Combining Ability for Grain Yield and Some Other Traits and Classification of New Yellow Maize Inbred Lines into Heterotic Groups Using Line × Tester

Seven new yellow maize inbred lines were topcrossed with three testers, i.e.; SC-180, SC-173 and SC-168 during 2023 summer season at Ismailia Agric. Res. Station. The 21 testcrosses and the two yellow check hybrids TWC-368 and TWC-377 were evaluated at Ismailia, Sakha and Mallawei Agric. Res. Stns. during 2024 summer season. Results revealed that the mean squares of locations, genotypes, crosses and their interaction with locations were significant for all studied traits. Variances of lines, testers, line x testers and their interaction with locations were significant for most of the studied traits. Results showed that five crosses, L4 x T3, L5 x T3, L6 x T3, L2 x T1 and L3 x T2 had significantly and good mean performance values toward earliness, short plant, lower ear placement and high yield ability. The inbred line L3 was the best general combiner toward high yielding ability and T1 as a tester possessed the good general combiner for grain yield toward high yielding. While, L4 and L6 had general combining ability negative and significant for silking date toward earliness and T2 as a tester was the best general combiner toward earliness, short plant, short ear height and lower ear placement. Three crosses; L2 x T1, L3 x T2 and L5 x T3 possessed positive and significant SCA effects toward high yielding. Results based on HSGCA method helps the plant breeders to make a good combination between different lines from different heterotic groups to produce superior hybrids having high yield and earliness.