GENETIC AND ENVIRONMENTAL EFFECTS OF PROLIFICACY IN RELATION TO MAIZE YIELD

Abstract

The number of ears per plant or prolificacy is an important yield component in maize varieties adapted to rainfed conditions. The objective of this study was to analyse the genotype × environment interaction in the expression of prolificacy and to estimate genetic effects and their relationship with grain yield in maize. Four lines were included, two selected for prolificacy and two non-prolific. Direct and reciprocal crosses were made between a prolific and a non-prolific line; in each case, backcrosses to both parents and respective F₂ were obtained. Prolificacy (PRO), flowering asynchrony (ASI) and grain yield (REND) were considered in this study. The genotype × environment interaction (IGA) was analysed. For each cross and respective filial generations, heterosis and additive genetic effects, dominance and epistatic effects were estimated. PRO and REND were found to depend on environmental conditions, with mean values of 5.53 and 3.53 Mg ha^-1 and 1.25 and 1.10 for yield and prolificacy in the two contrasting locations. Prolificacy interacted with environment in similar proportions to grain yield, while heritability for prolificacy was higher than for grain yield with values 0.63 vs. 0.41. The heterosis estimate depends on the specific crosses and it reached respective average values of -13 and 186% in prolificacy and yield. Additive genetic effects determined the expression of prolificacy and flowering asynchrony, while the dominance effect determined grain yield. In the crosses, when the prolific line was used as the male parent, epistatic additive × dominance effects were present in flowering asynchrony, prolificacy and grain yield.