Genotype x Environment Interaction and Stability Analysis for Gran Yield of Diallel Cross Maize Hybrids Across Tropical Medium and Highland Ecologies

Genotype x environment (G x E) interaction is the differential performance of genotypes across environments, especially in the tropics where seasonal and spatial variability is large. This results in serious challenges of product selection across environments. The objectives of this study were to determine G x E interaction and yield stability of new diallel cross maize hybrids and to identify suitable genotypes for the medium and highland ecologies in Rwanda. Forty- five diallel cross maize hybrids and three commercial checks were evaluated in four locations representing the major agro-ecologies of Rwanda over three seasons. The data were subjected to genotype and genotype by environment interaction (GGE) biplot analysis, using Genstat statistical package. The analysis revealed two mega-environments which discriminated the hybrids. Two genotypes 3 (S1/S4) and 25 (S4/S5) displayed specific adaptation; qualifying them as candidates for further testing in respective mega-environments. Genotypes 3 (S1/S4) and 29 (S4/S9) demonstrated high yield and stability. Overall, the study revealed crossover interaction and there is need to breed for both broad and specific adaptation in these medium and high altitude environments.