Evaluation of drought tolerance screening techniques among some landraces of bread wheat genotypes

Selection for drought tolerance typically involves evaluating genotypes for either high yield potential or stable performance under drought stress. In order to select drought tolerant land races of bread wheat an experiment was conducted in a randomized complete block design (RCBD) with three replications under two different rainfed and irrigated conditions during the growing season 2010-2011. Thirteen drought tolerance indices including stress tolerance index (STI), geometric mean productivity (GMP), mean productivity index (MP), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI), yield stability index (YSI), drought response index (DRI), drought resistance index (DI), modified stress tolerance index (MSTI), relative drought index (RDI), abiotic tolerance index (ATI) and stress susceptibility percentage index (SSPI) were calculated and adjusted based on grain yield under drought (Ys) and irrigated conditions (Yp). Biplot analysis showed significant positive correlation between grain yield in the stress condition (Ys) with indicators STI, GMP, YI, and MSTI, accordingly they are discriminating drought tolerant genotypes at the same manner. Principal component analysis (PCA), indicated that first and second components justified 88.30% of variations among drought tolerance criteria. Screening drought tolerant genotypes using mean rank, standard deviation of ranks and rank sum (RS) distinguished genotypes WC4953S (20), WC-47572 (19) and WC-47574 (4) as the most droughts tolerant.