Combining Ability and Heterosis for Yield and Yield Components in Maize

Abstract: The study was conducted at two sites , University of Khartoum the experimental farm, faculty of Agriculture, Shambat and at west of Khartoum state, Elrawkeeb Dry Land Research Station, Sudan, during the summer and winter seasons of 2009 and 2010 respectively. Five inbred lines (2, 3, 6, 277, and 405) were used as lines and two inbred lines namely (66Y and 160) were used as (testers). These lines were crossed together according to line x tester technique to generate 10 F 1 -hybrids, every genotype was planted in rows with 4 m along, 70cm between rows and 25cm between plants. A line × tester method for estimation the general combining ability (GCA) of parent and specific combining ability (SCA) of their F 1 -hybrids was used. Genetic components resulting from additive and nonadditive type of gene action were also estimated. Heterosis was measured as a deviation from the midparents and better-parent. The analysis of variance for combining ability revealed that both GCA and SCA variances were highly significant for most of the studied characters indicating importance of additive as well as non-additive types of gene action in controlling these traits. GCA mean squares for inbred lines were significant (P < 0.01) for all the traits except cob length and number of kernels/row while GCA due to testers was only significant (P<0.05) for 100-kernels weight. Moreover, variances due to SCA were higher in magnitude than GCA for the yield and yield components except cob diameter, number of rows/cob, number of kernels/row and harvest index. GCA to SCA ratios were less than one for most of the traits except cob diameter, number of kernels row/cob, number of kernels/row and harvest index indicating a preponderance of additive over no additive gene action. High positive heterosis for grain yield and its components was found for more than half of the hybrids studied. Crosses involving 160×3 and 66Y×2 produced the highest heterosis. It can be concluded that these parental lines can be desirable parents for hybrids as well as for inclusion in breeding program, since they may contribute favorable alleles in the synthesis of new varietie

Proceedings Of The 23Rd Paediatric Rheumatology European Society Congress: Part Two

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