GENOTYPE X ENVIRONMENT INTERACTION FOR AGRONOMIC TRAITS AND YIELD STABILITY OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES IN HARARGHE, EASTERN ETHIOPIA

Common bean is an important herbaceous annual grain legume in the world, chiefly grown as a source of protein, carbohydrates, vitamins and minerals in human diets. In Ethiopia, beyond promoting food, health and nutritional security, it covers the dominant part of the country’s pulses export contributing to the economy of the country.In an attempt to increase the productivity of the crop,several improved varieties have been released from national and regional research centers. However, the performance evaluations of the varieties before release were done in limited agro ecological environments. Therefore, the current study was conducted to investigate the effect of genotype x environment interaction on the growth, yield performance and stability of common bean varieties under low to high altitude areas of Hararghe, Eastern Ethiopia. Sixteen common bean genotypes were tested at six environments in experiment laid out in 4x4 triple lattice design during 2017/18 cropping season. The analysis of variance for each environment displayed the presence of significance differences among the genotypes and, combined analysis of variance over environments also showed significant differences among genotypes, environments and GEI for phenological and agronomic traits including yield. Further GEI analyses were conducted using AMMI model and ANOVA from AMMI model indicated genotype, environment and GEI accounted for about 4.65%, 84.27% and 6.28% of the total sum of squares, respectively for grain yield. The result indicated that environment contributed much to the observed variations in grain yield, suggesting the need to test common bean varieties at diverse environments. Four Varieties, Ayenew (2758.2 kg/ha), Kufanzik (2713.27 kg/ha), Haramaya (2667.38 kg/ha) and Gofta (2662.78 kg/ha) had the first, second, third and the fourth highest yield with 26.34, 24.29, 22.19 and 21.97% more yield over grand mean, respectively. The GGE biplot identified Rare and Hirna as more descrimnating environments and the former as the most representative and an ideal testing environment, which was able to provide unbiased information about the performance of the tested genotypes whereas the later was identified as the least representative testing environment. Considering most of the stability parmeters, viz. deviation from regression (S2 di), AMMI stability value (ASV), Cultivar superiority, GGE biplot and mean yield, the varieties Hirna and Ayenew were identified as the most stable with mean yields above the mean grain yield of all genotypes. In conclusion, the study was conducted at six environments per single cropping season with only sixteen genotypes. So the information generated gave an insight for further study using more diverse environments, seasons and genotypes to confirm the result of current experiment and generate more reliable information on the effect of genotype, environment and GEI on performance and stability of grain yield and yield related traits.