Study of genotype × environment interaction for grain yield of durum wheat genotypes under rainfed and supplemental irrigation conditions by GGE biplot

Determining adaptability and stability of crop varieties is one of the most important stages in plant breeding programs, which it is costly and is not easy to do due to genotype × environment (G×E) interaction effects. To study G×E interaction for grain yield in durum wheat, an experiment with 16 durum wheat genotypes was carried out in a randomized complete block design with three replications under rainfed and supplemental irrigation conditions at research field of Dryland Agricultural Research Sub-Institute (Sararood Station), Kermanshsh, Iran, during three growing seasons (2011-14). The GGE (G + G×E) biplot was applied to study G×E interaction. Combined analysis of variance showed significant differences (P<0.01) between genotypes, environments and G×E interaction effects. The G×E interaction variance was greater about two times than genotypic variance, indicating the possibility of existing environmental groups for genotype adaptation. The GGE biplot analysis indicated that the environments were classified into three mega-environments with winning genotypes. Biplot analyses identified the breeding line G13 (2169 kg.ha-1) as the best genotype with high yielding and stability performance. The breeding lines G3 and G15 with 1960 and 3041 kg.ha-1, respectively, had the highest mean yield under rainfed and supplemental irrigation conditions, indicating the superiority of these two lines than the check cultivar in the both rainfed and supplemental irrigation conditions. In conclusion, positive increase in yield and yield stability is attributable predominately to genetic improvement in durum wheat breeding lines under variable environments.