Genotype x Environment Interaction for Durum Wheat Grain Yield and Selection for Drought Tolerance in Irrigated and Droughted Environments in Iran

Abstract

Durum wheat is grown in the Mediterranean region under stressful and variable environmental conditions. In a 4-year-long experiment, 14 genotypes (including 11 durum breeding lines, two durum (Zardak) and bread (Sardari) wheat landraces, and one durum (Saji) newly released variety) were evaluated under rainfed and irrigated conditions in Iran. Several selection indices (i.e. stress tolerance index (STI), drought tolerance efficiency (DTE), and irrigation efficiency (IE)) were used to characterize genotypic differences in response to drought. The GGE biplot methodology was applied to analyze a three-way genotype-environment-trait data. Combined ANOVA showed that the year effect was a predominant source of variation. The genotypes differed significantly (P < 0.01) in grain yield in the both rainfed and irrigated conditions. Graphic analysis of the relationship among the selection indices indicated that they are not correlated in ranking of genotypes. The two wheat landraces and the durum-improved variety with high DTE had minimum yield reduction under drought-stressed environments. According to STI, which combines yield potential and drought tolerance, the