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Effect of shading and plant density on growth, yield and oil composition of clary sage (Salvia sclarea L.) in north western Himalaya a
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Rakesh Kumar , Saurabh Sharma & Vijaylata Pathania
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Natural Plant Products Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
To cite this article: Rakesh Kumar , Saurabh Sharma & Vijaylata Pathania (2013): Effect of shading and plant density on growth, yield and oil composition of clary sage (Salvia sclarea L.) in north western Himalaya, Journal of Essential Oil Research, 25:1, 23-32 To link to this article: http://dx.doi.org/10.1080/10412905.2012.742467
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The Journal of Essential Oil Research, 2013 Vol. 25, No. 1, 23–32, http://dx.doi.org/10.1080/10412905.2012.742467
Effect of shading and plant density on growth, yield and oil composition of clary sage (Salvia sclarea L.) in north western Himalaya Rakesh Kumar*, Saurabh Sharma and Vijaylata Pathania Natural Plant Products Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176 061, India
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(Received 20 January 2012; final form 7 August 2012) The experiments were commenced in January 2009 and repeated in 2010 at the CSIR-Institute of Himalayan Bioresource Technology (Council of Scientific and Industrial Research), Palampur, India to investigate the effect of shading and plant density on plant growth, yield, volatile oil content and composition in clary sage. Four levels of shade (0, 25%, 50%, 75% shade) and three planting geometry levels (30 30 cm, 45 30 cm, 45 45 cm) were tested as per split plot design. Plants grown in full sunlight (control) produced significantly higher number of leaves than heavy shading (75% shade). Plant spread, root length, number of roots/plant, flower weight/plant, total biomass/plant, oil content and oil yield significantly reduced with increase in shade levels. Flower yield (q/ha) was significantly higher when the crop was planted under narrow spacing 30 30 cm compared with 45 30 cm and 45 45 cm spacing levels. Oil content and oil yield were not affected by different spacing levels. Linalyl acetate and sclareol were higher under 25% shade, germacrene D required 50% shade, but linalool was better in open environment. Keywords: Salvia sclarea; clary sage; irradiance; essential oil; linalool; linalyl acetate
Introduction Clary sage (Salvia sclarea L.), a xerophytic biennial plant (family Lamiaceae) is native to Southern Europe. It is cultivated worldwide, especially in the Mediterranean region and Central Europe. The whole plant, mostly the inflorescences, possesses a very strong aromatic scent and its essential oil used for the flavor and fragrance industries, where it is used as flavoring agent, in food and liqueur preparations, in perfumery formulations and for cosmetic purposes (1). Different components of S. sclarea essential oil have diverse biological activities that allow for the many medicinal and pharmaceutical applications of the plant materials and/or extracts. Its oil has antifungal (2), antimicrobial (3) and antioxidant properties (4). Among the major components of the oil, linalool is known for its antibacterial and acaricidal properties, and germacrene D for its pheromone activity (5, 6). Many physiological processes in plants are affected by irradiance, which is one of the most important environmental factors affecting plant survival, growth, reproduction and distribution (7, 8). The amount of light reaching inside the canopy and absorbed by the plant changes with plant density. Yield reduction by shading will depends upon crop species as well as the degree of shading. Shading occurs mainly due to dense plant population, intercropping, planting geometry and excessive vegetative growth, which affects the crop *Corresponding author. Email:
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performance through reducing photosynthetic capacity of plant (9). Light is a key factor in the ultimate production of many compounds because it supplies the energy needed to fix carbon. Most of the plant responses to shading are lower dry matter production, photosynthetic retention in the stem at the expense of root growth, longer spear development and bigger and thinner leaves. However, the effects of different light intensities caused by different plant densities have not been determined for clary sage. Essential oil yield is strictly related to the studied genus of the medicinal plant physiological aspects, which are influenced by environmental factors; among these, solar radiation is one of the most relevant factors (10). Environmental factors, e.g. photoperiod, radiation and temperature have strong influence on plant development and the relation between biomass production and essential oil is related to higher radiation and photosynthetic rates of plants (11). Plant spacing is an important factor in determining the microenvironment of the crop. The chemical composition of the essential oil from clary sage is almost exclusively determined by the geographical habitat of the plant, whether wild or cultivated (12–15). Studies on essential oil yield conditioned by shade levels have shown that each species responds differently to light intensity, such as Thymus vulgaris (16) and Matricaria chamomilla (17), with increased essential oil yield when grown under intense
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R. Kumar et al.
light. Anethum graveolens (18), Salvia officinalis (16) and Pothomorphe umbellata plants gave higher essential oil yield when cultivated under shade. The highest essential oil yield of P. umbellata (L.) Miquel was observed in the second harvest and plants under 30% shade (10). No evidence in the literature on the S. sclarea grown with shade has been presented. The purpose of the present study was to investigate the effect of shading and plant density on yield and oil production dynamics in S. sclarea.
keeping the sensor inverted at 1 m above the canopy at different growth stages. With the PMR-4, rates of photosynthesis, transpiration and stomatal conductance were recorded during noon hours at different growth stages in the field. Leaf area was measured by portable laser leaf area meter. Chlorophyll concentration index (CCI) was measured by a CCM 200 (Opti-Sciences, Tyngsboro, MA, USA). The data was analyzed by software SYSTAT-12 of Systat Software Inc. (Chicago, IL, USA) and treatments were tested at a 5% level of significance to interpret the significant findings.
