Assessment of Drought Tolerance in bread wheatgenotypes Based on Resistance/ Tolerance Indices

ABSTRACT: In order to study the response of fifteengenotypes of wheat to drought stress, an experiment was conducted in a split plot based on randomized complete block design with four replications under two irrigated conditions during 2011-2012 cropping season. Fourteen drought tolerance indices including stress tolerance index (STI), stress susceptibility index (SSI), tolerance index (TOL), harmonic mean (HAM), geometric mean production (GMP), mean production (MP), yield index (YI), yield stability index (YSI), drought resistance index (DI), abiotic tolerance index (ATI), stress non-stress product index (SNPI), modified stress tolerance (MSTI), and stress susceptibility percentage index (SSPI) were calculated based on grain yield under drought (Ys) and irrigated conditions (Yp). Grain yield in stress (Ys) condition were significantly and positively correlated with Yp, STI, GMP, MP, HAM, YI, SNPI, DI, K1STI and K2STI and negatively correlated with SSI. Grain yield in non-stress (Yp) condition were significantly and positively correlated with STI, GMP, MP, HM, YI, SSPI, SNPI, ATI, K1, K2 and TOL. Grain yield in stresscondition negatively correlated with SSI.Results of this study show that these indices of stress tolerance/resistance such as K1STI, K2STI, SSPI, ATI, SNPI, and DI can be used as the most suitable indicators for screening drought tolerant cultivars. Cluster analysis classified the genotypes into three groups i.e., tolerant, susceptible and semi-tolerant or semi-sensitive to drought conditions. Therefore they are recommended to be used as parents for improvement of drought tolerance in other cultivars.