Studying the Genotype × Environment Interaction and Grain Yield Stability of Winter Oilseed Rape Mutant Lines Using Parametric, Non-Parametric and SIIG Index Methods

The genotype × environment interaction is a major challenge in studying quantitative characters because it reduces grain yield stability in different environments. In this regard, to analysis the genotype × environment interactions and to determine the yield stability of winter rapeseed mutant lines, 9 lines and 6 cultivars were evaluated in a randomized complete block design with three replications in six experimental field stations (Esfahan, Hamedan, Karaj, Kermanshah, Qazvin and Zarghan) during 2021–2023 croping seasons. The combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. According to the stability analysis results using the Eberhart and Russel method, the Talaye cultivar with higher grain yield than overall mean and regression coefficient equal to one (bi=1) was identified as the genotype with high general stability for all regions. Based on the simultaneous selection method for yield and stability (YSi), the lines Z-900-6, T-1200-1, and Talaye cultivar with the lowest values were stable, whereas Zarafam, Okapi and Express cultivars with the highest values were unstable. Also, based on the SIIG index, the lines Z-900-6, T-1200-1, and Talaye cultivar with having high SIIG values as well as higher grain yields that total average was recognized as superior genotypes from the point of stability and grain yield. According to the results of cluster analysis, Karaj, Zarghan, Kermanshah and Isfahan locations were located in a group that indicates these locations had high predictability and repeatability power.