Author : Bliss Aquino Aday

Summary : Design I experiments were conducted to estimate some genetic parameters in maize using Cuba Gpo. I x Eto Amarillo and Cuba 40 x Cupurico Composites. Characters studied were grain yield, grain-stover ratio,
days to silking, ear leaf area, leaf angle and number of leaves. No estimates of genotype x environment interactions were obtained.

Days to silking, ear leaf area, leaf angle and number of leaves gave comparatively high estimates of heritability while grain yield and grain-stover ratio were observed to have lower heritabilities. Estimates of genetic correlations of days to silking, leaf angle and leaf area with grain yield were highly significant.

Six index selection methods were constructed based on the estimates obtained from the Design I experiments. Two methods used were essentially Smith's indexes where the objective is to maximize gains in selection for one primary character. The other four methods were developed for simultaneous improvement of earliness and grain yield, a case where the two desired traits are negatively correlated. Expected gains using these methods were estimated and their implications to breeding procedures
discussed.

Highly significant observed or realized gains were obtained from one cycle of full-sib family selection for earliness, erect leaves, small and large leaves. However, no significant observed gains in selection for grain yield and grain-stover ratio were obtained. The selection for earliness gave the highest grain yield
in the experiments when planted at a density of 80,000 plants per hectare.