they are capable of exploring different soil layers for nutrients. Trash shedding of sugarcane crop and their subsequent decomposition increases micronutrient availability to shallow rooted crops in next season as sugarcane absorb such nutrients from lower layers of soil. This way the rotation crop function as biological pumps by greater distinction of bio pores created by diverse roots of various sizes, forms and depths for better use of water and nutrients through the soil profile. Table 1: Sugarcane based cropping sequences Crop Sequences
Regions/State
Rice-pea-sugarcane- ratoon
Bihar
Rice/maize-sugarcane- ratoon
Bihar
Sesame/urd-sugarcane- wheat
Bihar
Rice (early)-pea-sugarcane- ratoon-wheat
Eastern U.P.
Rice (early)-sugarcane (autumn)- ratoon-green gram Eastern U.P. Rice-potato-sugarcane-ratoon-wheat
Western and Central U.P.
Rice-mustard-sugarcane-ratoon-wheat
Western and Central U.P.
Green manure-potato-sugarcane-ratoon-wheat
Western and Central U.P.
Maize-wheat-sugarcane-ratoon-wheat
Punjab, Haryana, Western U.P.
Sorghum (fodder)-berseem-sugarcane-ratoon
Punjab
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Groundnut-wheat-sugarcane-ratoon
Gujrat
Cotton-sugarcane-ratoon-sorghum
Maharashtra
Sugarcane-ratoon-wheat
Maharashtra
Rice-groundnut-sorghum-finger millet-sunhempsugarcane
Karnataka
Sugarcane-ratoon-kharif rice-winter rice-sunhemp
Andhra Pradesh
Spatial Intensification in Sugarcane Based Cropping System Spatial intensification of cropping is the need of the day to meet the requirement of 48 kg sweetner/person/year including 27 kg sugar and 21 kg gur and khandsari by 2020, India would need to provide 415 million tones of sugarcane with a recovery of 11%. Since, there is no scope for horizontal expansion of sugarcane crop for cultivation as sole crop. The only alternative left is for vertical expansion and crop diversification with less demand on space and time. Companion cropping in sugarcane in which two crop species planted within sufficient spatial proximity resulted in enhanced yield and monetary returns. Table 2: Sugarcane based remunerative intercropping system Intercropping System
Regions/State
Sugarcane + Potato
Bihar, U.P.
Sugarcane + rajmash
U.P., Uttarakhand
Sugarcane + green gram
U.P., Bihar
Sugarcane + cow pea
U.P.
Sugarcane + linseed
U.P.
Sugarcane + coriander
Bihar
Sugarcane + lentil
Bihar
Sugarcane + amaranthus
Gujrat, Maharashtra
Sugarcane + cabbage
Gujrat, Maharashtra
Sugarcane + ground nut
Maharashtra
Sugarcane + broad bean
Eastern U.P.
Sugarcane + onion
Maharashtra, Eastern U.P.
Sugarcane + garlic
Maharashtra, Eastern U.P.
Table 3: Agro-technology for sugarcane based intercrops Intercrops Rows Sowing Time Potato
2
Mid October
Seed Rate
Variety
Autumn Sugarcane 20-25 q Kufri Sinduri, K. (paired row) Chandramukhi,
Yield (q/ha) 200-250
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Wheat Lentil Rajmash
2 2 2
Garlic
2
Coriander
2
Nigella
2
Maize
1
Green gram 2 Black gram 2 Lady’s 1 finger
Mid November Mid November Mid OctoberMid November Mid October
Rajendra Alu-2 PBW-343, HD 2733 P.L. 406, Arun P.D.R.-14
40-50 kg 15-20 kg 55-60 kg 100-125 kg
Yamuna Safed, Lahsun Badsah & Local Mid October 12-15 kg Rajendra Swati, Pant Haritima Mid October 10-12 kg Rajendra Shayama & Local October 15 kg Deoki & Laxmi Spring Sugarcane February-March 15 kg P.S. 16, Sona March 15 kg T-9 February 08 kg Pusa Sawni, Prabhani Kranti
20-25 10-15 10-15 40-50
10-12 12-15 40-45 8-10 5-6 50-60
Nutrient Management Higher and sustainable sugarcane production coupled with improved quality traits needs sufficient and balanced amount of plant nutrients in soil. Dixit and Mishra (1991) [2] used recommended dose of nutrients to sugarcane and half of recommended dose to intercrops where as Gulati et al., (1995) [3] applied 100 kg P2O5, 60 kg K2O/ha as basal application and 225 kg N/ha in 3 equal splits at 30, 90 and 120 days after planting to sugarcane and recommended dose of NPK to intercrops as per sole crop. While deciding manurial schedule of the intercrop the area occupied by the crop should be considered (Singh and Lal, 2007) [17]. The fertilizers for both the crops should be supplied separately in furrows. Sundra, (1998) [23] and Singh et al., (2009) [18] opined that intercropping of pulses especially pea and lentil improved the available phosphorus and potassium content in soil at harvest of sugarcane ratoon. Sugarcane ratoon and sugar yield increased significantly with increasing levels from 120 to 180 kg N/ha. Net returns and benefit:cost ratio was also higher at higher levels of nitrogen. Saini et al., (2008) [12] reported that application of 175% of the recommended NPK produced significantly higher yield of wheat and sugarcane. Table 4: Dose and time of nitrogen application in sugarcane based intercrops Nitrogen (kg/ha)
Intercrops
Basal Application
First TopDressing
Second TopDressing
Potato
85
½
½ at earthing up
-
Wheat
50
½
¼ at first irrigation ¼ at second Page | 111
irrigation Lentil
15
Full
-
-
Rajmash
60
½
½ after first irrigation
-
Garlic
25
½
½ after first irrigation
-
Coriander
40
½
½ after first irrigation
-
Nigella
30
Full
-
-
Maize
100
1/3
1/3 -50 days after 1/3 at the time of sowing tasseling
Moong/urd 10
Full
-
-
Lady’s finger
1/3
1/3 after first irrigation
1/3 after second irrigation
60
Intercropped Grain Legumes Residue Incorporation vis-à-vis Biological Properties of Soil Suman et al., (2006) [22] found that the compatibility of legumes in sugarcane can be recognized in terms of higher microbial biomass and increased N availability. Singh et al. (2005) [15] also reported better performance of ratoon under legume intercropping systems. Table 5: Effect of intercropping on soil microbial biomass nitrogen Treatment
Soil Microbial Biomass Nitrogen (mg/kg/10 days) Before in-Situ Incorporation
After in-Situ Incorporation
Sugarcane + Cowpea
78.80
97.93
Sugarcane + green gram
78.06
83.37
Sugarcane + black gram
74.06
79.83
Sugarcane + Sesbania (Green manure) Source: Lal et al. (2002) [8]
58.56
79.09
Effect of Cropping System on Soil Physico-Chemical Properties Inclusion of short duration intercrops specially legumes in autumn and spring planted sugarcane improved the productivity, profitability and improved the soil health under plant ratoon system. Sultani et al. (2007) [21] also reported improvement in the physical properties of soil by inclusion of legumes in the system. Singh et al. (2008) [13] observed that ratoon sugarcane intercropped with lentil gave higher cane yield than that from sole sugarcane. Besides, there was improvement in the physic-chemical properties of the soil under sugarcane + lentil intercropping system with lower bulk density (1.26 Page | 112
g/cm3) and higher infiltration rate (4.75 mm/ha) compared with sole sugarcane. Table 6: Effect of intercropping system on physical and chemical properties of soil Ratoon Cane (Sole) Infiltration rate (mm/ha) Bulk density (g/cm3) Available soil N(kg/ha)
Ratoon + Berseem
Ratoon + Senji
Physical properties 3.63 4.82
4.31
1.42
1.31
1.26 0-15 cm
Initial
208.7
208.7
208.7
After harvest of forage
205.9
243.5
253.6
Initial
200.0
200.0
200.0
After harvest of forage 190.6 [14] Source: Singh et al (2007)
233.6
243.7
15-30 cm
The agricultural production systems in India are struggling for sustained growth to achieve food and nutritional security. The present system of fertilizer application is based on nutrient demand of main crop ignoring the fertilizer requirement of intercrops. However, Kumar et al., (2017) [7] obtained higher productivity and nutrient balance besides maintaining soil health with the application of 100% recommended dose of fertilizer to sugarcane and coriander with residue incorporation. Table 7: Effect of fertility levels in sugarcane + coriander intercropping system on yield and available nutrient status in post harvest soil
Treatment
Cane Yield (t/ha)
Coriander Grain Yield (t/ha) Grain Haulm
Available Nutrient Status in Post-Harvest Soil (kg/ ha) After Harvest of Sugarcane
After Harvest of Coriander
N
K
N
P
P
K
Irrigation Schedule 60 DAS
83.1
0.98
1.36
238
14.0
114
245
15.1
121
90 DAS
76.5
0.85
1.01
228
13.3
109
234
14.4
115
60, 90 DAS
88.4
1.44
2.06
243
15.2
117
253
16.1
122
S.Em. ±
1.21
0.01
0.05
3.54 0.18
1.61
1.96
0.16
1.49
CD (P= 0.05) 3.5 0.04 [7] Kumar et al. (2017) .
0.14
10
5
6
0.5
4
0.5
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Water Management Judicious use of irrigation is an important step towards sustainable sugarcane production system and therefore, thorough knowledge of efficient water management in sugarcane is of utmost importance. Any ignorance in this may result either under or over irrigation both being hazardous for crop growth and soil health. The water requirement of sugarcane varies from 200300 cm per hectare per annum. The water requirement during formative phase and grand growth phase is maximum (150 cm). In north India the water requirement of grand growth phase is met through rains, while the requirement of formative phase has to be met through irrigation. Table 8: Crop duration, water requirement and critical period of irrigation on physiological crop stages in sugarcane based cropping system S. No.
