HERITABILITY AND GENETIC ADVANCE FOR AGRONOMIC, PHYSIOLOGIC AND YIELD TRAITS OF MAIZE UNDER HIGH PLANT DENSITIES

Heritability (h2b) and genetic advance (GA) from selection are prerequisites for starting a breeding program for developing plant density tolerant variety of maize. The objectives were to estimate phenotypic coefficient of variability (PCV), genotypic coefficient of variability (GCV), h2b and GA for maize traits under four plant density environments, namely 47,600 (D1), 71,400 (D2), 95,200 (D3) and 119,000 (D4) plants/ha and to identify maize selection criteria for high density tolerance. For each density environment, a randomized complete block design with three replications was used to evaluate 28 maize hybrids in two seasons. High estimates of GCV and PCV (> 20) were recorded by leaf area to produce 1 g of grain (LA/1gG), kernels/plant (KPP), grain yield/plant (GYPP), grain yield/ha (GYPH), anthesis-silking interval (ASI), penetrated light at ear (PLE), penetrated light at bottom (PLB) under all environments; the highest of them was LA/1gG (>36%), indicating the ample amount of variation among the hybrids. The traits GYPP and GYPH followed by LA/1gG, KPR, KPP, chlorophyll concentration index, leaf angle (LANG), ear height, PLE, PLB, ear leaf area, showed high h2b coupled with high GA as a percent of mean, indicating that selection for improving these traits would be highly efficient. The best environment that achieved the highest estimates of GCV, PCV, h2b and GA for yield and its components was the lowest plant density D1 (47,600 plants/ha), while those achieved the highest estimates for other traits were recorded from D3, D4 and D2 in a descending order. The traits GYPP, LA/1gG, KPP and LANG had a strong correlation with GYPH, high heritability and high genetic advance and therefore could be considered selection criteria for high density tolerance.