Abstract:
Fifteen inbred lines and three testers of maize were crossed in line x tester
scheme to study the combining ability effects for earliness, grain yield and
yield components. A yield trial included the 45 top crosses, 15 inbred lines,
3 testers and two check hybrids S.C. Pioneer 3084 and T.W.C Giza 352. The experiment
was conducted for three years at the Agricultural Research Station of the Faculty
of Agriculture, 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 for the combined analysis over two evaluation seasons. Significance of
interaction variance for C, L, T and LxT with seasons on most studied traits
was detected. δ2SCA played the major role in determining
inheritance of all traits, revealing that the largest part of the total genetic
variability associated with these traits was a result of non- additive gene
action. The magnitude of the interaction of δ2SCAxyears
(SY) was generally higher than for δ2GCA x SY.
This indicates that non-additive type of gene action is more affected by SY
than additive and additive x additive types of gene action. Inbred lines M L4,
8, 9, 10, 11 and L12 were reliable general combiners for earliness and M L3,
4, 5, 6 and L13 for grain yield plant-1. For earliness the top-cross
M 212D x SC (M 201xM 204) gave the best Sij effects. Regarding grain yield plant-1,
five SC between M L 204 and each of inbred lines M 232A, M 202C, M 242A, M 212D
and M 236B as well as the two TWC M 202cxSC (201x204) and M 236BxSC (201x204)
showed significantly and out yielded than check hybrid SC Pioneer 3084 by 18.99%, 12.67%, 15.71%, 11.29%, 14.11%, 10.55% and 6.56% in the combined analysis,
respectively.
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