Hereditas 135: 211-215 (2001)
Production of low input and stress tolerant wheat germplasm through the use of biodiversity residing in the wild relatives SHAFQAT FAROOQ and FAROOQ-E-AZAM Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan Farooq, S. and Azam, F. 2001. Production of low input and stress tolerant wheat germplasm through the use of biodiversity residing in the wild relatives. -Hereditas 135: 21 1-215. Lund, Sweden. ISSN 0018-0661. Agricultural biodiversity adds value to crop, induces resistance, contributes enormously to human foodstuff, removes fear of genetic uniformity and ensure food security of the world. For these reasons, NIAB initiated a programme on collection, evaluation, and utilisation of agro-biodiversity related with wheat and wheat wild relatives. The focus of the programme was on the addition of stress tolerance from wild species to cultivated wheat. The objectives were i) to have a permanent source of stress tolerant germplasm, ii) to facilitate availability of such germplasm for environment friendly, profitable and sustainable agriculture on stressed lands and iii) to ensure safety of biodiversity (through gene conservation) for the stability of future agriculture. During 1998-2001, we tested wheat lines developed by using biodiversity residing in the Aegilops species. The material was tested in an area that required stress tolerant germplasm. Planting was done in fields where cotton was already growing up to the stage of second picking. The inputs included only half the amount of recommended dose of fertiliser, approximately half of the normal irrigation, no herbicide and two applications of compost. Two of the lines tested in these trials out-yielded all existing wheat cultivars traditionally grown in this area and convinced the farmers that biodiversity does play a role in adding value to the existing material, making it suitable for specific requirement. This paper describes, in detail, the significance of the plant material for the area, practical achievements, acceptance by the farmers and economic feasibility of the stress tolerant material developed at NIAB.
S. Farooq, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan. E-mail:
[email protected]
Crop genetic diversity adapted to a particular environment determines the requirement of fertilisers, pesticides and irrigation for that very climate. The farmer communities not relying on locally acclimatised varieties lose the control of the farming system and become dependent on the outside resources of seed and the other required inputs. Hence not only the food security will go into the hands of those providing resources but the local crop diversity: a vital source for long-term sustainability in agricultural and self reliance and global food security will be lost. Even in the present era of biotechnology and genetic engineering, about 60 % of the world’s agricultural land, mostly in the marginal areas (COOPER 1993) is still farmed by traditional farmers who meet all their food need from these lands (BERG 1995). Since the green revolution, varieties perform best under rain-fed and irrigated conditions, and thus the marginal area and less hospitable farming environments are not suitable for these varieties (BERG 1996). Self reliance in food production in most such areas, therefore, depends on adapting technologies and germplasm developed for a wide range of poor production environments through the use of diversity adapted to that area which otherwise would be eroded if not properly managed and utilised. Pakistan is blessed with a wealth of genetic diversity in wild and cultivated plants (ANONYMOUS 1999). It is thus imperative that the diversity native
to this country that has been collected should be evaluated and utilised in crop improvement programme in order to strengthen the basis for sustainable agricultural production especially on saline stressed lands. However, working with salinity is a difficult task and requires multidisciplinary approaches depending upon i) the gravity of the situation, ii) priorities of the agricultural sector, iii) resources of the country and iv) social acceptance of the approach in terms of economic benefits. Pakistan has about 6.8 million hectares of salt affected land (GASSEMI et al. 1995) and the country’s first priority in the agricultural sector is to achieve a wheat production target of 26.433 million tones by 2010 through a growth rate