GENETIC VARIABILITY FOR YIELD AND YIELD RELATED CHARACTERS IN EARLY TO MEDIAM MATURING YELLOW MAIZE (Zea may s L.) AT CHIRO, ETHIOPIA.

Abstract

Twenty five maize (Zea mays L) genotypes were evaluated in randomized complete block design for genetic variability and association between agronomic traits at Haramaya University at Chiro campus. Data were collected on 20 quantitative traits. The analysis of variance showed that the mean squares due to genotype were highly significant (p<0.01) for all trait studied, which indicates the existence of sufficient genetic variability and the potential for selection and improvement of the traits. High phenotypic and genotypic coefficients of variations were observed for plant height, ear height and grain yield and aboveground biomass. Also the difference between genotypic and phenotypic coefficients of variation were low in the traits for days to75% maturity, leaf width, ear diameter, number of rows per ear and harvest index indicating less environmental influence on these traits. High heritability estimates were obtained from days to75% maturity, days to silking, plant height, leaf width, number of nodes per plant, 1000-kernels weight, kernels texture, above ground biomass, grain yield per hectare and internodes length. These traits, therefore, may respond positively due to selection. Estimates of genetic advances as percent of mean at 5% selection intensity ranged from 3.6% for number of plant at harvest to 76.4% for above ground biomass. Genotypic correlation coefficients were found to be higher in magnitude than that of phenotypic correlation coefficients, which clearly indicated the presence of inherent association among various traits. At phenotypic level, days to silking, days to maturity, plant height, ear height, number of ears at harvest, internodes length, ear length, days to anthesis, leaf width and number of nodes per hectare was observed to have positive and highly significant (P<0.01) correlation with grain yield per hectare and negative and highly significant (P<0.01) correlation with harvest index. Path coefficient analysis at phenotypic level based on grain yield as dependent variable revealed that days to anthesis, days to maturity, ear height, leaf width, number of nodes per plant, number of ears at harvest, above ground biomass and harvest index showed positive direct effect. The genotypic path analysis also indicated that above ground biomass and harvest index showed positive and significant correlation, therefore, these traits are more important than other traits for the genetic improvement of maize for yield.