Interpopulation Genetic Variance after Reciprocal Recurrent Selection in BSSS and BSCB1 Maize Populations

Abstract

Reciprocal recurrent selection is a breeding procedure designed to improve two populations simultaneously by selecting for performance in the interpopulation cross. The objective of this study was to evaluate the effects of II cycles of selection on the mean, genetic variance, and correlations amongtr aits in the interpopulationc ross of the Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic no. 1 (BSCBI) maize (Zea mays L.) populations. Oneh undredr eciprocal full‐sib families from Cycle 0, Cycle 5, and Cycle II of the interpopulation cross between BSSS and BSCBI were evaluated at two locations in 1989 and three locations in 1990. Grain yield increased 0.25 Mg ha‐1 per cycle (6.46%) after II cycles of selection, grain moisture increased 0.85 g kg‐1 per cycle, root lodging decreased 0.23%, and stalk lodging decreased 1.64% (all changes significant at P = 0.01). Estimates of genetic variance for all traits were significantly different from zero, except for root lodging in Cycle II. Genetic variance for grain yield decreased after II cycles of selection, although the differences among cycles were not significant. Root lodging, stalk lodging, anthesis date, and silking date had significant decreases in genetic variance after II cycles of selection. Changeisn heritability generally paralleled changes in genetic variance. Genotypic and phenotypic correlations were seemingly unchangeda cross cycles of selection. The results indicate that reciprocal recurrent selection has been effective in increasing the mean performance of the population cross while maintaining genetic variance.