Estimation of genetic parameters and regression line analysis for yield and its components in maize

Abstract

Eight inbred lines of maize were crossed in half- diallel in spring season of 2002 to produce twenty eight F1 crosses. The parents and crosses were grown in Fall season of 2002 and in Spring season of 2003 using RCBD with four replicates to determine the nature and magnitude of gene effects through components analysis and graphic analysis for 50% silking date, plant and ear height, ear length, number of rows/ear, number of grain/row, kernel weight and grain yield/plant. Both the additive and dominance genetic variances were found to be significant for all characters, except for grain yield/plant where the additive genetic variance was not significant in Fall season. The estimates of dominance genetic variance were more than the additive one for plant and ear height, number of grain/row, kernel weight and grain yield/plant, while, it was inverse that in other characters, and this reflected the reduction of the values of the narrow sense heritability, and increased of the values of the average degree of dominance one for the mentioned characters and it was less than one for other characters, which indicated that the studied characters were under partial and over dominance gene action. Also the results showed that positive and negative alleles were not distributed equally among the parents for all characters. Indicating that from the estimates of the ratio H2/4H1 were different from 0.25, and excess of dominant genes in the parents for all characters, indicating that from the estimates of the ratio KD/KR were more than one. The graphic analysis suggested the presence of over dominance and genetic variability among parents for most characters. It was concluded from the results of this study that some inbred lines could be used in a breeding program to develop elite hybrids of higher yield/plant and other related traits.