Crop
Duration Water Require (Days) Ment (cm)
Critical Stages
1
Sugarcane 300
170
Formative (60-130 DAP)
2
Wheat
100-120
35-40
C.R.I. (20-25 DAS); tillering (40-45 DAS); late jointing (70-75 DAS); flowering (90-95 DAS); dough (110115 DAS)
3
Maize
95-120
50-60
Seedling (15-20DAS); tasseling (5560 DAS); silking (75-80 DAS); Dough (90-95 DAS)
4
Green gram
65-75
25
Pre-flowering (20-25 DAS) Pod formation (35-40 DAS)
5
Black gram
80-90
20
Pre-flowering (25-30 DAS) Pod formation (50-60 DAS)
6
Rapeseed/ 100-110 Mustard
30
Pre-flowering (20-30 DAS) Pod formation (50-60 DAS)
7
Pea
130-140
15
Early growth (45 DAS) Siliqua formation (50-60 DAS)
8
Lentil
120-140
25
Early growth (40-45 DAS) Pod filling(75-80 DAS)
9
Rajmash
120-125
10
Potato
75-110
47-65
Stolon formation and tuber initiation
Under intercropping system, irrigation given to sugarcane is sufficient for intercrops also. The care should be taken, to irrigate the crop according to the need and nature of intercrops, though first irrigation should be applied after germination of sugarcane. There are several methods, viz. soil moisture determination, consumptive water use and physiological crop stages are available to decide when to apply irrigation. Among them physiological crop
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stage is the easiest to follow since no specific measurement are required and can be readily followed by farmers. Under limited water supply conditions irrigation is scheduled at moisture sensitive stages and irrigation is skipped at non-sensitive stages. Saini et al. (2008) [12] concluded that irrigation scheduled at critical growth stages of wheat crop improved growth and yield of sugarcane, apart from sustaining higher wheat yield. Table 9: Effect of irrigation schedules on yield and economics of sugarcane + garlic intercropping system Cane Yield Garlic Bulb Cane Equivalent (t/ha) Yield (t/ha) Yield (t/ha)
Treatment
Net Returns (×103 Rs/ha)
Irrigation Schedule 30 DAS
71.4
1.2
86.6
100.1
30, 60 DAS
81.3
2.6
112.4
157.5
30, 60, 90 DAS
88.0
3.4
128.9
193.3
30, 60, 90, 120 DAS
92.4
3.6
136.2
208.4
S.Em ±
1.95
0.07
2.30
3.35
CD (P= 0.05) 5.6 Kumar et al. (2016) [5].
0.2
6.6
9.5
Weed Management Sugarcane is a poor competitor with weeds due to slow initial growth upto April – May (Pre-monsoon period). Weed problems vary according to agroecological regions and management practices. Simple and valuable agrotechniques of irrigation and fertilizers are costly inputs and they go waste without having the optimum crop population in the field. There utilization has to be increased by covering the entire land area with intercrops, which in turn would also help in increasing the monetary gains of the farmers. Large number of weeds florish in sugarcane fields due to slow initial growth of the crops and wide spacing between the crop rows. Among the factors for low productivity, negligence towards weed management is the most important, as the losses due to weeds range from 40% reduction in cane yield to total crop failure (Srivastava, 2001) [20]. Table 10: Critical period of crop weed competition of some of the important sugarcane based intercrops. Crops
Critical Period of Crop Weed Competition
Sugarcane
30-120
Potato
20-40
Lentil
30-60 Page | 115
Rajmash
20-40
Wheat
30-50
Maize
15-45
Green gram
15-30
Black gram
15-30
Lady’s finger
15-30
Garlic
30-75
Rapeseed & mustard
15-40
Onion
30-75
Cauliflower
30-45
Cabbage
30-45
Pea
30-45
Linseed
20-45
To obtain higher cane yield along with intercrops, the plot must be kept weed free till the critical stage of the crop. Critical period can be defined as “the shortest period of time in the ontogeny of crop growth when weeding will result in higher economic returns”. However, intercropping suppresses weeds by its smoothering effect. High crop densities under intercropping system create severe competition to weeds and thus, reduce the weed growth to some extent. Inclusion of green gram or black gram as intercrops in spring sugarcane effectively reduces the weed population, there by decreases cost of cultivation. Under intercropping system, generally weed management is done manually by doing inter culturing operation but, in case of unavailability of labourers recommended herbicides for different intercrops may be used. Table 11: Recommended herbicides for sugarcane based cropping system Cropping System
Herbicides
Sugarcane + Potato
Pendimethalin 1.0 kg/ha or Metribuzine @ 0.35 kg/ha may be applied as pre-emergence to control important weeds.
Sugarcane + maize
Pre-emergence application of Atrazine @ 1.0 kg/ha
Sugarcane + wheat
Isoproturon @ 0.9-1.0 kg/ha after 35 days of wheat sowing.
Sugarcane + Mustard
Alachlor @ 1.5 kg/ha or pendimethalin @ 1.0 kg/ha as pre-emergence may be applied.
Sugarcane + black Pre-emergence application of Alachlor @ 2.0-2.5 kg/ha gram/green gram/cowpea or pendimethalin @ 1.0 kg/ha was found effective.
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Remunerative Sugarcane Based Intercropping System
Sugarcane + Garlic (1:2)
Sugarcane + Potato (1:2)
Sugarcane + Rajmash (1:2)
Sugarcane + Coriander (1:2)
Sugarcane + Lentil (1:2)
Sugarcane + Nigella (1:2)
Harvesting and Yield Under sugarcane based intercropping system, all of the intercrops are harvested very earlier hence there is no chance of adverse effect on sugarcane yield and sugarcane expressed its full yield potential as reported in sole crop. However, yield of intercrops depends upon its population and proportionate area occupied by them in the mixed stand. The experimental finding of Rana (2006) [11] showed that yield advantage in intercropping system vary withj crop combinations. This findings are in accordance with the results of Kumar et al. (2016) [5], who reported that autumn sugarcane + garlic with 100% recommended dose of fertilizer to both the crops recorded profitable (net return Rs 1, 96300/ha) and positive associative effect on Page | 117
sugarcane yield attributes and yield. This system also recorded significantly highest system productivity (cane equivalent yield 130.3 t/ha) with land equivalent ratio of 1.30. The positive effect of lentil intercropping on successive ratoon was reported by Lal et al (1999) [9]. Singh et al (2007) [14] opined that intercropping of berseem in winter initiated sugarcane ratoon significantly increased the number of millable canes (117.8 thousand/ha), cane yield (72.4 t/ha), cane equivalent yield (90.8 t/ha) and commercial cane sugar yield (8.81 t/ha) compared to sole cropping. Singh (2010) [19] indicated that by adopting furrow irrigated raised bed system for wheat + sugarcane showed improvement in sugarcane productivity as compared to spring and late planted sugarcane. Income of sugarcane farmer from limited land can be increased by adopting FIRB system for wheat sugarcane. Wheat + sugarcane gave more profit than the sole crop of wheat and paddy in a season. References 1.
Chatterjee AK, Mandal BK. Present trends in research on intercropping. Indian Journal of Agricultural Sciences. 1992; 62:507-518.
2.
Dixit L, Mishra A. Intercropping in sugarcane. Indian Journal of Agricultural Sciences. 1991; 36(2):261-262.
3.
Gulati JML, Mishra MM, Paul JC, Hali. Cane yield and WUE of autumn planted cane under sole and intercropping stand at different levels of irrigation. Indian Journal of Agronomy. 1995; 40(2):279-281.
4.
ISMA. Indian Sugar Mills Association. Indian Sugar. 2018; 69(4):49.
5.
Kumar N, Kumar G, Kumar A, Paswan S. Influence of manuring and irrigation scheduling on system productivity, resource use efficiency, nutrient uptake and incidence of early shoot borer (Chilo infuscatellus) in sugarcane (Saccharum spp. hybrid complex) and garlic (Allium sativum) intercropping system. Indian Journal of Agronomy. 2016; 61(3):297-306.
6.
Kumar N, Kumari G, Paswan S. Optimizing nutrient and irrigation requirement of sugarcane (Saccharum spp. hybrid complex) and French bean (Phaseolus vulgaris) intercropping system. Indian Journal of Agronomy. 2015; 60(4):524-533.
7.
Kumar Navnit, Kumari G, Kumar V. Enhancing crop productivity and soil health from intercropping coriander with autumn sugarcane through scheduling of fertilizer and irrigation. Journal of the Indian Society of Soil Science. 2017; 65(3):300-307.
8.
Lal M, Singh AK, Shahi HN. Proceedings International Symposium on Page | 118
“Food Nutrition and Economic Security through Diversification in Sugarcane Production Systems” 16-18 February, 2002, 331-337. 9.
Lal M, Singh AK, Singh M. Response of autumn sugarcane ratoon system to fertilizer - N in relation to lentil intercropping and biofertilizer. Paper presented in National Seminar on Advances in Sugarcane Technology, held during 2-3 November at IISR, Lucknow. Souvenir with Abstracts, 1999, 23p.
