GGE Biplot Analysis of Genotype x Environment Interaction and Bean Yield Stability of Arabica Coffee (Coffee arabica L.) Genotypes in Southwestern Ethiopia

Coffee is the main Ethiopia’s most important agricultural export crop, which is providing about 25-30% of foreign exchange earnings. The estimation of stability performance of the cultivars becomes most important to detect consistently performing and high yielding genotypes. Eleven Arabica coffee genotypes were evaluated in southwestern part of the Ethiopia across four locations for two consecutive years (2014/15 - 2015/16). The objective of the study was to estimate the presence of the interaction between genotypes and environments; and the stability performance of the coffee cultivars for its bean yield. The experimental design was Randomized Complete Block Design (RCBD) replicated twice in each testing location. Genotypes were evaluated by Genotype main effect and genotype x environment interaction (GGE) biplot. The combined analysis of variance indicated that genotypes, environments and GEI showed highly significant (p<0.01). Total variation explained was 41.63% for environments, 9.31% for genotypes and 32.32% for genotype by environment interaction (GEI). This obviously shows that the effect of the genotypes to the total variance was minimal when compare to the environment and the GEI. GGE biplot grouped the environments into four clusters with five genotypes being the winners in different group of environments. Top yielding cultivars namely; L52/2001 and L55/2001; and E6 (Jimma 2015/16) were identified as an ideal genotype and environment, respectively. In this study, stable genotypes, suitable environment for each of the coffee genotype and environment similarity based on bean yield were identified.