of 2.93 % per annum (ANONYMOUS 2000). There are 4.1 million small farmers possessing 5-10 hectares of land that is being degraded at a high rate due to salinity and drought (FAROOQ2001). Presently, water availability is 30 YO less than that in 1999-2000 and is further diminishing. The farmers want to see their lands productive with minimum possible inputs but without sacrificing food and social security of their families. To cope with some of these problems, a multidisciplinary research programme is underway (ANONYMOUS 1997) through which genetic diversity for salt tolerance was to be identified and/or evolved for its possible integration into existing breeding system. The objective was to identify, evaluate or tailor
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Hereditas 135 (2001)
low input varieties of wheat for cultivation on saline/ stressed land in order to provide a source of germplasm that would remain continuously available to cope with any stress situation as and when required. MATERIAL AND METHODS Collection of germplasm
NIAB has identified a range of biodiversity native to saline lands that includes wild plants, land races, grasses (FAROOQet al. 1995) and wild relatives of wheat (FAROOQet al. 1988, 1989). Among them, Aegilops species were preferred for use in wheat improvement programme because Aegilops cylindrica, Ae. tauschii and Ae. geniculata are a part of the biodiversity available in Pakistan especially in the province of Baluchistan. The species possess considerable tolerance to salinity and drought (FAROOQ and AZAM 2001). The most promising among these were accessions of Ae. cylindrica and Ae. geniculata (FAROOQ1990). Ae. cylindrica is especially characterised by profuse tillering, a character that can be exploited for crop improvement (FAROOQ2001). It was anticipated that after the addition of valuable gene(s) from Aegilops species, commercial cultivars be made stress tolerant and widely adaptable and would thus give better performance on saline soils compared to the existing and available salt tolerant germplasm (FAROOQet al. 1992). Development and testing of germplasm
The germplasm was initially screened for salinity tolerance (FAROOQet al. 1988, 1989). The identified tolerance was then transferred to hexaploid wheat cultivars LU-26 and Pak-81 (FAROOQet al. 1992). LU-26 is marginally tolerant to salinity with excellent grain weight and quality while Pak-81 is a very high yielding and widely adaptable cultivar. Both are now badly susceptible to rust and are no more under commercial cultivation. Performance of the material under stressed and normal conditions was tested in collaboration with the private sector (FAROOQ2001). For this purpose, we selected cotton fields in the south of the province of Punjab where annual rainfall is less than 250 mm (ANONYMOUS 2000). The planting was made in the month of November on raised beds (SAYREand MORENORAMOS1997) in the field with a standing cotton crop. Pre-soaked seeds (60 kg ha ') were spread on the beds. Furrows were flooded with water to provide moisture. Twenty days after seed germination, 800- 1200 kg ha compost, along with one bag of urea ha I , was applied, and a second application was made after removal of the cotton
sticks in January. No chemical method of weed control was adopted due to controlled moisture on the beds. Weeds that only grew in the furrows were removed manually. Non stressed testing was conducted in collaboration with Cotton Research Station, Multan. Wheat sowing was completed on flat field after harvesting cotton late in January. Normal recommended agronomic practices (3 -4 bags of diammonium phosphate (DAP) and 2-3 bags of urea ha-') were given at the time of sowing while two more applications of urea (2 bags ha - ') were provided with first and third irrigations. The crop was harvested in May. Trials under saline fields were conducted during 2000-200 1 at Postgraduate Agriculture Research Station (PARS) belonging to the University of Agriculture, Faisalabad. Wheat line 1076 and Inqlab were used as test material with or without hormone treatment (GULNAZet al. 1999). The experiment was conducted in a randomised complete block design using three replicates. Electrical conductivity of the soil ranged between 10-14 dS/m. Only two irrigations could be applied due to shortage of water and thus the crop was under drought stress through most of the growth period. RESULTS AND DISCUSSION Results of the trials conducted over three consecutive years indicated that stress tolerant wheat line 1076 produced continuously and comparatively higher grain yields in stressed fields compared to normal wheat fields (Table 1). Performance of wheat line 41 was also better than wheat cultivar Inqlab, which was used as check. During 2000-2001, wheat line 41 produced a grain yield of 4400 kg ha-' which was 36% and 25 Yn higher than Inqlab and wheat line Table 1. Grain yield obtained for three wheat cultivars growing under normal and stress conditions for three consecutive years Growth conditions
