Interpretation of Genotype x Environment Interactions for Early Maize Hybrids over 12 Years.

Genotype x environment interaction was investigated for grain yield of early maize (Zea mays L.) hybrids. Data were obtained from the French Association Generale des Producteurs de Mais trial network and included 132 hybrids and 229 environments over 12 yr, following an unbalanced design. Analysis of genotype x environment interaction was done for the 1-yr data sets, for the two successive years data sets, and for the 12-yr data set. The magnitude of genotype x environment interaction variance was equal to, or greater than the genotypic variance. Interaction effect was modeled by factoria