Generation Mean Analysis for Yield and Yield Components in Maize (Zea mays L.)

The choice of selection and breeding procedures for genetic improvement of maize or any other crop largely depends on the type and relative amount of genetic components and presence of non-allelic interaction. In this study six generations (P1, P2, F1, F2, BC1 and BC2) from two crosses of corn, KE72012(P1) × K1263/1(P2) and B73(P1) × MO17(P2) were evaluated for several agronomic traits including yield and its components at Torough Agricultural Station of Khorasan Razavi Agriculture and Natural Resources Research Center, Mashhad, Iran, in the 2010 growing season. The experiment was carried out as a randomized complete block design with three replications. The results showed significant differences among generations for all traits in both crosses. Most of the additive, dominance, additive × additive, additive × dominance and dominance × dominance effects were significant indicating the importance of the additive, dominance and epistatic modes of gene action in controlling the agronomic characters in maize. However, dominance variance was more important than additive variance for most of the traits such as ear length, kernel number per row, kernel number per ear and grain yield, which justifies the production of hybrid varieties in maize. Broad sense heritabilities of traits were 0.29-0.87 and 0.42-0.87 for KE72012 × K1263/1 and B73 × MO17 crosses, respectively. The estimated number of genes for grain yield in the late maturing hybrid, KS 704 (B73 × MO17), was around 10, while in the early maturing hybrid, KSC400 (KE72012 × K1263/1), it ranged from 3 to 5.