Grain yield (kg ha-') during the year 98-99
99-00
00-01
Normal Stress
2580 2580
3536 3185
WL-1076 3784 3300
3300 302 1
Normal Stress
2224 2510
3186 3020
WL-4 1 3018 4400
2809 31 10
Normal Stress
2427 2893
1830 2912
Inqlab 1552 2816
1936 2873
227
245
265
191
-
-
-
'
LSD
Mean
Low input and stress tolerant wheat germplasm
Hereditas 135 (2001)
213
Table 2. Contents of Nu+ and K+ and K+/Na+ ratio in three cultivars of wheat grown under stressed (St) and normal (Nor) conditions ~
Wheat cultivars
Na+, rnmol/l
K+, mmol/l
K+/Na+ ratio
St
Nor
St
Nor
St
Nor
1076 41 Inq
0.63 0.69 0.78
0.45 0.50 0.53
6.6 5.6 5.0
4.7 4.4 5.6
10.5 8.5 6.4
10.4 8.8 10.6
LSD
0.08
0.04
0.3
0.3
0.7
0.8
1076, respectively, on stressed wheat fields. The higher yield of wheat line 41 was due to the highest number of tillers ever observed in any commercial wheat cultivar grown in traditional wheat growing areas (unpubl.). This character has been transferred from Ae. cylindrica and is expressed in wheat line 41 selected from its cross with wheat cultivar Pak-8 1 (FAROOQet al. 1992). As mentioned earlier, Pak-81 was a high yielding variety but it was not stress tolerant and this was one of the reasons of its withdrawal from the field. Transfer of stress tolerance and profuse tillering characters from Ae. cylindrica have not only made it stress tolerant but compensated the reduction in yield that was anticipated to occur under saline conditions (SHANNON et al. 1994). Stress tolerance in wheat line 41 has also been attributed to a higher number of primary roots and greater root length compared to Inqlab (GULNAZet al. 1999). Also transferred from Ae. cylindrica is the character for high K + / N a f ratio (Table 2). It is evident from the results that both wheat lines 1076 and 41 possess the ability to maintain high K + / N a + ratio under stress conditions, as there was no considerable difference between the two growing under stressed or normal field conditions. Wheat cultivar Inqlab had comparatively low K + / N a + ratio and there was significant difference between the ratios exhibited under stressed and normal conditions. Since K + plays an important role in osmotic adjustment (MAATHUISand AMTMANN 1999), tolerance for stress in 1076, and 41 was comparatively high. To study additional reason(s) of stress tolerance in wheat line 1076, seeds were given hormone treatment before sowing under saline conditions as mentioned in Material and methods (GULNAZet al. 1999). Wheat cultivar Inqlab was used as check. Results obtained indicated a significantly higher straw and grain yield (42 (YOand 37 (YO,respectively) in wheat line 1076 compared to Inqlab under control conditions (Table 3). A further two-fold increase in grain and straw yield was observed due to seed treatment with
hormone that could be attributed to root modifications (GULNAZet al. 1999). Probably, the hormone treatment helped the plants in mitigating the negative effect of salinity (GARCIAet al. 1997) thereby enhancing the stress tolerance of wheat line 1076 more than Inqlab because of the differential response of the genotypes towards hormones (GULNAZet al. 1999). The importance of the germplasm in terms of economic feasibility is given in Table 4. In the normal field, approximately Rs. 7100 (the amount of land preparation is not included which may further increase the spending) are being spent to obtain a grain yield that is worth Rs. 27189 (32 %I higher) with a net profit of Rs. 20089 to the farmer. Under a stress situation, where compost fertiliser was applied along with urea, net investment was about 3550 only and a grain yield worth Rs. 29700 was obtained with a net profit of Rs. 26150 which is 23 % higher than the profit obtained form a normal field. The cultivation of this material is thus economically feasible for resource starved small farmers.
