Wright, G.C. Dr; Ph: (07) 4160 0700; Fax: (07) 4162 3238; firstname.lastname@example.org
Research organisation: Queensland Department of Primary Industries, Farming Systems Institute, PO Box 23, Kingaroy Qld 4610
Sponsor: ACIAR: Australian Centre for International Agricultural Research
1. To identify and select in India peanut cultivars with high water- use efficiency (WUE) and partitioning characteristics from the world germplasm collection and genetic material from applied peanut breeding programs;
2. To evaluate the yield performances of these parent lines or progenies in appropriate target environments in India;
3. To determine the extent of cultivar variation in WUE, and its correlation with carbon isotope discrimination, harvest index, and the relationship of these traits to seed yield in soybean, cowpea, chickpea and navy bean.
Methodology: The project is to be divided into 2 major sub-projects in order to achieve the above objectives. (I) Selection for high W and HI in peanut Indian national program and ICRISAT personnel will initially screen a subset of the world germplasm collection to identify lines with high WUE (via the correlated trait of SLA) and high harvest index (HI) characteristics. Up to 100 of these lines will be grown in the field under both irrigated and drought stressed conditions at up to 7 locations in India, differing in drought patterns. Measurements of total dry matter, pod yield, phenology, light interception, specific leaf area and harvest index will be taken. Simple mobile rainout shelters will be used at each site to allow a common stress treatment to be imposed on a subset of selected lines. Data will be analysed using the recently published methods of Williams and Saxena (1991), where the physiological determinants of pod yield can be calculated from simple physiological models. (ii) Assessment of genotypic variation in W in soybean, cowpea, chickpea and navy beans. Glasshouse and field studies to determine the extent of genotypic variation in W, and its correlation with delta, will be conducted in both India and Australia. Food legumes including soybean, chickpea, navy bean and cowpea will be studied. Initial germplasm evaluations for variations in delta, SLA and HI will be conducted under non-stress conditions in the relevant germplasm collections. A subset of cultivars for each species with contrasting delta characteristics will be assessed for W variation in pot studies in the glasshouse. These cultivars will then be re-evaluated for W variation in field grown canopy situations, using the mini-lysimeter facility developed during the peanut improvement project (see Wright et al., 1988). Measurements of cumulative water use, total, vegetative and root biomass, soil water relations, SLA, HI and delta analyses will allow detailed analysis of the extent of W variation among cultivars, as well as assessing any negative associations with other growth parameters.
Progress: The project has made significant progress in several areas, and a summary of how project outputs have been achieved is summarised below:
1. A number of groundnut cultivars with high W, T and HI characteristics have been identified and their pod yield performance been assessed to be superior to local checks in a range of contrasting environments differing in water availability. The combined analysis of multi-location trials (MLT's) demonstrated that high pod yield under droughted conditions was associated with a combination of average to above average levels of T, W and HI, and there is clear evidence that these traits are not physiologically linked. The challenge for future breeding efforts will be to combine high levels of each trait in the same genotype, ideally with expression of broad adaptation in contrasting water environments.
2. The project has confirmed that SLA is a reliable correlated measure of Δ ( and hence W) in groundnut, in agreement with previous studies in Australia and India. Over three years of MLT's, a strong correlation between Δ and SLA has been observed over a range of contrasting locations and water regimes. A combined analysis of MLT's has indicated that genotype x environment interaction for the SLA/W trait is moderately high, however further analysis has shown that certain genotypes are stable over a range of environments and could be suitable as parents in crossing programs aimed at selecting for this trait.
3. The project has demonstrated that simple and easily measured physiological traits such as SLA and HI could be successfully used to enhance yield improvement in groundnut breeding programs. The key to the adoption of physiological traits in breeding programs is that they are simply and inexpensively measured. The approach outlined in our project considers that groundnut breeders should be able to analyse germplasm/variety/selection trials with considerably more depth, for a modest investment in new measurements. For instance, the additional measurements of SLA, ABIO and daily climate data can allow the breeder to more fully understand the physiological basis of any observed superior pod yield performance, as well the nature of any G x E interaction.
4. The project has identified large genotypic variation in W in soybean, navybean, chickpea and cowpea. In soybean and navybean, very close relationships between Δ and W were observed in glasshouse and field lysimeter experiments. The relationship between SLA and W was very strong in navybean, but non-existent in soybean. The reason for this differing response was thought to be associated with differences in the contributions of photosynthetic capacity versus stomatal conductance to W variation. In the navybean genotypes tested, W variation was mainly associated with capacity as evidenced by a strong correlation between specific leaf N and W. In soybean, it appears that both high capacity and low conductance contribute to higher W.
