Genotype-by-environment interaction and yield stability of quality protein maize hybrids developed from tropical-highland adapted inbred lines

Maize (Zea mays L.) yields are significantly lower in the tropical-highlands than other environments predominantly due to the lack of well-adapted and improved cultivars and due to genotype by environment (G x E) interaction. The objectives of this study were to determine G x E interaction and yield stability of quality protein maize (QPM) single-cross hybrids recently developed from tropical-highland adapted inbred lines, and to identify promising genotypes and representative test and seed production environments. The study was conducted at seven environments representing the tropical-highland sub-humid maize growing agro-ecology in Ethiopia. Sixty-six QPM hybrids and two commercial check hybrids were evaluated using a 4 x 17 alpha lattice design. Data were analysed using the additive main effects and multiplicative interaction (AMMI) and genotype and genotype by environment (GGE) biplot methods. Using AMMI analysis, four promising QPM hybrids were identified compared to the commercial checks and designated as hybrid 10 (KIT32 x 142-1-eQ), hybrid 66 (142-1-eQ x CML144), hybrid 59 (FS60 x 142-1-eQ), and hybrid 38 (FS67 x CML144) with grain yields of 10.3, 9.6, 9.4 and 8.9 t ha(-1), respectively. The same hybrids were identified as the best performers for being close to the ideal cultivar using the GGE biplot analysis. The GGE analysis delineated the test environments into two mega-environments useful for targeted evaluation of genotypes and effective maize breeding and seed production. Kulumsa site during 2013 (KUL13) was the most suitable environment in discriminating the QPM hybrids and being a representative test environment.