Genetic Analysis of Half Diallel Crosses of Inbred line of maize. (Zea mays L.)

Abstract

Half Diallel crosses performed according to Griffing method (1956) ,second method fixed model by using seven pure Lines of maize (Agr-183, ZM47W, CML494, IK58, ZP505, ZP670, ZP197), in the farm at the Tuz district / Salahaddin governorate in autumn 2014 season. Parents and their crosses in addition of check variety (Drachma) were grown at autumn of 2015 by using Randomized Completely Block Design with three replications for studying general and specific combining abilities, gene action and other genetic parameters. Studied traits were: (days to 50% male and female flowering(day) , plant height(cm) , leaf area of the main ear(cm2) , number of ears.plant-1, number of the rows.ear-1 , number of the grains.row-1, weight of 300 grains(gm) and single plant yield(gm). The genotypes ( parents and their hybrids and commercial cross )showed significant differences at 1% level probability for all studied traits except number ears.plant-1 of parents which was significant at 5% probability. Mean square of general combining ability was highly significant for all characters. The ratio of general to specific combining ability components to specific combining ability was less than one for all characters under study except days to 50% female flowering was greater than one. The parent (6) has a good general combiner for most character but the crosses (1×5) , (2×4) , (4× 6)were a good specific combiner for all character except the number of rows.ear-1 for hybrid (1×5) and the number of ears.plant-1 for hybrids (2×4), (4×6). Dominance gene action appeared more important than additive one in controlling the inheritance of all studied characters , and the heritability at broad sense was high for all the traits than heritability in narrow sense. Values of broad sense of heritability were medium for the traits : plant height, number of ears, number of the grains in the row, weight of 300 grains and single plant yield and a high of number of days to 50% male flowering and female flowering. The average degree of dominance exceeded one for all characters indicated the presence of over dominance except number of days to 50% female flowering was less than one which that means the presence of partial dominance .