GENE EFFECTS IN CORN (ZEA MAYSL.): I. SEPARATION AND RELATIVE IMPORTANCE OF GENE EFFECTS FOR YIELD

Abstract

A procedure is outlined for the separation, into six parameters, of gene effects affecting genetic variation of a quantitative trait. These parameters represent mean effects, additive and dominance gene effects, and the three types of digenic epistatic effects. Estimates of the parameters are obtained using the population means of two inbred lines, their cross, and descendants due to subsequent selfing and crossing. The relative importance of the different gene effects can be evaluated from the magnitude and significance of the estimates.Population means of six inbred lines of corn, and all possible F₁, F₂, P₁F₁, and P₂F₁crosses among them, were used to obtain estimates of the various gene effects for yield of shelled corn. Mean yield performance of the populations was obtained from four experiments grown at two locations in each of 2 years.With regard to the 15 crosses, the estimates of gene effects indicate that the dominance gene effects were quite important in the inheritance of yield. Estimates of additive gene effects were of low magnitude and many were non-significant. Epistatic gene effects were considered to be more important than additive gene effects in the inheritance of yield in the crosses studied. The additive × additive and additive × dominance gene effects were relatively more important than the dominance × dominance effects.