10. Lal M, Singh AK. Technology package for sugarcane based intercropping systems. IISR publication, Lucknow, 2004. 11. Rana DS. Effect of planting pattern and weed management on weed suppression, productivity and economics of African mustard (Brassica carinata) and Indian mustard (Brassica juncea) intercropping. Indian Journal of Agricultural Sciences. 2006; 76:98-102. 12. Saini SK, Bhatnagar A, Khetwal R. Studies on irrigation and fertilizer requirement of sugarcane and wheat crops under simultaneous planting in winter season. Proceedings of National Seminar on Varietal Planning for Improving Productivity and Sugar Recovery in Sugarcane. February, 2008, 14-15, 189-193. 13. Singh AK, Lal M, Archana S. Effect of intercropping in sugarcane on productivity of plant cane- ratoon system. Indian Journal of Agronomy. 2008; 53(2):140-141. 14. Singh AK, Lal M, Prasad SR, Srivastava TK. Productivity and profitability of winter –initiated sugarcane ratoon through intercropping of forage legume and nitrogen nutrition. Indian Journal of Agronomy. 2007; 52(3):208-211. 15. Singh AK, Lal M, Srivastava TK. Enhancing productivity and sustainability of sugarcane plant–ratoon system through planting geometry, dual- purpose legume intercropping and nitrogen nutrition. Indian Journal of Agronomy. 2005; 50(4):285-288. 16. Singh AK, Lal M, Yadav DP, Warshi AH. System approach to nutrient management in autumn sugarcane based cropping system. Second International Agronomy Congress on Balancing Food and Environment Security: A continuing Challenge, held during 26-30 November 2002 at New Delhi, Extended Summaries, Vol. I, pp 134-5. 17. Singh AK, Lal, M. Assessment of system productivity, cane physiology and economic viability of sugarcane (Saccharum complex hybrid) – based crop diversification options through on – station trials. Indian Journal of Agricultural Sciences. 2007; 77(12):866-869. Page | 119
18. Singh AK, Singh J, Singh AK, Singh SB, Sharma ML, Singh RR. Significance of pulse intercropping with sugarcane ratoon. Indian Journal of Fertilizer. 2009; 5(7):25-27. 19. Singh N. Grow sugarcane with wheat for higher return. Indian Sugar. 2010; 60(7):23-28. 20. Srivastava TK. Efficacy of certain new herbicides in spring planted sugarcane. Indian Journal of Weed Science. 2001; 35(1&2):56-58. 21. Sultani MI, Gill MA, Anwar MM, Athar M. Evaluation of soil physical properties as influenced by various green manuring legumes and phosphorus fertilization under rainfed conditions. International Journal of Environmental Science and Technology. 2007; 4(1):109-118. 22. Suman A, Lal M, Singh AK, Gaur A. Microbial biomass turnover in Indian sub-tropical soils under different sugarcane intercropping systems. Agronomy Journal. 2006; 98:698-704. 23. Sundra B. Sugarcane cultivation. Vikas Publication House Pvt. Ltd. New Delhi, 196-203.
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Chapter - 8 Smut of Pearl Millet: Current Status and Future Prospects
Authors Annie Khanna Department of Plant Pathology, CCSHAU, Hisar, Haryana, India Kushal Raj Department of Plant Pathology, CCSHAU, Hisar, Haryana, India Pooja Sangwan Department of Plant Pathology, CCSHAU, Hisar, Haryana, India
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Chapter - 8 Smut of Pearl Millet: Current Status and Future Prospects Annie Khanna, Kushal Raj and Pooja Sangwan
Abstract Smut caused by Moesziomyces penicillariae is the worldwide most destructive disease of pearl millet. The disease has been reported from different parts of the world viz., India, Pakistan, Nigeria, Ghana etc. The disease is of economic importance as grain losses upto 20 per cent were reported and the limiting factor is the cultivation of high yielding hybrids. The screening tests showed that variety ICMA 8006, ICMB 92888, ICMB 92777 and hybrids like GHB 538, GHB 719, GHB 558 etc remained resistant and can be grown in smut prone areas. The other method of disease management is the use of fungicides. Fungicides like carboxin, hexaconazole, propiconazole, carbendazim are effective in managing the disease when used as prophylactic treatment. But these days sustainable development is a major concern in agriculture so botanicals like neem, aloe vera were also used for the effective management of the disease. Keywords: pearl millet, smut, distribution, screening, resistant varieties, fungicides, botanicals. Introduction Pearl millet (Pennisetum glaucum) also known as bajra is one of the oldest cultivated crop of African and Asian countries. It is predominately a rainfed crop tolerant to drought and salinity. The crop thrives well in conditions like low rainfall and relatively poor soils. This coarse grain also known as poor man’s food has great potential for addition in food basket of the world. Pearl millet is a dual purpose crop not only its grain but fodder also of excellent quality. Pearl millet yield is prone to many biotic and abiotic constraints. Among various constraints smut, downy mildew, rust, blast and ergot are of economic importance. Moesziomyces penicillariae (Bref.) Vanky is a basidiomycetes fungus responsible for smut disease on pearl millet and belongs to the family Ustilaginaceae (Basidiomycota). It has been reported in tropical and Page | 123
subtropical zones of Africa, America and Asia (Wells et al., 1963; Thakur and King, 1988). This fungus affects the ovaries of pearl millet that are converted into sori containing dusty brown to blackish teliospores. The pathogen was earlier named as Tolyposporium penicillariae Brefeld and also known as Tolyposporium senegalense Spegazzini, or Sorosporium bullatum Schröter. According to different authors, T. penicillariae is synonymous with Tolyposporium bullatum Schröter or T. bullatus. In the year 1995, Mordue proposed that M. penicillariae and Moesziomyces bullatus are morphologically alike but has different biology. Later it was named M. penicillariae (Bref.) Vanky in 1977 and then Moesziomyces bullatus (Schröter) Vanky in 1994. Several revisions of the taxonomy of Ustilaginaceae based on morphological or molecular studies has been published in the past few years (Bauer et al., 1997; Begerow et al., 1997; Piepenbring et al., 1998; Stoll et al., 2005). Geographical Distribution Smut on pearl millet was reported in the early 1930s at Senegal by Chevalier (1931). In India, it was first reported by Ajrekar and Likhite (1933). Smut disease has been reported from different regions of the world viz., Burkina Faso, Cameroon, Gambia, Ghana, India, Malawi, Mozambique, Niger, Nigeria, Pakistan, Sierra Leone, Sudan, USA, Zambia and Zimbabwe (Peregrine and Siddiqui, 1972; Rachie and Majmudar, 1980; Rothwell, 1983). Host Range Moesziomyces penicillariae (Bref.) Vanky causing smut is known to infect Pennisetum glaucum only and no other confirmed host has been reported. Symptoms In smut of pearl millet, the infected florets and ovaries are converted into smut fungus structures called sori. Immature, green sori larger than the normal seed develop on panicles during grain filling stage. The sori appear as enlarged, oval to conical bodies projecting beyond the glumes in place of grains. Initially the sori are bright green but later they turn into brown to black coloured sori. Sori are filled with dark teliospores of the smut pathogen. The sori are usually 3-4 mm long and 2-3 mm broad at the top and covered by a thin membrane which often breaks at maturity to release brown to black coloured sporeballs. Infection involves light scattering of sori among grains on panicles till the panicle is completely covered by sori. It is observed in panicles with poor head exsertion, that the lower portion covered Page | 124
by the sheath of the flag leaf is heavily infected with smut. Yield Losses The major outbreak of this disease has proved its economic importance as a serious threat to pearl millet production in northern India, due to commercial cultivation of F1 hybrid (Thakur and King, 1988). Occurrence of smut disease on pearl millet in India was first reported in 1933 by Ajrekar and Likhite. In India, a survey during the year 1950 indicated that smut severity in farmers' fields ranged from 1 to 30% in parts of Tamil Nadu, Andhra Pradesh, and Maharashtra (Rachie and Majmudar, 1980). Bhowmik and Sundaram (1971) reported that 50-75% of the crop was infected with smut in some fields, with damage up to 100% in individual panicles. In recent years, smut has become devastating in north India, particularly in the states Haryana, Punjab, Gujarat and Rajasthan mainly due to cultivation of high-yielding hybrids based on male sterile lines. During the year 2002, grain losses due to pearl millet smut in the districts Gwalior, Bhind and Morena have been assessed as 8.87, 7.03 and 12.37 per cent, respectively (Rathore, 2004). Pathogen Characteristics The teleutospores occur in compact, ball like masses called sporeballs which vary in shape from circular to near polyhedral and measure 42325×50-175 µm in diameter. The number of teliospores aggregated in balls varies from 200 to 1400 and are yellowish-brown in colour and globose to sub-globose in shape. Teliospores germinate to produce promycelia with basidiospores and sporidia. Individual teleutospores do not separate readily and are mostly angular to round, light brown, and measure 7-12 µm in diameter. Maximum germination of teleutospores occurs at 30°C. The promycelium is four-celled and forms both lateral and terminal sporidia. Variation in germination patterns of teleutospores occurs while they are held in the sporeballs and sporidia are produced on branched hyphae in chains. The fungus readily forms colonies on media containing extracts of pearl millet, maize or sorghum grain, and also grows well on potato or carrot agar at 30-35°C. Colonies growing on agar media are composed of budding sporidia that are spindle-shaped, single-celled and hyaline, and vary in length from 8 to 25 µm. Frequency of germination of teleutospores is low, and isolated, single teleutospores are seldom seen to germinate. Pathogen Life Cycle The source of primary inoculum is sporeballs in the soil from the previous infected crop and surface contaminated seed used for sowing. Page | 125
Teleutospores germinate following rain showers and produce numerous airborne sporidia that infect the pearl millet crop at flowering. Two sporidia of compatible mating types are required to form a dikaryotic infection hypha. Infection occurs through young emerging stigma and is prevented or reduced by rapid pollination (Bhatt 1946). The latent period (i.e. time from inoculation to spore production) is about 2 weeks and sori mature within 3-4 weeks. Matured sori rupture to release masses of sporeballs which under favorable condition germinate to produce a second cycle of sporidia. These sporidia can infect late planted crops in nearby fields or panicles of late tillers in the same field, and the cycle is repeated. Moesziomyces penicillariae is not internally seedborne, but typically soil and air borne disease. Teleutospores remain viable in soil at depths up to 22.5 cm for about 1 year (AICMIP 1961). Epidemiology Smut of pearl millet is a floral disease and its infection is confined to individual spikelets, often scattered to near base of the earhead. Airborne inoculums of M. penicillariae infects pearl millet florets directly at time of flowering. In the field, infected florets are converted into sori, which break at maturity and release brown to black spore balls and healthy seeds get surface contaminated. These surface contaminated seeds when used for sowing, act as the primary source of inoculum. Seed may be infested with teliospore balls, but infection does not take place through seedlings (Bhatt 1946). In the field, teliospores in soil or crop residues or adhering to seed, also serve as primary inoculum. Teliospores viable in the soil may produce basidiospores and sporidia (Patel et al., 1959). The secondary spread of the disease is through the teleutospores. Teleutospores are both air and soil borne. They germinate to produce sporidia which become airborne and cause infection through young emerging stigma. Smut sori larger than the normal grain become visible two weeks after infection. High relative humidity (>80%) and an average temperature of 300C favour disease development. Secondary spread of the disease within a crop is minimal because of a prolonged latent period of two weeks by which flowering is almost complete. Pollination prevents infection by the smut pathogen (Thakur et al., 1983a). A late flowering crop can be infected by the inoculums from the infected crop in an adjacent field but the infection intensity depends upon weather conditions, wind direction and the susceptibility level of the cultivar.
