Comparisons of Response to Alternative Selection Procedures Initiated with Two Populations of Maize (Zea mays L.)1

Abstract

Experimental comparisons were made between full‐sib family selection and reciprocal recurrent selection for higher grain yield in populations of Zea mays L. following six selection cycles. The experimental populations involved two open‐pollinated varieties, ‘Jarvis’ and ‘Indian Chief,’ their F1 variety hybrid, and the variety composite formed by random mating the variety hybrid. Comparisons were made in terms of responses of the varieties themselves and the variety hybrid to both kinds of selection, and response of the variety composite to full‐sib selection.Significant increases in yield were observed after six selection cycles in six of the seven populations tested. The exception was the response of the Indian Chief variety to reciprocal recurrent selection, which was not statistically significant. Responses of both varieties to full‐sib family selection were 2.1 times greater than their responses to reciprocal recurrent selection. Response of the variety hybrid to reciprocal recurrent selection was 1.3 times greater than the response to full‐sib family selection. Response of the variety composite to full‐sib family selection was no greater than for Jarvis, which was the most responsive of the two varieties. Heterosis in the variety hybrid increased markedly after reciprocal recurrent selection, but showed little change after full‐sib family selection. An evaluation of five additional traits showed thatincreases in yield were generally accompanied by a change toward shorter plants, with lower ear height, more tillers, and more ears. No change in time of flowering was observed.