Genetic investigation of drought resistance in bread wheat using graphical methods: GGE bi-plot and AMMI model

To study the genetics of drought tolerance in bread wheat, the bi-plot of diallel data was used. Parents (Alvand, Bezostaya, Navid, Roushan, Gaspard, Sardary and Shahriar) and their crosses (without reciprocal crosses) were studied in 2007 using a Randomized Complete Block (RCB) design with three replications under normal and stress conditions. Analysis of variances indicated significant differences among genotypes for all traits. The GGE bi-plot graphical as well as AMMI methods were used for evaluation of cultivar potential. Investigated traits were 1000 kernel weight, kernel weight per plant, spike weight, spike length, plant height, awn length, peduncle length and kernel number per spike. For 1000 kernel weight, Roushan cultivar was the best general combinator. Moreover, Navid and Shahriar cultivars were the best specific combinatory, so that Navid × Shahriar cross was the best hybrid and for all other traits, the Alvand × Sardary was the best hybrid. These results were confirmed by AMMI method. Alvand cultivar was the best tester for 1000 kernel weight. For kernel weight per plant, Roushan cultivar, for spike weight, spike length, plant height and kernel number per plant Gaspard cultivar and for awn length and peduncle length Sardary and Alvands cultivars had the highest general combining ability.