The present investigation aimed to evaluate some maize inbred lines for their
combining ability and its behavior over different environmental conditions with respect
to the important traits. Therefore. possible combinations in a half diallel fashion were
made among five inbred Jines. The parental lines and their crosses were evaluated in
two years, 2001 and 2002 at Farm of S akha Agricultural Research S tation for t he
following traits: days to 50% silking, plant height, ear height, no. of kernels/row, no. of
rows/ear, ear length, ear diameter and grain yield per plant. The obtained results
could be summarized in the following: The variances among genotypes and their
partitions: inbreds, crosses and inbreds versus crosses were highly significantly
different for all the studied traits in the two years and combined, indicating that the
parental lines are different in their genetic constitutions. However, years and their
interactions with genotypes and their partitions mean squares were significant for
most of studied traits. Both general (GeA) and speCific (SeA) combining ability mean
squares were highly Significant for all the studied traits in the two years and combined.
indicating the contribution of additive and non-additive gene action in the genetic
expression of these traits. Furthermore, the SCA mean squares were larger in
magnitude than the corresponding values of GCA mean squares, which were verified
by GCA/SCA ratio with values less than unity for all the studied traits except no. of
rows/ear. This suggested the predominance of non-additive (dominance) genetic
variance in the inheritance of the studied traits except for no. of rows/ear, which was
mainly controlled by additive genetic variance. The inbred line L-7041 proved to be
the best general combiner among the inbred lines in breeding toward developing early
and increaSing of number of rows/ear. While, the inbred lines Sd-7 and Sd-34 were
the best general combiners for producing high yielding genotypes. Nso, the results
revealed that it is not necessary that parents having high general combining ability
effects would also contribute to high SCA effects. Thus, the crosses (Gz-628 x l-
8084), (Sd-7 x L-7041) and (L-7041 x L-8084) were defined as superior combinations,
which showed the highest SCA and heterotic effects in most of studied traits. In conclusion, iudging by heterotic values general and specrnc combining ability as
well as genetic variance components, the production of corn hybrids is the best
breeding program for the improvement of these traits.