THE GENETIC ANALYSIS FOR GRAIN YIELD AND COMPONENTS COMBINING ABILITY IN MAIZE UNDER TWO SOWING DATES

A field trial was conducted at the fields of Al-Latifyia Research Station for Agriculture Research Directorate / Ministry of Science and Technology in spring and autumn seasons 2013. A half diallel cross was conducted among six inbred lines of maize to produce 15 F1 single crosses in spring season. The seeds of parents and crosses were sown in fall season using R. C. B. D. with three replicates to analyse general and specific combining abilities and to estimate the effects under two sowing dates July 28th and August 7th. The results of genetic analysis showed that the mean squares of GCA and SCA were highly significant for all studied traits in both sowing dates, except number of ears per plant which only GCA was significant in first sowing date and number of rows per ear was only SCA was significant in second sowing date. The variance ratio 0f GCA to SCA was less than one for all traits, this implies that these were controlled by dominance effects. In the first sowing date the parental line SYN-55 was the best combiner for grain yield per plant. while in second sowing date the parental line AM-69 was the best combiner for kernel weight and grain yield per plant. Some hybrids showed desirable significant SCA effects for studied traits, in the grain yield per plant, the hybrid SYN-55 x ART-C-51 in the first sowing date and the hybrid AM-69 x ART-C-51 in the second sowing date was highest value 25.37 and 16.23 respectively. The results indicate that some inbred lines could be used in a breeding program to develop hybrids of high yield per plant and SCA to produce better grain yield hybrids.