A field experiment was carried out in the fields of the Field Crops Department - Faculty of Agricultural Engineering Sciences. The study included five inbred lines (ZM43W (ZE), ZM60, ZM49W3E, ZM19, CDCN5), given numbers 1, 2, 3, 4 and 5) to study the hybrid vigor and both general and special combing ability (GCA, SCA) of the half diallel mating method, for the spring and fall seasons (2016). The genetic analysis shows that all crosses gave a positive hybrid vigor for grain yield per unit area at the two population densities. the highest value is 116.20% for cross (3´5 )at low density, and 89.22% for cross( 1´4 )at high density. The hybrid vigor for all crosses is positive at two densities for dry matter yield, crop growth rate and ears weight. The highest value is 81.31%, 96.30% and 131.45% at high density for these traits for the cross (1´2), respectively. Also, this cross gave the highest value at high density for grain yield per plant (170.61%) and (85.43%) for no. of grain plant-1. The general combining ability in two densities for all studied traits. The highest positive value was (48.949) for parent 3 at low density. All values of s2sca are more than values of s2gca, and all values of s2D are more than all values of s2A. For this, all h2n.s. were low. It ranges from 1.88% for the crop growth rate to 18.82% for no. of rows ear-1 at low density and between -0.38 for the crop growth rate to 41.42 for 300-grain weight at high density. Because the values of s2D are higher than values of s2A, the values of the ratio of s2gca/s2gsca were less than one, while the value of were mor than one. This indicates that all these traits are influenced by dominance genes, and the importance of the non-additive gene action and its large contribution to the inheritance of these traits. Keywords: maize, combining ability, heritability, genetic parameters.
