A half diallel cross between 10 inbred lines of maize (Zea mays L.) was evaluated under two different planting dates for ealiness, yield and its components.. planting date, genotypes, parental inbred lines, crosses and parent vs crosses were significant for all studied traits at each and across planting dates except for, parental inbred lines for grain yield plant-1 at each and across planting dates. Significant interaction mean squares between parental inbred lines and planting dates were obtained for all traits except days to 50% silking.
Significant mean squares associated with general (GCA) and specific (SCA) combining abilities were detected for all traits under study. GCA/SCA ratio was computed. For, grain yield plant-1 at both and across planting date as well as No. of kernels row-1 at D2 and combined data low values which less the unity were detected, indicating that the largest part of the total genetic variability associated with these traits was a result of non-additive type of gene action. For all remain cases, there showed the highest GCA/SCA ratio, indicating that greatest role of the additive and additive x additive types of gene action in the expression of this trait
Significant interaction mean squares between planting dates and general combining ability were detected for all traits except GCA x D for days to 50% sillking and 100-Kernel weight. Meanwhile, Insignificant interaction mean squares between planting dates and specific combining ability were found for all studied traits except grain yield plant-1. the parental inbred lines P4 and P9 to be the best general combiners for earliness and grain yield plant-1, respectively.
The favorable ( ) effects were observed in the crosses P1xP3, P1xP8, P3xP7 and P6xP8 for days to 50% silking and P1xP5, P1xP6, P1xP8, P1xP9, P5xP7, P6xP7 and P7xP9 for grain yield plant-1 in both sowing dates and the combined analysis.
The lowest genetic similarity (0.289) was detected between P3 and P8. While, the highest genetic similarity was (0.824) scoured between the two parental inbred lines P8 and P9.
The estimate value of correlation coefficient between GD, and mean performance for grain yield plant-1 found negative (r =-0.045). Therefore, the RAPD marker could not be predicted about the mean performance for grain yield plant-1 in this study.
Key wards: Maize, Combining ability, Genetic distance, RAPD Marker.
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