Early Hybrid Testing in Tropical Maize: Are Molecular Markers Useful for Selecting the Parental Component?

Abstract

The combination of parental lines determines hybrid performance. Two methods for choosing parental components in early-generation hybrid testing were compared in the present study. The S1 lines of two tropical maize populations from Yunnan and Guangxi were selected either based on the yield performance of reciprocal half-sib progeny (conventional method) or the maximization of the genetic distance (GD) between S1 lines, calculated from the allelic information of fifty SSR markers. The GD between the two original populations was low, probably because of the narrow genetic base and only two generations of development. However, the weak positive correlations between the grain yield of F1 hybrids and the GD as well as the specific combining ability (SCA), indicated that selecting the parents of testcrosses based on their genetic distance could help identify optimal genotype combinations. Highyielding F1 hybrids could be undoubtedly produced by conventionally selecting the parents and without costly field testing. As some crosses of S1 lines resulted in high-yielding progeny, the populations from Yunnan and Guangxi could provide additional new heterotic patterns for tropical maize breeding.