Genetic architecture of a heterotic cross between two populations of maize.

The nature and magnitude of variability in the interpopulation cross of 'Mezcla Amarillo Selection' (MAS), an introduction from CIMMYT, Mexico, and 'J607', a population developed in India using indigenous, American, and Yugoslavian germplasm, were studied. Interpopulation progenies developed by following the North Carolina Design I were evaluated at two locations. The additive genetic variance component in interpopulation cross,σ A(12) (2) , and in one population assuming the other population as tester,σ A12 (2) andσ A21 (2) were significant for all the traits evaluated, namely ear length, ear girth, kernel rows and days to silk, with one exception. For kernel rows, the dominance variance component,σ A(12) (2) , was also significant but it was smaller thanσ A(12) (2) . The variance component due to dominance X location interaction,σ DL(12) (2) , was significant for all traits except kernel rows. In the case of ear length and ear girth,σ DL(12) (2) was greater than the other components.σ AL(12) (2) ,σ AL12 (2) andσ AL21 (2) were not significant for any trait. Expected genetic advance indicated a superiority of half-sib reciprocal recurrent selection over full-sib reciprocal recurrent selection.