Evaluation of drought tolerance in some bread wheat genotypes using drought resistance

The aim of this study was to assessment of drought tolerance in genotypes of bread wheat (Triticum aestivum L.). For this purpose twenty genotypes were evaluated using randomized completely block design with three replications in both stress and non-stress conditions during 2010-2011 growing season in the Campus of Agriculture and Natural Resources, Razi University, Kermanshah. Based on the potential (Yp) and stress (Ys) yields, fourteen quantitative criteria of drought tolerance including Stress Tolerance Index (STI), Tolerance Index (TOL), Stress Susceptibility index (SSI), Mean Productivity (MP), Geometric Mean Productivity (GMP), drought resistance index (DI ), modified stress tolerance index (MSTI), Yield Index (YI), Yield Stability Index (YSI) and Harmonic Mean (HAM), stress non-stress production index(SNPI), abiotic tolerance index(ATI), stress susceptibility percentage index (SSPI) were calculated for each genotype. The result of combined analysis of variance showed there were significant differences between genotypes for grain yield in both conditions. Result of correlation analysis between grain yield in both conditions with drought resistance indices showed that STI, GMP, MP, MSTI, HM, DI, YI and MSTI were the best indices for identifying high yielding genotypes in both conditions. Furthermore, results exhibited that STI and MP were the best indices among all evaluated indices for tolerant genotype identification. Based on these indices and biplot analysis, genotypes No. 4, 8, 16 and 19 comparatively identified as drought tolerant genotypes. 3D graphs, Bi-plot and cluster analysis and principal component analysis (PCA) confirmed these results.