Stability and Adaptability Study for Seed Yield of Improved Faba Bean Varieties in the Highlands of Oromia Region, Ethiopia

Yield of a variety is the most complex trait and influenced by several factors. G x E interaction significantly influenced grain yield of faba bean suggested the presence of differentially adapted faba bean genotypes. The reliability of genotype performance across different environmental conditions is an important consideration in plant breeding. Thirteen faba bean genotypes were evaluated at five faba bean growing areas of Oromia highlands during 2017/18 main cropping season with the objective of determining the magnitude and nature of G x E interaction for grain yield of faba bean varieties and to identify stable high yielding variety(s) under wide production for the tested environments and similar agro-ecologies. Combined analysis for grain yield revealed highly significant (P<0.01) difference among varieties, locations and variety by location interaction. Walki (3.35 tons ha-1) was the highest yielding variety followed by Tumsa (3.10 tons ha-1), Gebelcho (3.08 tons ha-1) and Dosha (3.00 tons ha-1)with yield advantages of 24.07%, 14.80%, 14.07% and 11.11% compared to the grand mean, respectively. Stability analysis models used in the present study such as regression coefficient (bi) and deviation from regression (S2 di) variance (Wi) ecovalence, coefficient of determination (r2 i), cultivar superiority measure (Pi), stability variance (α2 i) and coefficient of variation revealed that Gebelcho, Shallo and Walki varieties were the most adapted across environment and accompanied with high mean grain yield. Conversely, varieties Holeta-2 and Mosisa were the most unstable. Overall, Dosha and Tumsa had specific adaptation to environments Bore and Alleyo, respectively, Alloshe at Uraga. Walki was also adapted to Gedo and Anna Sorra. Furthermore, Gebelcho Shallo and Walki had general adaptability hence can be recommended for wider production in the tested locations and similar agro-ecologies of the region.