| چکیده انگلیسی مقاله |
To evaluate the effect of terminal heat stress on grain yield and its components in 20 spring bread wheat cultivars, a field experiment was conducted in Mollathani (35 Km Norh-east of Ahwaz) in 2007-2008 and 2008-2009 cropping seasons-using stripe block design with three replications. Four sowing dates (06 Nov., 06 Dec., 05 Jan. and 04 Feb.) were assigned to horizontal plots and 20 spring bread wheat cultivars (Shoeleh, Arvand 1, Chenab 70, Chamran, Vee/Nac, Atrak, S-80-18, Star, Inia 66, Bolani, Bayat, Darab, Dez, Kavir, Maroon, Hamoon, Hirman, Pishtaz and Roshan) were randomized in vertical plots. Results showed that year, sowing date, genotypes and sowing date × genotype had significant effect on all measured traits. Mean comparisons revealed that grain yield in 2008-2009 was greater than 2007-2008. Of the highest average grain yield (6049 kg.ha-1) was produced in 06 Nov. and lowest average grain yield (1755 kg.ha-1) was produced in 04 Feb. sowing dates. Cv. Chamran produced the highest average grain yield (5020 kg.ha-1) and the lowest average grain yield belonged to Inia 66 (3663 kg.ha-1). Using stress tolerance index (STI) classified Arvand (0.394), Vee/Nac (0.393), Chamran (0.378) and Bayat (0.356) as tolerant cultivars and Roshan (0.199), Hamoon (0.223), Falat (0.227), Star (0.233), Inia 66 (0.237) and Darab 2 (0.244) as susceptible cultivars to terminal heat stress. Generally, in Ahawaz conditions, adapted wheat cultivars with suitable maturity (early, mid and late maturity) and appropriate agronomic packages would result in stable high grain yield and sustainable production. |