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Diagrammatic Representation of Infection Cycle Screening Techniques Screening for smut resistance was initiated in the early 1960’s in India, but no lines with consistently high levels of resistance were identified. A systematic effort to develop a field-based screening technique was developed under AICPMIP and an effective resistance screening technique was developed which is being used to screen genetic resource accessions and breeding lines. Many lines with high levels of resistance (1- 5% smut infected florets in the panicle
3
>5- 10% smut infected florets in the panicle
4
>10- 20% smut infected florets in the panicle
5
>20- 35% smut infected florets in the panicle
6
>35- 50% smut infected florets in the panicle
7
>50- 75% smut infected florets in the panicle
8
>75- 90% smut infected florets in the panicle
Fig 1: Pearl millet smut severity scale
The smut disease incidence under the AICPMIP program is scored generally by counting the number of diseased plants and the lines are categorized as follows: lines with 0-5% smut incidence are highly resistant, lines with 5.1-10% smut incidence are resistant, lines with 10.1-25% smut incidence are susceptible and lines above 25% smut incidence is considered highly susceptible. Page | 128
Host Resistance Growing disease resistant cultivars is the most economical and feasible method of disease control. In India screening for smut resistance was initiated in the early 1960, but no line with consistently high level of resistance was identified. However, work with the world collection of Pennisetum spp, suggest that accessions from Mali, Nigeria, Senegal and Zimbabwe have some degree of smut resistance (Murty et al., 1967). Sources of smut resistance have been identified in gene bank accessions from Cameron, India, Lebnon, Mali, Nigeria and Togo representing diverse agro ecological zones (Thakur et al., 1986, Thakur et al., 1992; Thakur and King, 1983b). Following pedigree breeding and artificial screening of progenies of crosses involving smut resistant lines, a large number of agronomically diverse smut resistance lines were identified. Smut resistant hybrids currently available are GHB 538, GHB 719, GHB 558, PUSA 23, RHB 121, PB 106, ICMH 356, GHB 757, GHB 744, GHB 732, HHB 197, PUSA 266, ICTP 8203, CZP 9802, ICMV 155, B 2301, SABURI, SHARDHA, RAJ 171, PUSA 383, JBV 2 and ICMV 221. Other smut resistant lines available are ICMA 88006, ICMB 92888, ICMB 92777, IP 19874, MH 1317, ICMPS 100-5-1, ICMPS 900-9-3, ICMPS 1600-2-4 and ICMPS 2000-5-2. Based on the screening of the entries, the new hybrids are promoted from time to time for cultivation and this process continue in future depending upon the new race/ mutant of pathogen. Fungicides and Botanicals for the Management of Smut Disease Since smut is strictly soil and air borne disease therefore management by seed dressing fungicides is not possible. Several protective and systemic fungicides are applied to protect ear head of the crop from infection. Pearlmillet it is a high tillering crop, therefore use of fungicides as spray has major economical limitation for the farmer. Thiram (Dashora and Kumar, 2009) carbendazim, copper oxychloride hexaconazole, propiconazole (Meena et al., 2012) are effective fungicides for the management of smut. Ridomil at higher concentration is also effective in manging the disease but according to some researchers even carboxin is the most effective one. With changing trend, advancement and development towards sustainable agriculture botanicals are gaining importance in crop protection in view of their selective properties, low cost and safety to ecosystem. Many botanicals have been identified to be effective in the control of plant Page | 129
diseases. In case of botanicals leaf extract of jamun and eucalyptus, gel of aloe vera, oil or neem seed kernel extract has been found effective in the management of the disease. References 1.
Ajrekar SL, Likhite VN. Observations on Tolyposporium penicillariae Bref. (The bajri smut fungus). Current Science. 1933; 1:215.
2.
Anonymous. All India Coordinated Millet Improvement Project, 1961.
3.
Bauer R, Oberwinkler F, Vánky K. Ultrastructural markers and systematics in smut fungi and allied taxa. Canadian Journal of Botany. 1997; 75:1273-1314.
4.
Begerow D, Bauer R, Oberwinkler F. Phylogenetic studies on nuclear large subunit ribosomal DNA sequences of smut fungi and related taxa. Canadian Journal of Botany. 1997; 75(12):2045-2056.
5.
Bhatt RS. Studies in the Ustilaginales. 1. The mode of infection of the bajra plant (Pennisetum typhoides Stapf. & Hubbard) by the smut, Tolyposporium penicillariae Bref. Journal of the Indian Botanical Society. 1946; 25:163-186.
6.
Bhowmik TP, Sundaram NV. Control of pearl millet smut with systemic fungicides. Plant Disease Reporter. 1971; 55:87-88.
7.
Chevalier A. Une maladie du penicillaire au Senegal. Revue de Botanique Appliquee. 1931; 11:49-50.
8.
Dashora K, Kumar, A. In vitro evaluation of relative effectiveness of some fungicides against smut (Tolyposporium penicillariae) Disease of pearl millet. National Bureau of Plant Genetic Resources, New Delhi. Pestology. 2009; 33(4):45-47.
9.
Meena RL, Mathur AC, Majumdar VL. Management of pearl millet smut through cultural practices and fungicides. Indian Phytopathology. 2012; 65(3): 268-271.
10. Mordue JEM. Moesziomyces bullatus. IMI Descriptions of Fungi and Bacteria no. 1245. Mycopathologia. 1995; 131:49-50. 11. Murty BR, Upadhyay MK, Manchanda PL. Classification and cataloguing of world collection of genetic stocks of Pennisetum. Indian Journal of Genetics and Plant Breeding. 1967; 27:313-394. 12. Peregrine WJH, Siddiqui MA. A revised and annotated list of plant diseases in Malawi. CAB Phytopathology Paper. 1972; 16:29. Page | 130
13. Piepenbring M, Bauer R, Oberwinkler F. Teliospores of smut fungi: Teliospore connections, appendages, and germ pores studied by electron microscopy; phylogenetic discussion of characteristics of teliospores. Protoplasma. 1998; 204:202-218. 14. Rachie KO, Majmudar JV. Pearl millet. University Park, Philadelphia, USA: Pennsylvania University Press. 1980, 307. 15. Rathore RS. Studies on smut of pearl millet with special reference to its management. Ph.D. thesis, Jiwaji University, Gwalior (M.P.), 2004, 5185. 16. Rothwell A. A revised list of plant diseases occurring in Zimbabwe. Kirkia. 1983; 12(ll):275 17. Stoll M, Begerow D, Oberwinkler F. Molecular phylogeny of Ustilago, Sporisorium, and related taxa based on combined analyses of rDNA sequences. Mycological Research. 2005; 109(3):342-356. 18. Thakur RP, King SB. Smut disease of pearl millet. ICRISAT. Information bulletin no 25. International Crops Research Institute for the Semi- Arid Tropics Patancheru, A. P. 502 324, India, 1988, 17. 19. Thakur RP, King SB, Rai KN, Rao VP. Identification and utilization of smut resistance in pearl millet. Research Bulletin. No.16, ICRISAT, India, 1992. 20. Thakur RP, Subba Rao KV, Williams RJ. Effects of pollination on smut development in pearl millet. Plant Pathology. 1983a; 32:141-144. 21. Thakur RP, Subba Rao KV, Williams RJ. Evaluation of a new field screening technique for smut resistance in pearl millet. Phytopathology. 1983b; 73:1255-1258. 22. Thakur RP, Subba Rao KV, Williams RJ, Gupta SC, Thakur DP, Nafade SD et al. Identification of stable resistance to smut in pearl millet. Plant Disease. 1986; 70:38-41. 23. Wells HD, Burton GW, Ourecky DK. Tolyposporium smut, a new disease on pearl millet, Pennisetum glaucum, in the United States. Plant Disease Reporter. 1963; 47(1):16-19.
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Chapter - 9 Decision Support Systems and Crop Simulation Models for Effective Nutrient Management
Authors D. Raja Ph.D. (Agri) Scholar, Department of Soil Science and Agricultural Chemistry, College of Agriculture, UAS, Raichur, Karnataka, India Y. Balachandra Soil Scientist, KVK, Vizianagaram, Andhra Pradesh, India
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Chapter - 9 Decision Support Systems and Crop Simulation Models for Effective Nutrient Management D. Raja and Y. Balachandra
Introduction Nutrient management plays very important role in enhancing the yield, productivity as well as economy of the crops and cropping systems. Management of plant nutrition includes through understanding of the nutrient needs of the crop in question as well as the nature and the source of plant nutrient apart from its interaction with the type of soil as well as the prevailing environment and management practices followed for the crop. Among the different plant nutrients required by the plants major research is conducted on major nutrients like Nitrogen, Phosphorus and Potassium. Through understanding of the dynamics as well as requirement by the crops and their interaction in the soil and prevailing environment has led to the development of several decision tools to manage nutrients. This paper presents and discusses the utility of such decision tools as well as simulation models in managing the nutrients effectively without causing any detrimental effect on the environment. Further the utility of these tools under Indian conditions were also discussed at the end. Before presenting the details of the decision support systems and crops simulation models one should understand the following definitions as well as meaning of the following terms. Decision: Management option to decide whether to apply or not to apply any inputs for efficient crop production. Support: Any rule helps to take effective decision. System: Holistic term means having the components arranged to explain the processes involved as well as the interaction with desired output. Tools: Any helping aid to take correct decisions may be decision rules, crop growth stages, nutrient uptake curves or software. Model: Representation of the real system in an understandable manner. MAY be a schematic diagram; lay out plan of a house, description of the complex processes in the form of sketches etc. Page | 135
Forms of Model: There may be four forms of model depending on its way of describing a system. These are: 1.