Experimental
Planting of the crop Good-quality well decomposed farmyard manure (FYM) @ 15 t/ha was incorporated into the soil before transplanting, every year. A common fertilizer dose of @ 90:50:50 kg NPK/ha was applied to supplement the nutritional demand of the crop. These were applied before crop transplanting in the form of single super phosphate (P2O5: 16%) and muriate of potash (K2O: 60%). Nitrogen was applied in three equal splits through urea (N: 46%); one third dose before transplanting and remaining two-thirds was applied in equal does at one month after transplanting and at maximum vegetative stage. Hand weeding was done three times at monthly intervals.
Experimental site During 2009 and 2010, field experiments were conducted at the research farm of Institute of Himalayan Bioresource Technology (CSIR), Palampur, India (1325 m amsl, 32°06′N longitude, 76°33′E latitude). The soil of the experimental field was clayey in texture, acidic in reaction (pH 6.1), high in organic carbon (1.0%), low in available N (150.5 kg/ha), high in available P (21.2 kg/ha) and available K (534.2 kg/ha). Experimental details Good-quality seeds of CIM Chandni variety of clary sage were brought from Central Institute of Medicinal and Aromatic Plants, Lucknow (UP), India during November 2008. A nursery crop of S. sclarea was raised during 15 January 2009 and 4 January 2010 in sand beds through seeds. Two-month-old seedlings were transplanted in the field. Four shading levels, namely 0% shade (control or full sunlight), 25%, 50% and 75% shade were the main plot treatments, and three planting geometry levels, namely 30 30 cm, 45 30 cm and 45 45 cm were the sub-plot treatments. A sub-plot of 4.05 2.50 m size contained 104, 72 and 45 plants with 30 30 cm, 45 30 cm, 45 45 cm spacing levels, respectively. The experiment was replicated three times. Plants grown in open condition (non-shade frame) were considered controls. Shade treatments were imposed using green shading nets of 25%, 50% and 75% above the wooden frames and fixed at a height of 3 m above the ground to provide 75%, 50% and 25% reduction in light. Green agro shade nets with standard size of 3 m width and 50 m length with 25%, 50% and 75% shade were used. This was made with high-density polyethylene (HDPE) plastics. Similar cultural practices were followed for both the agro shade net house and open fields. Light intensities at noon were measured with a LI-190 quantum sensor of (LI-COR Inc. Lincoln, NE, USA). In addition, mid-day photosynthetically active radiation (PAR) was also measured with a PMR-4 steady state porometer (PP Systems, Herts, UK) at top and bottom of the canopy. The reflected radiation was obtained by
Growth and yield analysis Biometric observations were recorded at monthly interval and at harvest. Five plants/plot were selected for recording plant height, plant spread, number of branches/plant and number of leaves/plant. Plant height was measured from the ground level to tip of the top leaf. Plant spread was recorded in north–south and east–west directions. Five plants from the second row were uprooted and were partitioned to leaf, stem, root and flower. Data on phenological stages, namely bud initiation, 50% budding, 100% budding, flower initiation, 50% flowering and 100% flowering, were collected. The plants were irrigated throughout the cropping season to maintain vigorous growth. Whenever a treatment plot had attained 100% flowering, the crop was harvested manually with secateurs and biometric observations were recorded. Essential oil extraction From open and shade treatment, 1 kg fresh flowers of S. sclarea were separated and hydrodistilled for 6 hours in Clevenger-type apparatus giving transparent light yellow oil. The essential oil was decanted and dried by anhydrous sodium sulfate (Merck). It was stored in a dark glass bottle at 4°C before to gas chromatography– mass spectrometry (GC–MS) analysis. Oil content was reported at v/w basis. The oil productivity (kg/ha) was calculated by multiplying the oil content with specific
The Journal of Essential Oil Research gravity of oil (0.9) and the biomass yield of the respective treatments. Gas chromatography analysis
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GC analysis was carried out on a Shimadzu GC-2010 gas chromatograph with flame ionization detector (FID) and a DB-5 capillary column. The operating condition were as follows: carrier gas hydrogen, with a flow rate of 2 mL/minute, the oven temperature was programmed as follows: 70°C (4 minutes) and then 70–220°C at 4°C/minute, injector and detector temperatures were set at 220°C. Gas chromatography–mass spectrometry GC–MS analysis was carried out by a QP2010 (Shimadzu, Tokyo, Japan) equipped with an AOC5000 Auto injector and DB-5 capillary column (SGE International, Ringwood, Australia) of 30 m length, 0.25 mm i.d. and 0.25 μm film thickness. Temperature was programmed from 70° to 220°C at 4°C/minute, held isothermally at 70°C and 220°C for 4 and 5 minutes, respectively. MS source temperature, 