Genotype-by-environment interaction and yield stability for grain yield of quality protein maize hybrids under low and optimum soil nitrogen environments

Maize (Zea mays L.) yield performance is determined by the effects of genotype and environment, and genotype × environment interaction (GEI). A complete diallel crosses of 11 QPM inbred lines were evaluated under both low and optimum soil nitrogen environments to identify high grain yield performance and yield stability of single-cross hybrids in six environments. The results of analysis of variance showed that variations among hybrids attributable to genotypes (G), environments (E), and genotype × environment interactions (GEI) were significant for grain yield. The result of the AMMI analysis showed that grain yield performance of the genotypes was significantly affected by environments, genotypes and GEI across six environments. The GGE biplot showed the sum of the first and second principal component axes explained 61.66% of the total variation. Genotype TL156583 × TL156612 was identified as the best genotype among hybrids across six environments, and less stable than genotype MHQ138 which was the poorest genotype but stable across all environments. AMMI stability value identified TL155976 × TL156583, TL156583 × TL155932, and TL156579 × TL156583 as stable genotypes, and TL156583 × VL05128, TL156583 × TL147078, and TL156579 × TL155976 as unstable ones. GGE-biplot identified genotype TL156583 × VL05128 to be the winner in E₆ (Dire-Dawa optimum N) whereas genotype TL156612 × TL148288 was the winner in E₂ (Raare optimum N) and E₅ (Dire-Dawa low N). Genotype TL156579 × TL155976 won in E₁ (Raare low N) and E₅ (Dire-Dawa low N).