Conceptual or verbal: if a system is described in natural language.
2.
Diagrammatic: if the description of the system is done by graphics, e.g. “box and arrow” diagram of carbon cycle.
3.
Physical: if the system is described by a real physical mock-up in a small scale, e.g., a tinker-toy model of a watershed.
4.
Formal or Mathematical: if a system is described by mathematical formulation (usually using algebraic or differential equations). A mathematical model is called analytical when the solution of the equations is obtained by purely mathematical argument(s). A mathematical model whose solution is obtained by numerical approximation usually involving computers is called simulation model.
Steps of Modeling Process (Datta, 2008) Modeling process can be broadly divided into four steps: 1.
Formulation: Qualitative diagram and then quantitative mathematical formulations are constructed on the basis of qualitative hypothesis and objective.
2.
Verification: This step includes selection of method of solving differential equations, viz. analytical or by numerical method using a computer, choice of algorithm, selection of methods for the same algorithm, writing computer programme and its verification.
3.
Calibration: In this step the numerical values for the initial conditions and constants in the equations are specified. The basic problem involved is parameter estimation.
4.
This may require specific laboratory or field experiment by curve fitting wherein the model is run repeatedly using different parameter values and compared to the same dynamic data set until a satisfactory fit is obtained. This, sometimes, is called as fine tuning of the model.
5.
Analysis and Evaluation: This step comprises. a) Model Validation: It is defined as model analysis concerned with evaluating model quality relative to the real world using comparisons with empirical data. b) Model Quality in Complete Sense Includes: i) its usefulness for system control or management, ii) understanding or insight Page | 136
provided, iii) accuracy or prediction, iv) simplicity or elegance, v) generality and vi) robustness (insensitivity to assumptions). c)
Analysis of Uncertainty: This includes i) parameter sensitivity and ii) error analysis.
d) Analysis of Model Behavior: This includes analysis of the model with respect to its stability. Simulation: Imitation of the real processes on real term basis with the help of some equations or cycles or rate reactions etc. During earlier days several mathematical equation were developed by well-known scientists to explain the growth of plants, dry matter accumulation in plats as well as different plant parts, nutrient release patterns during incubation, nutrient uptake patters. These equations were off late being used for developing effective tools in the form of software’s or decision support systems. Decision support systems mean many things to different people and the expression has become common in the decision-science field (Sprague, 1975; Jones, 1998). Decision support systems will represent diverse computerbased programs ranging from simple spreadsheets to complex simulation models. Some of the important decision tools for nutrient management and their utility are mentioned in following table. Table: List of nutrient management decision tools and their utility. S. No. Decision Tool 1
Manage-N
2
Amaize-N
3
NuDSS
4
Nutrient Expert
5
QUEFTS
6
Adapt-N
7
Expert-N
Utility Response of crops to Nitrogen, nitrogen requirement, recommendation and environmental impact. Forecasting crop yield and N-fertilizer requirements, and planning N-fertilizer and irrigation applications for sitespecific maize crops Nitrogen recommendation for Maize Software for Irrigated Rice Nutrient management as well as tool for SSNM for Rice Software for formulation of fertilizer recommendations as well as SSNM tool for Maize and Rice Nutrient management for Rice and Wheat as well as SSNM tool for Rice and Wheat Nitrogen management for Maize and assessing the environmental fate of applied nitrogen Nitrogen management for Wheat and annual crops
The major benefits of using the decision support systems or software for nutrient management are as follows: Major Benefits 1.
Optimum use of costly fertilizers and lot of savings on the money spent on fertilizers. Page | 137
2.
Maximum production of crops with reasonable economic returns per every rupee spent on fertilizers.
3.
Matching the fertilizer application in accordance with the crop needs resulting in reduction in the loss of fertilizers.
4.
Reducing the use of fertilizers depending upon the soil fertility as well as crop needs.
5.
Great reduction in the environmental pollution caused by excess use of fertilizers especially the nitrogen.
6.
Better economics as well as enhanced fertilizer use efficiency.
7.
Tool for recording the initiatives followed in place on farm to decrease nitrogen leaching and phosphorus runoff to ground water.
8.
Estimate the off-farm impacts of nitrogen and phosphorus on water quality and provide suggested mitigation strategies e.g. by changing form, rate or timing of nitrogen or phosphorus application or other mitigations such as nitrification inhibitors if appropriate.
9.
Provide a permanent record of the information and process followed to develop the nutrient management actions of the farm.
10. Provide proof for any outside organization that have instigated best management practice with respect to nutrients on the farm. Generally any decision support tool will contain prediction tool, correction tool as well as management tool. Usually the prediction tool predicts the deficiency in the system and the correction tool inform the users about the corrective measures to be taken to correct the system deficiencies and the management tool decides the economics of the corrective measures. An example of nutrient prediction tool based on Stanford equation is given below. Calculations of N needs can be estimated from an adaptation of the Stanford equation (Stanford, 1973): Nfert = (Yld x NYld) - [Nsoil + (Ngm x Cgm) + (Nm x Cm)]/E Where: N fert = Predicted N fertilizer requirement (kg N/ha). Yld = Dry matter yield, vegetative and reproductive (kg/ha). NYld = Mean concentration of N in vegetative and reproductive tissues (%N/100). Page | 138
Nsoil = Nitrogen from soil organic matter and previous crop residue mineralization and from soil atmospheric deposition during growing season (kg N/ha). Ngm = Nitrogen mineralized from green manure in current growing season (%N/100). Cgm = Proportion of N mineralized from green manure that is absorbed by plant (0-1). Nm = Nitrogen mineralized from manure (kg N/ha). Cm = Proportion of N mineralized from manure that plant absorbs (0-1). E = Fertilizer efficiency (0-1). In the case of P, requirement can be predicted based on the following simple equation. Pfert = (bc-b0/a2) x depth/10 x placement factor. Where: Pfert = Amount of P fertilizer (kg P/ha). bc= Target critical level in the soil (mg P/kg). b0= Measured level of extractable P in the soil (5 cm depth is recommended) (mg P/kg). a2= Buffer coefficient (the extractable P increase per unit applied P) (mg P/kg)/ (kg P/ha). In the case of K, a combination of the N and P methods can be used for predicting the K requirements. Just begin by estimating how much fertilizer K is needed to raise the soil K level (K0) to the critical soil K level (Kc), also based as in the case with P on a “buffer coefficient”. In addition, the amount of K that is likely to be removed or taken up by the plant biomass is estimated and the amount of K fertilizer needed to provide that quantity of K is estimated and divided by the appropriate efficiency factor of K fertilizer uptake and utilization. The equation of K is as follows. Kfert = (Kc-K0)/Kbc x depth/10 x placement factor + Kuptake/Keff Where: Kfert = Amount of K fertilizer (kg K/ha). Kc= Target critical level in the soil (mg K/kg). K0= Measured level of extractable K in the soil (5 cm depth is recommended) (mg K/kg). Page | 139
K uptake= Amount of K absorption (kg K/ha). Keff = Efficiency factor for K fertilizer absorption and utilization, fraction (0-1). Crop Models and Efficient Nutrient Management Crop simulation models were originally developed to forecast the crop growth and the final yield and productivity. Later, as the understanding of the crop processes as well as the interaction of crops with the surrounding environmental factors and the response to the applied inputs like water and nutrient has led the scientific community to develop several crop models for various purposes. Off late all most all the crop models were linked with the simulation models which were developed to explain the nutrient flows as well as nutrient uptake and release patterns. To name a few famous CERES and CROPGRO models were linked to CENTURY model to understand the response of applied organic residues and the fertilizers to the crops in terms of nutrient turn over as well as amount of carbon sequestered in the soil apart from predicting the environmental fate of applied fertilizers. Models play an important role in optimizing fertilizer use in agriculture to maintain sustainable crop production and to minimize the risk to the environment. It is a common feature that agro-ecosystems, like many other ecosystems, receive excessive applications of nitrogen (Schlesinger et al., 2006). This has caused nitrate pollution to surface water (Schlesinger et al., 2006), to groundwater via leaching through soils, and contributed to the rise in N emissions. Imbalance in N supply relative to crop demand can also compromise growth and quality of produce. Therefore, it is important to develop effective systems to optimize fertilizer-N application in agricultural systems to maintain sustainable crop production and to minimize the risk to the environment. The optimum levels of fertilizer-N are controlled by various dynamic factors such as the weather, soil conditions and the N demand for plant growth. It is generally impossible to obtain reliable estimates of optimum N levels by conventional statistical interpretation of a programme of field trials. Attempts have been made to use the knowledge of fundamental processes governing availability and acquisition of nutrient-N in the soil-plant system to devise mechanistic models for various crop species (Jarvis, 1995; Hoogenboom et al., 1999; Brisson et al., 2003; Jones et al., 2003). An example of the model schematic diagram is given in Fig.1. The most prominent individual nutrient response models that cover a range of crops are the EPIC models (Sharpley Page | 140
and Williams, 1990a, b) and the DSSAT models (Hoogenboom et al., 1999; Jones et al., 2003). EPIC uses a single group of algorithms for simulating more than 20 crops, with each crop having its own unique parameter values. Versions of the model have been used widely to simulate soil-N dynamics on a large scale by many researchers (Huffman et al., 2001). The DSSAT group of models, on the other hand, focused more on the physiological development of crops, dealing specifically with potential yields and their dependence on the environment. The models used different routines for the various crop types. This group of models includes CERES (Jones and Kiniry, 1986 ;) for cereals, CROPGRO (Boote et al., 1998) for grain legumes, and SUBSTOR (Ritchie et al., 1995) for root and tuber crops. In all, they cover more than 16 different crops and most have been successfully evaluated in different climatic zones (Huffman et al., 2001). The EPIC and DSSAT models have been used in both basic and applied research to study the effects of climate and management on growth and yield. However, these models are generally species dependent, and therefore different models are required for different crops to study N response on yield, causing difficulties in the application of model to devise environmentally friendly and sustainable fertilization strategies. Moreover, the required inputs of these models are generally difficult to obtain and the models can be difficult to run due to their complexity. References 1.
