Reaction of spring bread wheat to post anthesis heat stress in Ahwaz, Iran

ABSTRACT: Grain yield of bread wheat (Triticum aestivum L.) is reduced by heat stress, particularly in reproductive phase, in many countries worldwide including Iran. In order to study the effect of terminal heat stress on grain yield and yield components of spring bread wheat cultivars, a stripe block arrangement was conducted using randomized complete block design with three replications in 35 Km north-east Ahwaz in 2008-2009 cropping season. The vertical plots included four sowing dates (06 Nov., 06 Dec., 05 Jan. and 04 Feb.) and 20 cultivars were randomized in horizontal plots. The results showed that sowing date, cultivars and their interaction had significant effects on all measured traits. The highest grain yield (6.15 t/ha) and the lowest grain yield (1.82 t/ha) were produced in sowing dates of 06 Dec. and 04 Feb., respectively. Chamran had the highest grain yield and the lowest grain yield was produced by Inia 66. The best combination was Chamran in 06 Dec. with grain yield of 7.25 t/ha and worst was Roshan in 04 Feb. with grain yield of 1.20 t/ha.