Utilization of Line X Tester Model for Evaluating the Combining Ability of Some New White Maize Inbred Lines

Abstract

This investigation was carried out to study the combining ability effects of 18 parents of maize (15 inbred lines and 3 testers) crossed in line x tester scheme for phonological, plant and yield characteristics. A yield trial included the 45 top crosses, 15 inbred lines, 3 testers along with the two check hybrids S.C. 10 and TWC 310. The experiment was conducted at two planting dates on 29 April and 17 June at the Agric. Res. and Experimental Station of the Fac. of Agric., Moshtohor Benha University. The experimental design was randomized complete blocks with three replications. Mean squares due to crosses (C) inbred lines (L), testers (T) and line x tester (LxT) were significant for most studied traits of both sowing dates as well as for the combined analysis. Significance of interaction variance for C, L, T and LxT with sowing dates on the most studied traits was detected. δ 2 SCA played the major role in determining the inheritance of all traits, revealing that the largest part of the total genetic variability associated with these traits was a result of nonadditive gene action. The magnitude of the interaction of δ 2 SCA x sowing date (SD) was generally higher than for δ 2 GCA x SD. This finding indicates that non-additive type of gene action is more affected by SD than additive and additive x additive types of gene action. The top crosses L3, L6, L9, L10 and L15 x T1 (L 2060), L14 and L15 xT2 (SC Hw1) and L3, L4, L5, L6, L7, L9, L11, L14 and L15 x T3 (Giza 2) did not differ significantly from SC10. Also, all TWC's (all inbred lines xT2) had higher grain yield plant -1 than TWC 310. Inbred lines No 6, 9, 14 and 15 were good general combiners for grain yield plant -1 and L4, L5 and L7 for earliness. For grain yield plant -1 and earliness the top-cross L4xT3 gave the best ij S ^ effects.