200°C; interface temperature, 220°C; injector temperature, 220°C. Sample injection volume 2 μL (dilution: 10 μL oil in 2 mL dichloromethane, GC grade); split ratio 1:50 and mass scan 50–600 amu. Helium was used as a carrier gas with 1.1 mL/minute flow rate. Identification of components The retention index was calculated for all volatile constituents using homologous series of n-alkanes (C8–C24). The components of oil were identified by matching their mass spectra with those stored in the computer library, namely Wiley, New York mass spectral (MS) library, National Institute of Standards and Technology (NIST) (19) and their retention indices (RI). Results Growth and development During both years, a similar trend was obtained for growth data. So the results have been pooled for two years. The shade net used in this experiment manipulated the micro-climatic parameters that influenced crop growth. The influence of irradiance on dry matter accumulation in different plant parts was evident throughout this study (Figure 1), although in early stages of growth plant height was more under open conditions but in later stages the plant’s grown under intense shade (50% and 75%) produced taller plants (Figure 1). In all the shade levels, the number of leaves/plant increased up to 120 days after planting (DAT) but declined thereafter. The number of leaves/plant was significantly higher in open sun condition and decreased with decreasing
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irradiance level. Likewise, the plant spread in N–S and E–W directions increased up to 120 DAT in all the shade levels. The plant spread in both directions was higher in open sun conditions than other shade levels, but at harvest it was higher under 50% shade levels. Fresh flower weight/plant, total fresh biomass, root length and number of roots/plant were significantly higher under open light conditions than at 25%, 50% and 75% shade levels. However, CCI content was not affected by different shade levels. Plant height, plant spread and number of leaves varied with spacing levels (Figure 1). Salvia sclarea plants spaced at 45 45 cm recorded higher plant height and number of leaves/plant than other spacing levels. Plant spread increased up to 120 DAT but was not affected by different spacing levels. A perusal of data presented in Table 1 showed that root length and number of roots/plant were not affected by different spacing levels. However, CCI, fresh flower weight/plant and total fresh biomass/plant were significantly higher at wider plant spacing (45 45 cm) compared with other spacing levels. Phenological parameters Days taken to different phenological stages of S. sclarea delayed with increase in shade level (Table 2). Crop planted under 75% shade took a significantly higher number of days for different phenological stages followed by 50%, 25% shade and control throughout the growth period. The planting geometry could not affect bud initiation, 50% and 100% budding, and 100% flowering; 100% flowering is the important stage for the harvest of the crop. The effect of plant spacing on different phenological stages of the crop was not significant (Table 2). Leaf area index increased up to 50% shade level and declined thereafter, but the effect of shade level was not significant (Table 3). Clary sage planted in 30 30 cm recorded significantly higher leaf area index. Crop planted at 45 30 cm in 25% shade level recorded significantly higher leaf area index but remained on a par with crop planted in 30 30 cm, irrespective of shade level and 45 30 cm at 50% shade levels, but recorded significantly higher leaf area index than crop planted under 45 45 cm. Gas exchange Stomatal conductance and photosynthetic rate in clary sage grown under different shade levels decreased with decreasing light intensities (Table 4). Crop planted under open conditions at 45 45 cm spacing recorded significantly higher stomatal conductance. The photosynthetic rate decreased with increasing shade levels. The rate of photosynthesis reduced significantly when the plants were planted under different shade levels.
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R. Kumar et al. 0%
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Days after transplanting Figure 1. Effect of shade levels and plant geometry on growth of clary sage.
Yield attributes and yield Data presented in Table 5 reveals that different shade levels could not bring significant effect on inflorescence length and number of spikelets/plant. However, fresh flower yield/plant (g) was significantly higher
under open sun conditions and consequently flower yield (q/ha) was significantly higher under control (no shade). The crop planted in open sun conditions remained on a par with the crop planted in 25% and 50% shade, but recorded significantly higher flower
The Journal of Essential Oil Research Table 1.
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Effect of shade levels and plant geometry on yield attributes of clary sage.
Treatment Shade levels (%) 0 25 50 75 LSD (p