Boote KJ, Jones JW, Hoogenboom G. Simulation of crop growth: CROPGRO model. In: Peart RM, Curry RB. (Eds.), Agricultural Systems Modeling and Simulation. New York: Marcel Dekker, 1998, 651-691.
2.
Brisson N, Gary C, Justes E, Roche D, Zimmer D, Sierra J et al. An overview of the crop model STICS. Eur. J Agron. 2003; 18:309-332.
3.
Datta SC. Theory and Principles of Simulation Modeling in Soil-Plant System, Capital Publishing Company, New Delhi, 2008, 3.
4.
Hoogenboom G, Wilkens PW, Tsuji GY. (Eds), Decision support system for agrotechnology transfer (DSSAT) version 3. Honolulu HI: University of Hawaii, 1999, 4.
5.
Huffman EC, Yang JH, Gameda S, de Jong R. Using simulation and budget models to scale-up nitrogen leaching from field to region in Canada. The Scientific World 1, 2001, 699-706.
6.
Jarvis NJ. Simulation of soil water dynamics and herbicides persistence in silt loam soil using the MACRO model. Ecol. Model. 1995; 8:97-109. Page | 141
7.
Jones CA, Kiniry JR. Ceres-N Maize: A simulation model of maize growth and development. Texas A & M University Press, Collage Station, 1986.
8.
Jones JW, Tsuji GY, Hoogenboom G, Hunt LA, Thornton PK, Wilkens PW et al. Decision Support System for agrotechnology transfer, DSSAT v3. In Tsuji GY, Thornton PK (eds.) Understanding Options for Agricultural Production. Kluwer Academic Publishers, Dordrecht/Boston/London, 1998.
9.
Jones JW, Hoogenboom G, Porter CH, Boote KJ, Batchelor WD, Hunt LA et al. The DSSAT cropping system model. Eur. J Agron. 2003; 18:235-265.
10. Jungkunst HF, Freibauer A, Neufeldt H, Bareth G. Nitrous oxide emissions from agricultural land use in Germany-a synthesis of available annual field data. J Plant Nutr. Soil Sci. 2006; 169:341-351. 11. Neeteson JJ, Carton OT. The environmental impact of Nitrogen in Field Vegetable Production. Acta Hort. 2001; 563:21-28. 12. Ritchie JT, Griffin TS, Johnson BS. SUBSTOR: Functional model of potato growth, development, and yield. In: Modelling and Parameterization of the Soil-Plant-Atmosphere System: A Comparison of Potato Growth Models, 1995, 401-434. 13. Schlesinger WH, Reckhow KH, Bernhardt ES. Global Change: The nitrogen cycle and rivers. Water Resour. Res. 2006; 42:W03S06. 14. Sharpley AN, Williams JR. EPIC-erosion/productivity impact calculator: model documentation. US Department of Agriculture. Technical Bulletin No. 1768, 1990a, 235. 15. Sharpley AN, Williams JR. EPIC-erosion/productivity impact calculator: user manual. US Department of Agriculture, Technical Bulletin No.1768, 1990b, 127. 16. Sprague RH. Conceptual foundations for decision support systems, 1975. 17. Stanford G. Reviews and analysis. Rationale for optimum nitrogen fertilization in corn production. J Environ. Qual. 1973; 2:159-166. 18. Williams JR, Jones CA, Dyke PT. The Epic model. In: Sharpley AN, Williams JR. (Eds.), Epic-Erosion Productivity Impact Calculator. 1. Model documentation. U S Department of Agriculture Technical Bulletin No 1768. USDA: Washington DC. 1993, 92.
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Chapter - 10 On-the go Sensors for Recommendation of Fertilizers for Field Crops in Different AgroEcological Regions
Authors D. Raja Ph.D. (Agri) Scholar, Department of Soil Science and Agricultural Chemistry, College of Agriculture, UAS, Raichur, Karnataka, India Y. Balachandra Soil Scientist, KVK, Vizianagaram, Andhra Pradesh, India
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Chapter - 10 On-the go Sensors for Recommendation of Fertilizers for Field Crops in Different Agro-Ecological Regions D. Raja and Y. Balachandra
1.
Introduction
The advanced nutrient management is the science of using advanced, innovative cutting edge site specific technologies to manage spatial and temporal variability in inherent nutrient supply from soil to enhance productivity efficiency and profitability of agricultural production systems. It requires understanding of the spatial variability in soils. The fields and even sub field often vary in soil fertility and productivity. Studies have highlighted the benefits of precision nutrient management in reducing the nutrient losses. Baker et al. (2005) reported reduced off site transport of agricultural chemicals via surface runoff, subsurface drainage and leaching when precision agriculture practices were followed. Generally soil properties vary greatly across space and time. The spatial availability of nutrients in soil under agricultural systems is the integrated effect of chemical, physical and biological properties of soil. The soil variability can occur on any scale including area, field and regions within the field and even between few millimeters spacing (Bouma and Finke, 1993). Conventionally the spatial and temporal variability of nutrients in soil is assessed based on a rigorous field sampling followed by soil testing, both of which involve time and energy. At present, development of gadgets like chlorophyll meters, leaf colour chart and optical sensors provide alternatives for drawing instant nutrient management decisions. Recent advances indicate that the need based nutrient management in crop fields can be ensured through geospatial technologies such as global positioning system (GPS), geographical information system (GIS), remote sensing, real time and variable rate applications (VRA) (Varinderpal-Singh et al., 2010). The most widely and indiscriminately used nutrient in crop production is nitrogen. The dynamics of nitrogen supply to plants governs the content of chlorophyll in plants and thus spectral properties of plant leave scan be used as an index to coin precision nitrogen management strategies. As the Page | 145
plant demand for nutrients other than N cannot be easily accessed from the spectral properties of the leaved other techniques are being employed for making precision employed for making precision nutrient management decisions while corresponding spatial and temporal variability in nutrient supply from the inherent sources. Therefore, there is a need to relook in to our traditional method of fertilizer recommendation. The various decision support tools introduced into farm production of late aim at precise and need based fertilizer recommendation. In the past various aspects of fertilizer recommendation techniques were deliberated thoroughly by number of reviewers (Alam, 2005; Alam, et al., 2006; Biradar et al, 2005, 2012, 2012a; Bijay-Singh et al., 2012, Costa et al., 2001, and Harmandeep et al., 2010). Nevertheless, the comprehensive coverage of different decision support tools is still very meager, and hence this effort. 2.
Optical Sensors
A wide range of optical sensors are available and classified as multi spectral and hyper spectral sensors. A multi spectral sensor such as CropCircle (450-880 nm) and CropScan (440-11750 nm) has wide spectral resolution with a limited number of wavebands used to describe nitrogen (Robert et al., 2009), biomass variation and leaf area index (Darvishzadeh et al., 2006) while hyperspectral sensors such as ASD Field Spec have fine spectral resolution with continuous wavebands across the electromagnetic spectrum which provides detailed biophysical and biochemical information. Optical sensors measure visible and near infrared (NIR) spectral response from plant canopies to detect the N stress) Penuelas et al., 1994; Ma et al., 1996). Chlorophyll contained in the palisade layer of the leaf controls much of the visible light (400-720 nm)NIR electromagnetic spectrum (720-1300 nm) depends on structure of mesophyll tissues, spectral vegetation index calculated as the normalized difference vegetation index (NDVI) calculated as (FNIR-Fred)/FNIR + Fred), where FNIR and Fred are respectively the fractions of emitted NIR and red radiation reflected back from the sensed area provide information about photosynthetic efficiency, productivity potential and potential and potential yield. 2.1 a) Green Seeker The Green Seeker (GS) canopy sensor (Trimble, USA) is a commercially available and widely used active optical sensor that emits res (650 nm) and NIR (770 nm) wavebands. The sensor has viewing angle and a field of view which ranges from 52 to 145 cm2. Optimal height range for sensing with the Page | 146
unit is between 71 and 112 cm. Measured spectral reflectance is expressed as spectral vegetation indices such as NDVI. The NDVI has been shown to provide an appraisal of photosynthetic efficiency productivity potential and potential yield (Raun et al. 2001; Bronson et al., 2011). The sensor has been used in various crops such as wheat (Heege et al., 2008; Bijay-Singh et al., 2013), rice (Bijay-Singh et al., 2015), barley (Soderstron et al., 2010), corn (Tremblay et al., 2009), sugarcane (Singh et al., 2006, Portz et al., 2012) and cotton (Raper et al., 2013).