5. The situation with chickpea is unclear, with large genotypic variation being observed, but poor correlation with Δ and/or SLA in both glasshouse and field studies. In addition, chickpea appears to have substantially lower overall W compared to peanut, soybean and navybean. Whether this observation is a function of the small germplasm range tested or a real species difference needs to be assessed. If correct, the observation implies that there may be substantial gains in W to be made for enhanced drought resistance in chickpea.
6. A total of 7 scientists visited Australian institutions and studied techniques relating to measurement and future selection of the W trait in legume breeding programs, as well as contributing to data analysis of the Indian MLT data. The commencement of crossing programs using genotype identified as having high W, T and HI characteristics has begun in a number of collaborating centres in both India and Australia. The approaches developed in this project will be further refined and utilised in the next phase of the ACIAR project (CS1/97/114).
7. The project has achieved a very high level of communication, with numerous papers published or submitted for publication in a range of scientific journals, conference proceedings and newsletters for both Indian and Australian research components.
Period: starting date 1993-07; completion date 1998-07
Keywords: : peanuts; Arachis hypogaea; grain-legumes; water use efficiency; selective breeding; crop yield; Harvest index; Leaf area index; drought resistance
Hall, A.E., Richards, R.A., Condon, A.C., Wright, G.C. and Farquhar, G.D. (1994). Carbon isotope discrimination and plant breeding. Plant Breeding Reviews 12, 81-113.
Jayalaakshmi, V., Reddy, P.V., Asalatha, M. and Vasanthi, R.P. (in press). Genetic variability for water-use efficiency traits in groundnut. Legumes Research
Jayalaakshmi, V., Raja Reddy, C., Reddy, P.V. and Nageswara Rao, R.C. (in press). Genetic analysis of carbon isotope discrimination in groundnut (Arachis hypogaea L.). Journal of Oilseeds Research
Nageswara Rao, R.C., Udayakumar, M., Farquhar, G.D., Talwar, H.S. and Prasad, T.G. (1995). Variation in carbon isotope discrimination and its relationship to specific leaf area and ribulose-1,5-biphosphate carboxylase content in groundnut genotypes. Australian Journal of Plant Physiology 22, 545-51.
Robertson, M.J., Carberry, P.S., Wright, G.C. and Singh, D.P. (in press). Using models to assess the value of traits of food legumes from a cropping systems perspective. In Proceedings of the International Food Legumes Conference, Adelaide, September, 1997.
Subbarao, G.V., Johansen, C., Nageswara Rao, R.C. and Wright, G.C. (1994). Transpiration Efficiency - Avenues for Genetic Improvement. In Handbook of Plant and Crop Physiology, Marcel Dekker, Inc. Chapter 39, pp. 785-806.
Turner, N.C., Wright, G.C. and Siddique, K H M (in press). Adaptation of grain legumes to water limited environments: Selection for physiological, biochemical and yield component characteristics for improved drought resistance. In Management of Agricultural Drought: Agronomic and Genetic Options, edited by N.P. Saxena, ICRISAT Publication.
Udayakumar, M., Sheshshayee, M.S., Nataraj., K.N., Aftab Hussain, I.S. and Prasad, T.G. (1996). Dual (13C and 18O) isotope discrimination in plants - Can this be a potential tool to identify desirable physiological traits associated with water use efficiency? In The Changing Scenario in Plant Sciences, Prof Mohan Ram Commemoration Volume, pp. 388-418.
Udayakumar, M., Sheshshayee, M.S., Nataraj, K.N., Bindu Madhava, H., Devendra, R., Aftab Hussain, I.S. and Prasad, T.G. (1998). Why has breeding for water-use efficiency not been successful? An analysis and alternate approach to exploit this trait for crop improvement. Current Science 74, 994-1000.
Wright, G.C. and Nageswara Rao, R.C. (1994). Groundnut Water Relations. In The Groundnut Crop, edited by J.T. Smartt. Chapter 9, pp. 281-335, Chapman Hall (UK). Chapter 9, pp. 281-335.
Wright, G.C. and Nageswara Rao, R.C. (1994). Selection for water-use efficiency in grain legumes. Report of a workshop held at ICRISAT Centre, Andhra Pradesh, India, 5-7 May 1993. ACIAR Technical Reports No. 27, 70 pp.
Wright, G.C., Nageswara Rao, R.C. and Basu, M.S. (1995). A physiological approach to the understanding of genotype x environment interactions: A case study on improvement of drought adaptation in peanut. In Plant adaptation and crop improvement, edited by M. Cooper and G.L. Hammer, CAB (UK) Chapter 19, pp. 365-82.
Wright, G.C., Nageswara Rao, R.C. and Basu, M.S. (in press). A physiological approach to improve the identification and selection of drought adapted groundnut genotypes. In Management of Agricultural Drought: Agronomic and Genetic Options, edited by N.P. Saxena, ICRISAT Publication.
Numerous Other Conference and Newsletter articles are available on request