Evaluation of Yield, Yield Components and Stress Tolerance Indices in Bread Wheat Cultivars at Post-anthesis Irrigation Cut-Off

Wheat grain yield reduction occurs in most wheat growing regions of Iran due to post-anthesis water stress. This research was conducted to evaluate yield and yield components of wheat cultivars in normal irrigation and post anthesis irrigation cut-off conditions as a split-plot arrangement based on a randomized complete block design with three replications during 2015-16 in College of Agriculture, Shiraz University, Shiraz, Iran. The main plots included irrigation regimes (normal irrigation until the end of the growth season and irrigation cut-off from flowering to maturity) and subplots composed of 20 bread wheat cultivars. The results showed that irrigation cut-off caused a significant reduction in biological yield (46.4%), grain yield (59%), harvest index (23.7%), number of grains per spike (27.1%) and 1000 grain weight (13.8%). The highest grain yield in normal irrigation (1002 gm-2) and post anthesis irrigation cut-off conditions (485.7 gm-2) was obtained from Danesh cultivar. Among indices, stress tolerance index (STI), mean productivity (MP), and geometric mean productivity (GMP) had positive and significant correlations with grain yield in stress and non-stress conditions. Therefore, it appeared that these indices might be suitable for identification and selection of wheat cultivars that are tolerant to post anthesis irrigation cut-off. In general, the results indicated that Danesh, Sirvan, Baharan, Jones and Symonyda cultivars out–yielded the remaining ones under both stress and non-stress conditions.