A half diallel cross between 7 inbred lines of maize was evaluated at two different sowing dates for nine
quantitative characters. Sowing date and crosses mean squares were significant for all traits under study. Significant
crosses x sowing date mean squares were obtained for all studied traits except, No. of rows/ear. General and specific
combing ability mean squares were significant for all traits. For days to tasseling and days to silking at early sowing
date; ear height, No of rows/ ear at late sowing date; No of kernels/row and 100-kernel weight at early sowing date
and combined analysis, high ratios GCA/SCA which largely exceeded the unity were obtained, indicating that a large
part of the total genetic variability associated with these traits was a result of additive and additive by additive gene
action. For No of rows/ ear at the combined analysis, the ratio equal to one this mean additive and non-additive gene
action are similar in controlling this case. For remain cases, showed GCA/SCA ratios less than unity. Therefore, it
could be concluded that the large portion of the total genetic variability for these traits was due to non-additive gene
action. The parental inbred line No. 6 and 4 seemed to be good combiner for grain yield/plant. Also, the parental
inbred line No. 3 exhibited significant desirable (
gi
ˆ
) effects for silking date and grain yield/ plant. The crosses P1xP3,
P1xP5, P2xP5, P2xP6, P2xP7, P3xP4, P3xP7, P4xP5, P4xP6, and P5xP6 had the highest values for SCA effects. The crosses
2x6 and 3x4 out yielded the check hybrid 168 by 7.1 and 7.9%, respectively in the combined analysis. |
