EFFECT OF TERMINAL HEAT STRESS ON YIELD AND YIELD COMPONENTS OF SPRING BREAD WHEAT CULTIVARS IN AHWAZ, 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 design was conducted using randomized complete block design with three replications in 35 Km north -east Ahwaz in 2007-2008 cropping season. The vertical plots included four sowing dates (06 Nov., 06 Dec., 05 Jan. and 04 Feb.) and 20 cultivars (Atrak, Arvand1, S -80-18, Star, Inia66, Bolani, Bayat, Pishtaz, Chamran, Chenab70, Darab, Dez, Roshan, Shoeleh, Kavir, Maroon, Hamoon, Hirman and Vee/Nac) were randomized in horizontal plots. The results showed that sowing date, cultivars and their interaction had significant effects on all measured traits. The highes t grain yield (5.949 t/ha) was produced in sowing dates of 06 Dec. and the lowest grain yield (1.690 t/ha) was produced in sowing dates of 04 Feb. Chamran had the highest grain yield and Inia66 had the lowest grain yield. Maximum grain yield (7.039 t/ha) r elated to Chamran in 06 Dec. and the minimum grain yield (1.219 t/ha) belonged to Falat in 04 Feb.