Estimation Of General And Specific Combining Abilities Of Some Maize Inbred Lines (Zea Mays L.)

Abstract

The study was carred out during two years (2002-2003), and each of two years seasons (Summer and Winter), at the Faculty of agriculture and natural resources demonstration farm of the University of Kassala, New halfa town, Sudan, with a view to get informations about heterosis and combining ability in 13 inbred lines of maize (Zea mays L.). In a line X tester fashion, nine lines were crossed to four testers. All the 36 F1, hybrids and their 13 parents were sown in lattice square design with three replications. Observations were recorded on, days to 50% tasselling, days to maturity, plant height, number of nodes per plant, stem diameter, plant height to first cob, number of ear per plant, number of total leaves carried on the stem, leaf area, percentage of cob barness, cob length, cob diameter, number of kernel rows per cob, cob weight, shelling percentage, 100-seed weight , yield per plant and yield ton per hectare. The analysis of variance mean squares dipicted significant (P„d0.05) differences among the tested entries, for most of the studied traits in both years and both season. The study revealed the existence of phenotpic variability. The across seasons analysis, showed significant (P„d0.05) differences among the evaluated accessions for most of the traits, at years, seasons and the interactions of years with seasons, years with genotypes, seasons with genotypes, years with seasons with genotypes emphasizing that, evaluation over more seasons and years is important. Marked positive heterosis were showed by several crosses for most of the characters examined and more pronounced effects were found for grain yield ton per hectare. Over all study of hybrid vigour, revealed that, about 8 crosses possessed maximum desirable characters and potentials for commercial hybrid production. The combining ability mean squares due to parents, parents versus crosses, crosses and lines X testers were significant (P„d0.05) for most of the characters. The percent contribution of lines, testers, and lines x testers to total variation among crosses, indicated that, days to 50% tasselling, plant height to first cob, number of kernel rows per cob, percent cob barness, shelling percentage, yield per plant and yield ton per hectare, were largely influenced by non-additive 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 ones. Inbred lines 75, 111, 176 and 177 were the best general combiners for number of leaves carried on the stem, cob length, cob diameter, cob weight, yield per plant and yield ton per hectare. The analysis of specific combining ability effects, showed that, hybrids 8x160, 8x176, 8x177, 45x65, 45x160, 45x176, 45x177 and 66x65 gave higher SCA effects for nine traits, including cob length, cob diameter, number of kernel rows per cob and yield ton per hectare.