Combining Ability, Phenotypic and Genotypic Correlations of Diallel Crosses in Yellow Maize Evaluated Under Two Nitrogen Levels.

Abstract

Six yellow inbred lines of maize, were setup in a half diallel crosses mating design, to produce 15 F1 hybrids. All genotypes with the three commercial checks : SC 155, SC 162 and SC 170 were evaluated using the two nitrogen levels : 80 and 120 kg N/fed during the 2007 growing season at Sakha Agriculture Research station Kafr El-Sheikh. The aim of this study was to estimate the phenotypic and genotypic correlations, GCA, SCA and their interactions with the two nitrogen levels. The results would also identify the superior genotypes for yielding performances. The studied traits were : grain yield (Ard./fed)., ear length (cm), ear diameter (cm), number of rows / ear and weight of 100 kernels(g).The results indicated the presence of significant differences among genotypes for most studied traits .This finding was expected due to the different origin of the parental inbred lines.General combining ability (GCA) and specific combining ability (SCA) mean squares were significant or highly significant for most studied traits under both nitrogen levels. The interactions between GCA and SCA with nitrogen levels were not significant for all studied traits except for SCA x N which was significant for weight of 100 kernels(g).The values of SCA mean squares were higher than those of GCA mean squares for grain yield (Ard./fed.), No. of rows / ear and weight of 100 kernels(g) traits. All means were higher under the high nitrogen level than the low nitrogen level for all studied traits.The best general combiners for grain yield (Ard./fed.) were the inbred lines: Sk 5001/50 and Sk 7070/62.The single hybrids Sk5001/50 x Sk 5005/ 12, Sk 5002/9 x Sk 5005/16, Sk 5001/50 x Sk5005/16 and Sk 5002/9 x Sk 5001/5 showed positive significant SCA under the two nitrogen levels for grain yield Ard./fed.The phenotypic and genotypic correlations among the five studied traits were positive for all studied traits.

Estimation of combining ability and superiority percentage of half diallel crosses between yellow maize inbred lines for growth characters and some diseases resistance

“…The ratio of GCA x Y / SCA x Y mean square found to be exceeded the unity for all traits, indicating that the additive gene effects were more interacted with years than non-additive ones for all traits. These results agreed with those obtained by Abd El-Hadi et al (2005) which reported that, the mean squares of GCA and SCA were highly significant for all studied traits i.e. ; days to 50% silking, plant height and ear height.…”

“…While, Cr vs. Ch x Y interaction was highly significant for 50% silking date and significant only for ear height and resistance to late wilt disease. The obtained results were in good harmony with those reported by Abd El-Hadi et al (2005) where they found that, the difference among genotypes and crosses were highly significant for days to 50% silking, plant height and ear height. While, the interaction between genotypes x years exhibited significant differences for days to 50% silking.…”