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Screening genotypes have a crucial role to increase the efficiency of selections in plant breeding program. Therefore, this study was emphasized to determine combining ability and the association between traits among themselves and yield. The experiment was conducted at Haramaya University Research Station (Raare) for two years (2018 and 2019) using 4x7 alpha-lattice design with three replications. Pooled analysis of variance revealed highly significant (p=0.01) variations among crosses for grain yield and related traits. According to the result of combining ability analysis, parental line L3 was identified as a good general combiner for grain yield, ear diameter, 1000-kernel weight, and days to maturity. Similarly; L1, L2, and L8 proved as the best general combiner for number of kernels per row. Crosses L1×L6, L3×L5, L4×L6, L4×L8, and L5×L7 were found good specific combiners for 1000-kernel weight. Furthermore, the cross L5×L6 was the best specific combiner for ear diameter, whereas L4×L7 for both number of kernels per row and 1000-kernel weight. Likewise, the crosses L1×L5, L3×L8, L6×L7, and L7×L8 were identified as the best specific combiner towards earliness. Moreover, thousand kernel weight showed significant positive correlation with grain yield, conversely, days to anthesis, days to silking, ear aspect, and Puccinia sorghi exhibited significant negative correlation with grain yield at genotypic and phenotypic levels. Ear length, 1000-kernel weight, number of kernel rows per ear, and Turcicum leaf blight had positive direct effect on grain yield at genotypic and phenotypic level. In general, the result presented in the study might be useful for further breeding process to improve the productivity of maize. [ABSTRACT FROM AUTHOR]

Combining ability analysis for grain yield and yield component traits in maize were carried out in 8x8 diallel cross. The analysis of variance showed there is highly significant variation between the genotypes for all the traits considered. Year of testing was significant only for days to maturity and grain yield per hectare. The highest percentage of heterosis for grain over the standard varieties (BH 660) was observed by the cross L1 x L4 (29.3%) followed by crosses L1 x L5 (28.3%), L3 x L5 (21.7%) and L1 x L7 (20.8%). Mid-parent heterosis for days to maturity ranged from -2.5 to -23.9%, whereas that of better parent heterosis ranged from 0 to -13% indicating that the hybrids tend to be earlier in maturity than the parents. The mean squares due to GCA for days to maturity, ear diameter, member of kernels per row, 1000 kernel weight and grain yield were significant, indicating the importance of additive genetic variance in controlling these traits. The mean squares due to SCA were also significant for days to maturity, ear length, member of kernels per row and 1000 kernel weight indicating the importance of non-additive genetic variance in controlling these traits.The inbred lines L1, L3, and L4 were good general combiners for grain yield. [ABSTRACT FROM AUTHOR]

Abstract: Prediction of hybrid performance from inbred lines per se is crucial in targeted improvement of new traits such as stover fodder quality. The present study investigated the trend in variability and association between food and fodder traits in inbred parents and the hybrids derived from them and assessed the general combining ability (GCA) of inbred lines for both food and fodder traits. Sixteen inbred lines and sixty single cross hybrids generated by a 10×6 factorial mating design were evaluated for grain and stover yield and a range of laboratory stover fodder quality traits across three environments in Ethiopia. The hybrid and inbred line trials were planted in adjacent blocks in the same fields using an alpha lattice experimental design. Genotypes in both hybrids and inbred trials showed highly significant differences for all the traits studied. Generally, hybrids had higher grain and stover yields and lower stover fodder quality traits than the inbred lines. Both the magnitude and direction of relationship for almost all traits were similar among genotypes in the inbred and hybrid trials. General combining abilities of both lines and testers and specific combining ability (SCA) of line by tester interactions were significant for most traits studied. The highly significant GCA effects observed for most traits and the greater relative importance of GCA (lines and testers) as compared to SCA for grain yield and most stover fodder quality traits suggest the importance of additive gene effects in controlling grain and stover yield as well as stover fodder quality. Important stover fodder quality traits such as digestibility and metabolizable energy were highly heritable (h 2 =0.79–0.81) and the genotypic variations among hybrids in these traits will have implications for productivity of maize stover fed to livestock or for the income of farmers selling maize stover to fodder value chains. Significant positive relationships observed between inbred lines per se and hybrid performances for these fodder quality traits suggest the feasibility of predicting hybrid performance from the performance of the inbred lines. [Copyright &y& Elsevier]