Combining ability and genetic parameters of some white maize (Zea mays L.) inbred lines using diallel analysis

Nine inbred lines (S5) of white maize derived from Giza -2 and IW- 469 were crossed using of half diallel cross mating design, during spring season of 2019 at the Farm of Faculty of Agriculture, Al-Azhar University at Assiut Branch, to produce thirty six F1 crosses. The parents, crosses and tow checks i.e. SC-163 and SC-10 were evaluated during spring season of 2020 in R.C.B.D with three replications to determine combining ability, heterotic and gene action effects. Significant differences were found among parental and their crosses as well as for general combining ability (GCA) and specific combing ability (SCA) for all studied traits. The previous results indicating the importance of both additive and non-additive genetic effects for studied traits. The ratio of Σg2i/ΣS2ij was less one for all studied traits, indicate that the non-additive gene action in the inheritance of all the studied traits. Parents P1 and P4 showed best GCA effects for grain yield/plant, while the parents P2 and P6 appeared to be the best general combiners for most of the studied traits. The crosses P1 x P8, P2 × P6 and P2 × P5 appeared to be the best mean performance, SCA and superiority percentage for most studied traits. The values of the broad sense heritability were high (>80%) for all studied traits. While, the narrow sense heritability was low for grain yield/plant (13.00%). Results indicated that some inbred lines could be used in breeding program to develop single crosses which have higher grain yield.