About 32% of the 99 million ha wheat grown in developing countries experiences varying levels of drought stress. Three major drought types have been identified: Late drought (LD) is common in the Mediterranean region, early drought (ED) is found in Latin America and wheat is produced on residual soil moisture (RM) in the Indian subcontinent and part of Australia. Until 1983, CIMMYT selected all germplasm under near optimum conditions for its yield potential and tested only advanced lines under drought. In spite of many critics, this approach proved to be successful, since in the mid 80's CIMMYT germplasm was grown on 45% of the wheat area in LC with annual rainfall from 300–500 mm and on 21% in areas with less than 300 mm. Since 1983, CIMMYT's drought breeding methodology is to alternate segregating populations between drought stressed and fully irrigated conditions (FI) and to test advanced lines under a line source irrigation system. To compare the efficiency of these approach, yield of four, mostly leading varieties, from each of the regions with LD, ED, RM, and FI and twelve recent CIMMYT cultivars selected for high yield under FI and RM conditions (ALT) were compared under four different moisture regimes (FI, LD, ED, and RM) in 89–90 and 90–91 in Yaqui Valley, Mexico. Genotypic correlation between yield and days to flowering, days to maturity, height, grains m-2, TKW, test weight and grain fill period were calculated.
Mean grain yield of the four best lines in the ALT group was highest under all moisture stress regimes, followed by the FI-group. However, the highest yielding cultivar within each moisture regime was from the FI-group under FI, from the LD-group under LD, and from the ALT-group under ED and RM conditions. Estimates for genetic advance suggest that FI is the best environment for increasing grain yield even in all three drought environments. This indicates that yield potential per se is beneficial also in drought environments. The highest yield in drought environments was realized by the CIM cultivars selected under FI and RM. Simultaneous evaluation of the germplasm under near optimum conditions, to utilize high heritabilities and identify lines with high yield potential, and under stress conditions to preserve alleles for drought tolerance seem at present the best strategy.
Key wordsbreeding methodology drought patterns input-efficiency wheat Triticum aestivum
Unable to display preview. Download preview PDF.
- Bramel-Cox P.J., T. Barker, F. Zavala-Garcia & J.D. Eastin, 1991. Selection and testing environments for improved performance under reduced-input conditions. p. 29–56. In: Plant Breeding and Sustainable Agriculture: Considerations for objectives and methods. CSSA Special Publication No. 18. CSSA and ASA, Madison, USA.Google Scholar
- Byerlee D. & P. Moya, 1993. Impacts of international wheat breeding research in the developing world, 1966–1990. CIMMYT, Mexico, D.F. 135 pp.Google Scholar
- Calhoun D.S., G. Gebeyehu, A. Miranda, S. Rajaram & M.van Ginkel, 1994. Choosing evaluation environments to increase wheat grain yield under drought conditions. Crop Sci 34: 673–678.Google Scholar
- Ceccarelli S., M.M. Nachit, G.O. Ferrara, M.S. Mekni, M. Tahir, J.Van Leur & J.P. Srivastava, 1987. Breeding strategies for improving cereal yield and stability under drought. p. 101–114. In: J.P. Srivastava, E. Porceddu, E. Acevedo & S. Varma (Eds). Drought Tolerance in Winter Cereals. John Wiley & Sons, New York. 387 pp.Google Scholar
- Cooper M., D.E. Byth & D.R. Woodruff, 1994. An investigation of the grain yield adaptation of CIMMYT wheat lines to water stress environments in Queensland. II. Classification analysis. Agric Res 45: 985–1002.Google Scholar
- Duvick D.N., 1990. Ideotype evolution of hybrid maize in the USA, 1930–1990. p. 557–570. In: ATTI Proceedings, Vol. II, II National Maize Conference: research, economy, environment. Grado (GO)-Italy September 19–20–21, 1990. centro regionale per la sperimentazione agraria, pozzuolo del friuli edagrocole s.p.a., Bologna, Italy.Google Scholar
- Duvick D.N. 1992. Genetic contributions to advances in yield of U.S. maize. Maydica 37: 69–79.Google Scholar
- Ethaie B., J.G. Waines & A.E. Hall, 1988. Differential responses of landrace and improved spring wheat genotypes to stress environments. Crop Sci 28: 838–842.Google Scholar
- Edmeades G.O., J. Bolanos, H.R. Lafitte, S. Rajaram, W. Pfeiffer & R.A. Fischer, 1989. Traditional approaches to breeding for drought Resistance in Cereals. p. 27–52. In: F.W.G. Baker (Ed). Drought Resistance in Cereals. ICSU, Paris and C.A.B. International, Wallingford, England.Google Scholar
- ICARDA, 1993. Cereal Program. Annual Report for 1992. ICARDA.Google Scholar
- Morris M.L., A. Belaid & D. Byrelee, 1991. Wheat and barley production in rainfed marginal environments of developing world Part I of 1990–91 CIMMYT world wheat facts and trends. CIMMYT, Mexico, D.F. 51 pp.Google Scholar
- Rajaram, S., M. van Ginkel & R.A. Fischer, 1994. CIMMYT's wheat breeding mega-environments (ME). In: Proceedings of the 8th International Wheat Genetic Symposium, July 19–24, 1993. Beijing, China (in press).Google Scholar
- Rajaram, S. & M. van Ginkel, 1995. Wheat breeding methodology: international perspectives. Proceedings 20th Hard Red Winter Wheat Workers Workshop. Oklahoma City, USA (in press).Google Scholar
- Uddin N., B.F. Carver & A.C. Clutter, 1992. Genetic analysis and selection for wheat yield in drought-stressed and irrigated environments. Euphytica 62: 89–96.Google Scholar
- Van Ginkel, M., D.S. Calhoun, G. Gebeyehou, A. Miranda, C. Tianyou, R. Pargas Lara, R.M. Trethowan, K. Sayre, J. Crossa & S. Rajaram, 1995. Plant traits related to yield of wheat in early, late, or continuous drought conditions (in press).Google Scholar
- Villareal, R.L., E. Del Toro, A. Mujeeb-Kazi & S. Rajaram. The 1BL/1RS chromosome translocation effect on yield characterization in a Triticum aestivum L. cross. Plant Breeding (in press).Google Scholar
- Zavala-Garcia F., P.J. Bramel-Cox, J.D. Eastin, M.D. Witt & D.J. Andrews, 1992. Increasing the efficiency of crop selection for unpredictable environments. Crop Sci 32: 51–57.Google Scholar