Genetic Studies of Extra Early Maize Genotypes Under Low Nitrogen

Abstract

Nitrogen (N) is a major limiting factor associated with maize production in sub-Saharan Africa. Low N tolerant hybrids can absorb and  utilise N from the soil as well as applied fertilisers, making them efficient users of N. This study focused on identifying inbred lines with  desirable GCA for grain yield and other agronomic traits under low N, determining the gene action governing grain yield and other  agronomic traits under low N and estimating the genotypic variability for grain yield and other agronomic traits among extra early maize  hybrids. Ten extra early white endosperm maize inbred lines were crossed to five testers in a line tester mating design to -1 generate fifty  (50) single cross hybrids (SCH) which were evaluated under low N (30 kg N ha ) -1 and optimum N (90 kg N ha ). The combined analysis of  variance (ANOVA) under low and optimum N showed significant mean squares for the environment and hybrids but non-significant hybrid environment interaction mean squares for grain yield (GY) under low N. General combining ability of line and tester as well as  specific combining ability showed significant mean squares for GYunder both low and optimum N environments. Non-additive gene  action governed GY under low and optimum N. GY had moderate genotypic coefficient of variability and high genetic advance as a  percentage of mean under low and optimum N. Lines CRIZEEL-W-242 and CRIZEEL-W-261 were the best inbred lines identified under low  and optimum N conditions, hence should be used in recurrent selection or other hybridization programmes.