Uni and Multivariate Methods to Estimate Stability of some Bread Wheat Genotypes

Fifteen bread wheat genotypes included twelve lines and three cultivars were evaluated during the two seasons of 2021/2022 and 2022/2023 under two nitrogen fertilization levels and three sowing dates at the farm of experiments of Faculty of Agriculture, Minia University, El-Minia, Egypt. Joint regression analysis of variance indicated that all mean squares of environments, genotypes, G x E interaction and E + (G x E interaction) were highly significant for all studied traits, indicating, genotypes considerably interacted with the different environments. For grain yield fed-1, five genotypes; lines 2, 13, 14, 24 and Giza 168 were considered stable where mean grain yield exceeded the grand mean, moreover, bi and S2di of them were insignificant from unit and zero, respectively. Line 13 recorded low ecovalence Wi% and CV%, confirming it was stable across the environments. Additive main effects and multiplicative interaction analysis showed highly significant differences among environments, genotypes and G x E interaction for all the studied traits. By genotype selection index, it could be discriminated L13, L14, L34 and Giza 168 as stable genotypes with high grain yield across environments, confirming the results of regression and deviation from regression.