Effects of Visible Recessive Alleles on Vigor Characteristics in a Maize Hybrid1

Abstract

Present knowledge of the control of heterosis and various vigor characteristics on a single gene or locus basis is inadequate. Information on this subject was obtained by producing a number of mutant recessive alleles in a maize (Zea mays L.) inbred line and selecting 31 for study. It was obvious from observation that most of the recessive alleles exhibit numerous pleiotropic effects affecting various vigor characteristics in the homozygous background of the inbred. Five of the recessive alleles were selected for this study to ascertain if pleiotropic vigor effects may also be expressed in the heterozygous background of a hybrid. Each allele produced an array of pleiotropic effects, either positive or negative, affecting various vigor characteristics in the hybrid. Considering pleiotropic effects in the context of single gene differences, the effects on individual vigor characteristics range from small to large. One allele increased the grain yield by three percent. The genetic nature of the pleiotropic effects is not clear at this time; however, it is proposed that pleiotropic effects associated with recessive alleles provide a genetic basis for heterosis.