Genotype x environment interaction and stability analysis of grain yield in QPM hybrid varieties

Maize (Zea mays L.) is a major staple cereal widely cultivated in different agro-climatic environments of Ethiopia. Maize productivity in the tropical highland region of the country is known by low average yield mainly due to the lack of high yielding and widely adapted improved cultivars. The objectives of this study were to determine G×E interaction and yield stability of quality protein maize (QPM) experimental hybrids,to identify ideal genotype with high average yield depending on the differential genotypic responses to environment, and to form homogeneous grouping of environments. The study was conducted at seven environments representing the tropical-highland sub-humid maize growing agro-ecology of Ethiopia in 2015/2016. Thirty-three QPM hybrids and three-commercial hybrid checks were evaluated using a 4 ×9 alpha lattice design. Yield data was analyzed using AMMI and GGE bi-plot methods. Using AMMI analysis, four promising QPM hybrids designated asG31, G7, G19, G29, and G22 were identified based on combined stability and average yield.GGEbi-plot displayed that variety Jibatwas closest to the ideal genotype, can be considered as best hybrid whereas G29, G22 were considered as desirably stable genotypes. GGE bi-plot also displayed Holeta as ideal environment and thus considered useful in discriminating the hybrids and representativeness as suitable environment. The GGE analysis delineated the test environments into three mega-environments useful for targeted evaluation of genotypes. The result of this study indicated specifically and widely adapted high yielding stable genotypes and also revealed homogeneous test environments.