Response to eight cycles of full-sib reciprocal recurrent selection for grain yield and standability in BS10 and BS11 maize populations

The full-sib reciprocal recurrent selection (FSRRS) is designed to improve the performance and the heterosis exhibited by the cross between two populations. FSRRS can be integrated with maize (Zea mays L.) breeding programs whose ultimate goal is to obtain of hybrid cultivars. A comprehensive evaluation of a medium- to long-term selection program of FSRRS in maize populations BS10 and BS11 was conducted to determine direct and indirect response to selection in BS10, BS11, and the cross of BS10 and BS11;FSRRS was effective in improving the performance of the population cross and the populations themselves for grain yield and moisture, prolificacy index, stalk and root lodging, and ear height. The largest rates of gain were observed for grain yield, prolificacy index, and resistance to stalk lodging. BS10Cn and BS11Cn populations exhibited less inbreeding depression for grain yield than BS10C0 and BS11C0, respectively. The testcrosses of the selected populations performed better than those of unselected populations. More vigorous inbred lines with better combining ability could evolve from BS10Cn and BS11Cn;The direct response observed in the interpopulation crosses was larger than the indirect response observed in the populations themselves. For grain yield that difference is reduced if the predicted means are adjusted for genetic drift effects due to small effective population sizes;FSRRS selected different alleles for a given locus in each population, in such a way that the heterozygosity of the population crosses increased over cycles of selection. High-parent heterosis also increased with selection, which indicates that the changes in gene frequency caused by FSRRS were for favorable alleles with dominance effects located at different loci in each population;The results of this research indicate that the FSRRS can be of great benefit, especially for maize breeding programs whose ultimate goal is the development of hybrid cultivars