valuation of Drought Tolerance Indices and Yield Stability of Wheat Cultivars to Drought Stress in Different Growth Stage

Drought and moisture stress is the most limiting factor affecting growth and productivity of crop plants.In order to study the response of ten bread wheat cultivars to drought stress, a field xperiment was conducted in 2013–2015 years at the the Agriculture and environmental research center of Ardabili, located at Moghan, Iran. The experimental design was a Split-plot xperiment based on randomized complete block design with three replications under five Drought stresses (no irrigation) regimes: rainfed (T1), the tillering stage (T2), at booting stage (T3), after anthesis (T4), full irrigation (T5) and 10 bread wheat cultivars. Combined analysis of variance revealed significant genotypic differences for Yp, STI, GMP, MP, TOL and HAM. Significant differences were also observed between drought treatments for Ys, STI, GMP, MP, TOL, HAM, SSI, YSI and DI. Nine drought tolerance indices including stress STI, SSI, TOL, HM, GMP, MP, YSI, DI) were calculated based on grain yield under drought (Ys) and irrigated (Yp) conditions. Grain yield in stress (Ys) condition was significantly and positively correlated with STI, GMP, MP and HM. Grain yield in non-stress (Yp) condition was significantly positive correlated with STI, MP, GMP, TOL, HM and SSI and significantly negative correlated with YSI and DI.  Results of this study showed that the indices STI, GMP, MP and HAM can be used as the most suitable indicators for screening drought tolerant cultivars. The stability measuring of the GGE biplot polygon showed that, the performance of cultivars G3, G7 and G8 are highly variable (less stable), whereas cultivars G5, G1, G2, G10, G9 and G4 are highly stable. The cultivars G9 and G10 are more desirable than other cultivars that has both high mean yield and high stability.