Genotype by environment interaction and stability analysis for selection of superior fodder yield performing oat (Avena sativa L.) genotypes using GGE biplot in Ethiopia

Twenty-four oat genotypes were evaluated in nine environments during the 2020/2021 cropping season using a randomized complete block design with three replications. The pooled analysis of variance showed that fodder dry matter yield was significantly affected by genotype, environment, and genotype by environment interaction (GEI). The result revealed that the higher fodder-yielding genotypes which located at the left side of the average-environment coordinate (AEC) ordinate were G6, G10, G3, G2, G7, G4, G23, G24, G15, G19, G13, and G9. Among these high-yielding genotypes, G6 G23, G9, G10, G3, and G15 had relatively shorter vector projections from the arrowed AEC abscissa or lower PC1 scores indicating better stability of these genotypes across environments. The ideal genotype which located at the center of the concentric circles was G6 while the desirable genotypes were G10, G3, G23, and G2 which located relatively closer to the ideal genotype. The ‘which-won-where’ view of the GGE biplot indicated that the environments were grouped into two mega-environments (MEs). The first ME included E7, E1, E8, E3, E9, E2, and E4 and its vertex genotypes were G6 and G2 while the second ME contained E5 and E6 with the vertex genotype of G13. Among the environments, E7 was an ideal environment which had higher discriminating ability and representativeness while E1 and E8 were favorable environments. Based on the performances of fodder yield and stability across environments, G6, G23, G10, and G9 were selected and recommended for verification in the central highlands of Ethiopia.