The Estimation of Some Genetic Parameters and Heterosis through Half Diallel Crossing between Nine Inbred Lines of Maize

Thirty six of F1 generation produced using half diallel mating design in the autumn of 2016 between nine inbred lines of maize (Zea mays L.) were obtained. The 45th genotypes were sown on 22-07-2016 at the field of the Faculty of Agriculture, Duhok University/Iraqi Kurdistan Region, using Randomized Complete Block Design with three replications to estimate combining ability, gene action, average degree of dominance, heritability as well as heterosis. The significant estimates of GCA and SCA variances suggested the importance of both additive and non-additive gene actions for the expression studied traits. Parent (Ir – S4) was an excellent general combiner for yield and related traits. Parents (DKcc 6418, Max – S4, V – Poh – S4 and Sym – S5) were also good combiners for some of the important yield components. Some crosses showed desirable SCA effects for more than one characters. Furthermore, the significant positive SCA effect involved parents where one or both were related to good combiners. Additive genetic variance was significant for ear height, 300-kernel weight and kernel yield/plant, while values of dominance genetic and environment variances were significant for all studied characters. Dominance genetic variance was larger than additive genetic variance for yield component traits. The degree of dominance produced greater values than unity. Low estimates of narrow-sense heritability were observed, while high estimates of broad-sense heritability for all studied traits were observed. The maximum number of hybrids showed significant positive heterosis for kernel yield/plant and the hybrid [Agr – S4 × San – S4] had the highest positive heterosis for kernel yield/plant and 300-kernel weight.