Study of Combining Ability and Hybrid Vigor in Many Maize lines Zea mays L

In this study, nine pure maize lines were tested, in the analytical program (Line X Tester), during spring season 2020 to obtain individual hybrids which are 20. Parents and the resulting individual hybrid seeds were cultivated in the autumn season 2020 in accordance with random complete block design R.C.B.D. in three replicates to estimate the general and specific combining ability, some genetic parameters, and study the hybrid vigor by the best parents. The statistical analysis results showed significant differences between parents and individual hybrids for every studied character. Tester (ART-B-17) showed superiority with the highest positive effect of the general combining ability for grains number per row, weight of 300 grains and grains yield per plant where it gave 51.81, 7.71, and 45.74 respectively. The line (Zm4) has the most desired effect with regard to the general combining ability for the parameters; the hight of upper cob, plant height, number of grans per raw, number of cobs per plant and, weight of 300 grains, and single plant grains yield (10.53, 11.48, 2.89, 0.08, 29.28) respectively. The hybrid (Zm3 × ART-B-17) gave the highest wanted effect for the specific combining ability for the following traits; the height of upper cob, number of cobs per plant and single plant grains yield 13.34, 0.15 and 48.46 respectively. The genetic analytical results showed the presence of additive non-additive effects that control the parameters inheritance. Percentages of broad and narrow sense heritability for grains crop parameter reached 100 % and 30.95% respectively, while the average degree of dominance for the same parameter reached 2.11. the hybrid (Zm4 × S6) achieved the highest positive hybrid vigor for single plant grains yield (64.45%). In conclusion, this study showed the possibility to use some dominant parental crosses to obtain single hybrids with high grain yield because the single plant grains yield parameter was complying the effect of highly dominant genes.