Evaluation of genotype × environment interaction in durum wheat (Triticum turgidum var. durum L.) regional yield trials

The objective of this experiment was to analyze genotype × environment (GE) interaction for grain yield of 20 durum wheat genotypes to identify the yield stability and adaptability of genotypes using GGE biplot method as well as some univariate stability statistics. The genotypes were evaluated in three rainfed stations of Sararood (Kermanshah), Maragheh and Shirvan, Iran under both rainfed and supplemental irrigation conditions in three cropping cycles from 2015 to 2018. Combined analysis of variance showed significant differences among the genotypes, environments and GE interaction effects. The environment effect was accounted for the 81.9% followed by GE interaction for 5.2% and genotype for 2.1% of total sum ofsquare (TSS). The large size of the GE interaction variance relative to genotype, suggests the possible existence of sub-environmental groups and genotypes with high grain yield and specific adaptation. Mean grain yield of genotypes across all environments was 2649 kg.ha-1, and 2212 and 3303 kg.ha-1 under rainfed and supplemental irrigation conditions, respectively. The highest mean yield was observed for breeding line G15 (2622 kg.ha-1) under rainfed conditions, and G3 (3744 kg.ha-1) under supplemental irrigation conditions. The GGE biplot analysis could differentiate environments to sub-environmental groups with top yielding genotypes. According to GGE biplot, breeding lines G14, G15, G8, G16 and G11 were identified as ideal genotypes with high mean grain yield and yield stability performance. Based on stability parameters the high yielding breeding line G14 identified to have the most stable grain yiled. The environments belonged to Maragheh location with higher "discriminativeness and representativeness" ability was found as ideal location for evaluation of winter durum wheat germplasm. The results also showed genetic gains for high grain yield and yield stability for durum wheat breeding program under cold and temperate cold dryland conditions of Iran.