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. 168 and TWC 352. The
experiment was conducted at two planting dates on 15th
May and 15th
June at the Agric. Res. and Experimental
Station of the Fac. of Agric., Moshtohor Benha University. The randomized complete blocks design with three
replications was used in this study. Significant mean squares due to crosses (C), inbred lines (L), testers (T) and
line x tester (LxT) were found for most studied traits of both and across sowing dates. Variance for C, L, T and
LxT with sowing dates interaction on the most studied traits was significance. δ2
SCA played the major role in
determining the inheritance of all traits. The magnitude of the interaction of δ2
SCA x sowing date (SD) was
generally higher than for δ2
GCA x SD. This finding indicates that non-additive is more affected by SD than additive
and additive x additive. Three crosses exhibited significant superiority over high check hybrid S.C. G 168. The
best top crosses were T3xL2 and T3xL15 at both and across sowing dates. Also, ten top crosses at combined analysis
did not differ significantly than the best check hybrid for the mention trait. L2, L7, L14 and L15 were good general
combiners for grain yield plant
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and L9, L10 and L13 for earliness. The top-cross T1 with each of inbred lines 2,
5 and 6, T2 with each of L1 and L12 and T3 with each of L3,L4 and L12 for earliness; T1xL11, T1xL12, T1xL14,
T2xL3, T2xL12 and T3xL2 for grain yield plant
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gave the best effects.