Using Green Seeker optical sensor, Bijay-Singh et al., (2011) collected data from experiments conducted at Karnal Modipuram and Ludhiana and observed robust relationship between in-season Green Seeker optical sensor based estimates of yield at Feekes 5-6 and 7-8 growth stages and actual wheat yields. The amount of additional N fertilizer required was determined by taking the difference in estimated N uptake between estimate of yield potential with no added fertilizer N and with fertilizer N application. 2.1 b) Yara N-Sensor It is a passive multispectral scanner consisting of two diode array spectrometers measuring light reflectance at specific wave bands related to crops chlorophyll content and biomass. Two fibre optic inputs are located on each end of the sensor unit for viewing both left and right of the sensing platform and both ends feed into one spectrometer. The field view for each crop sensing fibre optic input is 12 o. The sensor is tractor mounted and measures the crops light reflectance covering approximately 50 m2 of crop area. The sensor determines the crop N status and accordingly adjusts the N fertilizer rates (Raper et al., 2013; Raper and Varco, 2015). The sensor is able to capture the crop variability with high spatial resolution and performs large number of readings per unit time. Soil sensor can be used for analyzing soil properties such as pH, electrical conductivity, salinity, dissolved oxygen and nutrient concentration, which are subsequently turned into georeferenced maps to facilitate site specific nutrient application. Page | 147
Electro chemical sensors are capable of assessing spatial variability of different soil chemical properties directly or indirectly. Soil fertility is usually measured using either an ion selective electrode or an ion-selective field effect transistor. Ion selective membranes are also available to measure NO3-N. However reports are not reliable in assessing N supplying capacity of soil. Whereas electrical and electromagnetic sensor technology uses various measurement systems based on electrical circuits to determine the ability of soil media to conduct or accumulate electrical charge. Optical sensing technology uses visible and infrared wavelength ranges to rapidly quantify soil properties. It is the interaction between incident light and soil surface properties such that the reflected light varies as a function of soil physical and chemical properties. These are having high potential for estimation of soil organic carbon content based on soil colour (Adamchuk et al., 2004). 2.1 c) Crop Circle The Crop Circle active crop canopy sensor provides classic vegetative index data as well as basic reflectance information from plant canopies and soil. Unlike passive radiometric light sensors, the Crop Circle is not limited by ambient lighting conditions. Measurements can be made day or night due to its unique, light source technology. For on-the-go applications, the Crop Circle sensor can be mounted to virtually any type of vehicle to remotely sense and/or map plant or crop canopy biomass while driving through a field. The compact size and low weight design allows Crop Circle to be easily adapted to pole-mounted and handheld applications. Information produced by the sensor can be utilized to quantify the impact of nutrients, water, disease or other growing conditions on plants or crops. It incorporates three optical measurement channels. The sensor simultaneously measures crop /soil reflectance at 670 nm, 730 nm and 780 nm. A unique feature of the sensor, unlike any other active sensor on the market, is its ability to make height independent spectral reflectance measurements. Holland Scientific refers to these reflectance measurements as Pseudo Solar Reflectance (PSR). This means the spectral reflectance bands are scaled as percentages and will not vary with sensor height above a target. This opens the possibility of using literally dozens of vegetative indices that do not use ratio based calculations. Data can be easily and quickly recorded to a text file Page | 148
on an SD flash card. Additionally, by connecting a GPS receiver to the Geo SCOUT, data collected from the sensor can be geo-referenced and stored for later analysis in third party GIS software. 2.1 d) Crop Scan Every substance emits, absorbs, transmits or reflects electromagnetic radiation in a manner characteristic of the substance. This is the underlying principle involved in all remote sensing. By measuring the quantity of radiation in each of the wavelengths, the characteristics of the substances can be defined. In practice, only certain selected wavelength bands need to be chosen to discriminate between selected characteristics of substances. For the CROPSCAN radiometer system, narrow band interference filters are used to select certain bands in the visible and near infrared (NIR) regions of the electromagnetic spectrum. This region is useful for quantifying the reflectivity of canopies as affected by stresses of various kinds. The NIR bands of 750-900 nm are particularly useful for detecting and estimating the severity of foliar disease of plants. Longer wavelengths in the NIR may be useful for estimating biochemical content of plants. 2.2 Chlorophyll Meters 2.2 a) Fixed Threshold Value Approach Need based nitrogenous fertilizers are applied whenever chlorophyll meter reading is less that the pre-set threshold value. The threshold value which represents the limit below which a reduction in yield occurs must be pre-established. Fertilizer-N applications are necessary below this threshold value to avoid yield loss. The SPAD values of the index leaf are monitored at 7-10 days interval starting from 15 days after transplanting till initiation of flowering. In-season top dressing of 30 kg N ha-1 was recommended whenever SPAD value falls below the critical value of 35 for rice in Philippines. The use of critical SPAD 35 reading resulted in similar yields with less fertilizer-N and higher agronomic efficiency compared to fix split timing applications (Peng et al., 1996). The threshold value is not universal and may vary in different rice growing environments like wet and dry seasons. 2.2 b) Sufficiency Index Value Approach Sufficiency index is defined as the SPAD value of the test plot expressed as percentage of the SPAD value of an over fertilized reference plot. Fertilizer Page | 149
N is applied as and when sufficiency index value falls below a set value. This approach has the benefit of being self-adjusting for spatial, temporal and varietal variations as SPAD threshold values are established with respect to an over fertilized plot. The fertilizer N was top dressed at the rate of 30 kg N ha1 whenever sufficiency index was less than 90% up to 50% flowering. BijaySingh et al. (2006) followed the criteria of 90% sufficiency index in direct seeded rice.
Fig 1: Relationship between SPAD readings and total dry matter production in sweet corn during 2011-14 and 2015-16.
The approach saved 50 kg N ha-1 fertilizer N in comparison to blanket application of 120 kg N ha-1 with no reduction on the grain yield. The fixed and dynamic sufficiency index approaches for need based fertilizer N management technologies were compared with farmers practice, local recommendations, soil test crop response correlation based recommendations or urea briquette deep placement method at on-farm locations in South Asia. The use of 32 to 65 kg N ha-1 less fertilizer produced grain yield equivalent to soil test based recommendations and higher agronomic efficiency. Table 1: Chlorophyll meter (SPAD) threshold values for N application reported by different scientists in various crops across the world S. No.
Crop
SPAD Threshold value
Place Philippines
Source
1
Rice
35
2
Wet DSR
32 and 29
Peng et al. (1996)
3
Wheat
42
Punjab
Bijay-Singh et al. (2002)
4
Rice
37.5
Pakistan
Hussain et al. (2003)
5
Rice
35
Bangladesh
Kyaw et al. (2003)
6
Wheat
42
Pakistan
Hussain et al. (2003)
7
Rice
37
Huan et al. (2002)
Maiti et al. (2004)
Page | 150
3.
8
Wheat
44
Bangladesh
Kyaw (2003)
IGP, India
Maiti and Das (2006)
9
Wheat
37
10
Wheat
50-52
11
Maize
50
China
12
Rice
36
Bihar
Ghosh et al. (2013)
13
Corn
50
Karnataka
Vikram et al. (2015)
14
Sweet corn
50
Karnataka
Mallikarjun Swamy et al. (2016)
Takebe et al. (2006) Jian-hua et al. (2008)
Leaf Colour Chart
3.1 Real Time N Management The LCC score of the first fully expanded leaf is monitored at 7-10 days interval starting from 15 days after sowing/transplanting till initiation of flowering/tasseling and prescribed amount of fertilizer-N is applied whenever the colour of leaves falls below the critical LCC score. The local guidelines on the use of LCC have now been available for the major crops in Asia. The LCC shade 4 has been found to be the threshold score for transplanted rice in IGP. For various crops and regions the threshold values is listed in table 2. 3.2 Fixed-Time Variable Rate Approach International Rice Research Institute (IRRI), the Philippines, considered leaf as ultimate indicator of soil supply and plant uptake has come out with a simple, farmer friendly and inexpensive LCC, a hand held plastic strip, that can be used as a complementary decision making tool to determine the need for N application in field periodically. LCC has been used successfully to guide fertilizer N application in rice, wheat and maize (Bijay-Singh et al., 2002; Yadvinder Singh et al., 2007; Varinderpal-Singh et al., 2010, 2011) Sugarcane (Chandrashekar, 2010).
Page | 151
Fig 1: Relationship between LCC thresholds on total dry matter production of sweet corn at MARS, Raichur karnataka during 2014-15 and 2015-16.
