responses of yield, yield components and drought resistance indices in bread and durum wheat cultivars to post-anthesis drought stress

wheat grain yield is adversely affected by post-anthesis drought stress conditions in most wheat growing areas of iran. to evaluate the effect of late drought stress on wheat cultivars, a field experiment was conducted as split plot in a completely randomized block design with four replications at experimental farm of collage of agriculture, shiraz university during 2009-2010 growing season. irrigation regime (normal and cut off after flowering) and wheat cultivars were in main plots and subplots, respectively. there were ten bread wheat and five durum wheat cultivars. the result showed that post-anthesis drought stress reduced biological yield, grain yield, number of grain per spike, 1000 grain weight, and harvest index significantly. maximum grain yield in the normal irrigation and late season drought stress was detected in moghan2 and shiroudi, respectively. mean productivity (mp), geometric mean productivity (gmp) and stress tolerance index (sti) showed positive and significant correlation with yield in both stress and non-stress conditions. it appeared that mp, gmp and sti were appropriate indices for selection of cultivars resistant to late season drought stress conditions. in this experiment, moghan2 and adl cultivars showed higher potential yield as well as greater relative resistance to late season drought stress.