Table 3. Effect of seed treatment with growth hormone on straw and grain yield of commercial (lnglab) and stress tolerant (WL-1076) wheat Seed treatment
Dry matter yield, g/plot Straw
Grain
Total
Nil Treated
102.2a* 96.4a
Inqlab 22.la 26.6b
124.3a 123.0a
Nil Treated
145.2b 197.6~
Harvest index
WL- 1076 30.3b 175.5b 5 0 . 6 ~ 248.2~
0.18a 0.22b 0.17a 0.20b
YOincrease of WL-1076 over Inqlab Nil Treated
42.1 105.0
37.1 90.0
41.2 101.9
-5.6 -5.8
*Figures in a column sharing a similar letter are not significantly different from each other at 5 % level of probability.
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Hereditas 135 (2001)
Table 4. Comparison of normal and low input agricultural practices for input /output relationship of stress tolerant wheat Input/output
Water DAP Urea Compost Herbicide Total cost Grain yield Total income Net profit"
Agricultural practice Normal
Low input
100 % Rs. 3200 (6 bags) Rs. 2700 (6 bags) Nil Rs. 1200 Rs. 7100* 3020 kg Rs. 27,180 Rs. 20,080
50 %, Rs. 1600 (2 bags) Rs. 1350 (3 bags) Rs. 600 (1200 kg) Nil Rs. 3550 3300 kg Rs. 29,700 Rs. 26,150
All figures are on per hectare basis; price of wheat grain, Rs. 9 kg-'. d, low input farming gave 23% higher profit for stress tolerant wheat. *, cost of land preparation not included.
CONCLUSION AND SIGNIFICANCE Wheat is a major staple food of over 140 million people of the country and is being grown on about 8.3 million hectares with an annual production of about 19 million tonnes (ANONYMOUS 2000). The government has set the target to increase wheat production and wheat cultivated area by 2.9 % and 0.790/0, respectively by the year 2010. This is only possible by bringing under cultivation the saline/ stressed areas where wheat is not presently growing. To do this, a specific wheat genotype has to be tailored through transferring and recombination of gene(s) from wild species or through the induction of mutation. We have used the first approach primarily because the diversity for salt tolerance is enormous in 1990) which can be wild relatives of wheat (FAROOQ effectively utilised and secondly to enrich the existing crop biodiversity for its possible use in future. For example, transferring gene(s) from Ae. cylindrica, which is a genome contributing species, has made it possible to bring back into the field, two agronomically excellent wheat cultivars of the past, Pak-81 and LU-26. Only the addition of value in the form of stress tolerance has enabled these varieties to grow in the areas where none of them was growing before. Similarly, diversity created in the form of wheat line 1076 would be of manyfold significance. Due to its built-in stress tolerance, its cultivation in the fields with standing cotton crop will revolutionise wheat production in this area. This is because Pakistan is currently producing 10 million tones of wheat in the rice cultured and rain-fed areas and 9 million tones in the cotton areas where yields are low due to delayed
planting made in early January after the last picking of cotton. If the stress tolerant material like wheat line 1076 is available for cultivation in the cotton fields during the month of November (normal wheat planting month); an additional 3 million tonnes of wheat can be obtained which may help enormously to achieve the projected targets. Since this material has been developed in the fields with very low osmotic potential, it requires very low moisture for germination which is one of the limiting factors of wheat growth under saline areas (MASSand Poss 1989) and comparatively less irrigation than the others. A precious commodity like water can thus be economised. It requires only half the recommended dose of fertiliser and is therefore an environment friendly material. If cultivation of this material can save even 50 YO of fertiliser without compromising on yield, it will save about 9 billion rupees being spent on the import of fertiliser. It is because of such low input requirements that wheat line 1076 is being grown during the current season on 1000 hectares of land in the southern Punjab for seed multiplication because the resource-poor, small farmers, do not want inputintensive varieties. It could therefore be inferred, very safely, that biodiversity is a vital component of environment friendly, sustainable as well as dependable agriculture and should be saved, enhanced and created in order to save the future of agriculture.
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