Evaluation of Variability, Combining ability and Heterosis in Some Local Genotypes of Maize (Zea mays L.)

Abstract

Number of experiments was carried out on three locations in Blue Nile State, namely Damazin Research Station, Jebreel and Rosarise, Sudan for two consecutive years (2007/2008 and 2008/2009) to estimate heterosis and combining ability in 18 locally genotypes of Maize (Zea may L.) . In a genotype x tester fashion, 16 genotypes were crossed with tow testers. All the 32 F1 genotypes and their 18 parents were sown in a randomized complete block design with four replications. Data were recorded on, days to 50% tasselling, days to maturity, plant height, number of nodes per plant, stem diameter, kernel plant height to first cob, number of ears per plant, number of leaves carried per plant, leaf area, percentage of cob bareness, cob length, cob diameter, number of kernel rows per cob, cob weight, shelling percentage, 100 seed weight, grain yield per plant and grain yield per hectare. The analysis of variance deitected significant (P≥ 0.05) differences among the tested entries, for most of the studied traits in both seasons. The cross year analysis, showed significant (P≥ 0.05) differences among the evaluated accessions for most of the traits, at both season, and the interaction of years with season, years with genotypes, seasons with genotypes, years with genotype emphasizing that, evaluation over more year and years is important Marked positive hetrosis were showed by several crosses for most of the characters examined and more pronounced effects were found for grain yield (t/h). Overall study of hybrid vigor revealed that, about 12 crosses possessed maximum desirable characters xiii and potential for selection. The combining ability mean square due to parents, parents versus crosses, crosses and genotype x tester were significant (P≥ 0.05) for most of the characters. The percent contribution of line, testers, and genotype x testers to total variation among crosses, indicated that, days to 50% tasselling, plant hightheight to first cob, number of kernel rows per cob, percent cob bareness, shelling percentage, yield per plant and yield ton per hectare were largely influenced by nonadditive gene effects, while stem diameter, number of total leaves per plant, leaf area, cob length, cob diameter, cob weight and 100 seed weight, were largely governed by additive gene effects, genotypes B1, B2, D1, D5 and R2 were the best general combiners for number of leaves per plant, cob length, cob diameter, cob weight, yield per plant and yield ton per hectare. The analysis of specific combining ability (SCA) effects showed that genotypes M45XB1, M45XB3, M45xB5, M45XR3, H1XD1, H1XD4 and H1XR5 gave higher specific combining ability (SCA) for yen ten characters including stem diameter, number of nodes per plant, number of total leaves per plant, number of ears per plant, percent of cob barness, cob length, cob diameter, number of kernel rows per cob, yield per plant and yield ton per hectare.