The chart contains seven shades of green from yellowish green (No. 1) to dark green (No. 7) and is calibrated with the SPAD meter is a comprehensive and decisive apparatus that takes into account soil supply, crop uptake and plant health. It helps achieve need based variable rate of N application to crops based on soil N supply and crop demand. It is an ideal and an eco-friendly tool to optimize N use, irrespective of the source of N; native soil N, applied fertilizer source etc. The LCC being cost effective and advantageous over the tedious, time consuming and costly leaf sampling, or laboratory analysis and consequent delayed recommendation, needs large scale adoption. Leaf greenness is closely related to photosynthesis rate and biomass production, and is a sensitive indicator of changes in crop N demand during the growing season. Critical or threshold value of the LCC is, therefore, defined as the intensity of green color that must be maintained in the uppermost fully opened leaf of the crop plant and at critical/predetermined stage of crop a calibrated dose of fertilizer N needs to be applied whenever leaf greenness is below the critical LCC threshold. Thus, maintaining the leaf greenness just above the LCC critical value ensures high yields with needbased N applications thereby leading to high fertilizer N use efficiency. Farmers will benefit hugely if they can adjust N application through LCC as an indicator of actual crop condition and nutrient requirement (VarinderpalSingh et al., 2011). The leaf colour chart that was originally developed for rice was found handy in other cereals/grasses such as maize, wheat, sugarcane etc. (BijaySingh et al., 2002; Yadvinder-Singh et al., 2007; Varinderpal-Singh et al., 2010, 2011). Witt et al. (2005) reported its suitability in maize as indicated by Page | 152
spectral reflectance measurements performed on rice and maize leaves. They calibrated LCC values with the chlorophyll meter to fix the critical colour shade for local maize cultivar groups and crop conditions. Hawkins et al. (2007) stressed the need to consider relationship between measured N stress and optimum N rate required while making N rate decisions. Nitrogen stress determined with chlorophyll meter would help to reduce variation and improve the calibration of N stress with the nitrogen rate difference from the economic optimum nitrogen rate (EONR). Farmers can use the LCC to qualitatively assess foliar N status and adjust N top dressing. The thresholds have to be calibrated to specific soil, climatic, and crop conditions (Witt et al., 2005). Under practical on-farm situations, LCC proved to be as good as the chlorophyll meter in terms of high yield and improved N use efficiency. Its simplicity and cost effectiveness makes it superior over the latter. Now, recommendations are available and the chlorophyll meter and leaf colour chart are used currently in Asia for N management in rice and wheat (Singh et al., 2002). Alam et al. (2005), Bijay-Singh et al. (2002) and Shukla et al. (2004) proved that the current recommendation of three split applications for rice at specified growth stages is not adequate to synchronize N supply with crop N demand. Many researchers identified a critical LCC value of 4 is ideal than LCC 5 for need-based N management in transplanted rice (Yadvinder-Singh et al., 2007; Budhar, 2005). In Southern Karnataka, Kenchaiah et al. (2000) reported that N recommendation based on LCC 4 produced significantly higher grain yield over blanket and farmers’ practice. Further, agronomic efficiency of nitrogen was higher due to higher grain yield with lesser N application with LCC besides saving of 10-20 kg N/ha. Biradar et al. (2005) while studying comparative advantage of LCC opined that recommended dose of nitrogen was inadequate in achieving higher yields of irrigated rice in the TBP area whereas, economics indicated a higher benefit-cost ratio for LCC-5 than with RDN. However, in rainfed rice in Tamil Nadu, application of N fertilizers in splits @ 20 kg/ha at LCC threshold 3 was more beneficial in enhancing the growth and yield (Jayanthi et al., 2007). Yadvinder et al. (2007) suggests that LCC-based N management assures optimal rice yields consistent with efficient N use and enhanced farmers’ profits due to saving in the use of N fertilizers. A basal application of N @ 20 kg/ha though increased the growth parameters, it was not reflected in yields. But when LCC based N was supplied up to panicle initiation stage it enhanced Page | 153
yield. These findings highlight need for location specific research to develop recommendation for rice cultivars. Avijit et al. (2011) reported that higher agronomic efficiency of N with consistent high grain yield could be regarded as an indicator for efficient N management in rice. On the basis of higher grain yield along with corresponding higher agronomic and recovery efficiency and other parameters LCC < 5 was found optimum threshold. Alireza and Anthony (2011) reported considerable opportunity to increase yield and N use efficiency (NUE) levels through improved N management using LCC in rice. The LCC threshold 4 with 25 kg N/ha and critical LCC value of 4 with 35 kg N/ha were found to be suitable for guiding N application to achieve the highest grain yield in Amol region of Northern Iran. Combination of LCC and chlorophyll meter based N management strategies resulted in optimum rice grain yield and high N use efficiency with less fertilizer N application than the blanket recommendation (Bijay-Singh et al., 2012). Similar to rice, N management in maize through leaf colour chart was useful to avoid lower fertilizer application besides applying at appropriate time so as to increase the productivity and profitability. Shukla et al. (2004) and Alam et al. (2005) reported that N applied based on crop need as determined by LCC was more efficient. Top dressing with 30 kg N/ha per dressing and maintaining the leaf greenness up to LCC-5 recorded higher grain yield of maize as compared to LCC-4 , LCC-3 and N@20 and 10 kg/ha per top dressing (Sarnaik, 2010). Further, Biradar et al. (2012) observed that applying the right dose of N (240 and 150 kg/ha in maize and wheat), coupled with the right time of application (i.e. 3-split applications) using LCC-based real time N management was beneficial in increasing the yield and profitability of maizewheat system among farmers of northern Karnataka. Roland et al. (2013) reported that the LCC5 recorded higher grain yield of maize as compared to LCC 4 and 3. Shukla et al. (2004) and Alam et al. (2005) also confirmed that N applied based on crop need as determined by LCC was used more efficiently. Table 2: LCC threshold value for N application reported by different scientists in various crops across the world S. No.
Crop
LCC Threshold Value
Place
Source
1
Rice
4.0
IGP, India
Bijay-Singh et al. (2002)
2
Rice
3.5
Bangladesh
Kyaw et al. (2003)
Page | 154
3
4.
Rice
5.0
Maiti et al. (2004)
4
Rice
4.0
Punjab
Budhar (2005)
5
Wheat
4.5
Bangladesh
Alam et al. (2006)
6
DSR
3.0
Punjab
Bijay- Singh et al. (2006)
7
Scented rice
2.0
Philippines
Fairhurst et al. (2007)
8
Aromatic rice
3.5
Philippines
Fairhurst et al. (2007)
9
DSR
3.0
Tamilnadu
Jayanthi et al. (2007)
10
DSR
4.0
Tamilnadu
Nachimuthu et al. (2007)
11
Rice
4.0
Ludhiana
Thind et al. (2007)
12
Rainfed rice
3.0
Tamilnadu
Jayanthi et al. (2007)
13
Maize
5.0
Punjab
Sarnaik (2010)
14
Maize
5.0
Punjab
Varinderpal-Singh et al. (2011)
15
Maize
4.0
N-Iran
Alizera et al. (2011)
16
Rice
5.0
17
Maize
5.0
18
Sweet corn
5.0
19
Corn
5.0
Roland et al. (2013)
20
Maize
5.0
Mathukia et al.(2014)
21
Corn
5
Karnataka
22
Sweet corn
5
Karnataka Mallikarjun Swamy et al. (2016)
Avijit et al. (2011) Punjab
Singh et al. (2011) Datturam and Shashidhar (2012)
Vikram et al. (2015)
Modeling Approach
These are computer based decision support tools for precise nutrient management in tune with crop demand, native soil contribution. The models ae designed to consider spatial and temporal variability in nutrient supply and ensure need based nutrient applications. Nutrient Expert Nutrient expert (NE) developed by International Plant nutrient expert (IPNI), USA based on SSNM principles for the purpose of precise quantity of fertilizers in maize. Later it has been standardized for wheat, rice and cotton. It developed farmers’ specific fertilizer recommendation based on 3-5 years previous yield, organic and inorganic fertilizers applied attainable yield, soil fertility indicators, residue content and growing environment. It considers availability of resources to estimate their yield target. On-farm trials conducted in Haryana and Punjab NE based strategies increased grain and biomass yield by 14 and 9% respectively over farmers practice and 5 and 3% respectively over state recommendations (Varinderpal-Singh et al., 2016). Page | 155
Banerjee et al. (2014) conducted field experiments to evaluate NE based fertilizer recommendation. It was found that NE recommendation gave highest yield, agronomicefficiency, physiological efficiency and recovery efficiency over state recommendation and farmers practice. Field experiment conducted at ARS, Siruguppa on validation of nutrient expert at 8 and 10 t ha-1 yield targets. It was indicated that yield improvement in maize by adoption of NE based fertilizer recommendation as compared to state recommendation and farmers practice (Vikram et al., 2016). Nutrient expert based nutrient management in maize produced 14.7 % higher yield over soil test based recommendation (Kumar et al., 2015). Sapkota et al. (2014) reported that wheat production with NE-based recommendation supplemented with Green Seeker guided nutrient management under no tillage system can be carbon neutral. This combination of tillage and nutrient management strategy can be recommended for wheat production in Northwest Indo gangetic plain to increase yield, efficiency and profitability as well as to reduce agriculture’s contribution to climate change. QUEFTS Model A empirical model Quantitative Evaluation of Fertility of Tropical Soils (QUEFTS) to predict the effect of fertilizer application on yield, basis of soil and plant characteristics(Witt and Dobermann, 2002). It has four steps potential indigenous nutrient supply, nutrient uptake, yield range in tune with nutrient uptake, estimation of final yield. It also take into consider interaction of nutrients to achieve optimal nutrient balance. Table 3: Fresh cob yield with husk and fresh cob yield without husk, green fodder yield, stover yield and harvest index Dry Fresh Cob Green Fodder Yield Without Fodder Yield Yield Husk (t ha-1) (t ha-1) (t ha-1)
Treatment
Fresh Cob Yield With Husk (t ha-1)
Harvest Index (%)
LCC threshold 4
13.26
7.93
16.23
8.14
45.1
LCC threshold 5
15.21
8.13
19.03
9.01
44.4
SPAD threshold 40
12.48
7.81
16.72
7.62
42.8
SPAD threshold 50
13.62
8.95
17.27
7.878
44.0
NDVI 0.6
11.84
6.17
16.12
7.57
42.1 Page | 156
NDVI 0.8
14.4
8.15
18.33
8.88
44.0
No
4.21
1.38
7.53
3.85
35.7
C.D. (p=0.05)
1.73
1.41
2.24
1.08
5.9
(Mallikarjun Swamy et al., 2016) Table 4: Grain and straw yield maize as influenced fertilizer recommendation by decision support tools Treatment
Grain Yield Stover Yield (kg ha-1) (kg ha-1)
Nutrient Expert based target 8 t ha-1 (NE8)
7186
9178
Nutrient Expert based target 10 t ha-1 (NE10)
7998
9539
SPAD threshold 40 (SPAD 40)
5501
9755
SPAD threshold 50 (SPAD 50)
6782
8927
LCC threshold 4 (LCC 4)
6867
10150
LCC threshold 5 (LCC 5)
7664
9711
Recommended dose of fertilizers (RDF)
6121
8367
Farmers practice (187.5:107.5:150 kg NPK ha-1)
6463
9383
N0
3059
5488
732
1692
C.D. at 5% Source: Vikram et al. (2015)
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