Determination of drought tolerant genotypes in cowpea based on drought tolerance indices

In order to evaluate and drought tolerance selection in cowpea genotypes and to identify the best indices for drought tolerance، an experiment was conducted at research field University of Tehran in Karaj during 2011-2012 growing season. In this study، 31 cowpea genotypes were evaluated in a randomized complete block design (RCBD) with three replications under normal irrigation (non- stress) and drought stress (non- irrigation from flowering stage until the end of the growing season) conditions. Genotypes were evaluated by indicators of drought tolerance including mean productivity (MP)، geometric mean productivity (GMP)، stress tolerance index (STI)، stress susceptibility index (SSI)، tolerance index (TOL) and yield stability index (YSI). Based on correlation with the yield under stress and non-stress condition، four indices MP، GMP، HARM، and STI were selected as the best indicators for selection of tolerant genotypes. Biplot pattern revealed genotypes No. 6، 10 and 23 as tolerant genotypes and 28، 3، 9، 14، 26، 17، 20، 30، 27 and 12 as drought-sensitive genotype.