Useful heterosis and combining ability for grain yield and resistance to downy mildew disease (Prenosclerospora sorghi) in some new yellow inbred LI NES of maize [electronic resource].

Includes references.

Sixteen new inbred lines of yellow maize with wide genetic diversity were top-crossed with two narrow and one broad genetic testers to obtain 48 top-crosses in 2002 growing season. These crosses and two commercial check hybrids were evaluated at two locations Sakha and Nubaria Agriculture Research Station to estimate combining ability and useful heterotic effects for grain yield, its components and percentage of resistance to downy mildew disease (DMR%) in 2003 season. The obtained results revealed that, additive genetic variance (σ2 GCA) was more important than non-additive genetic variance (σ2 SCA) in the inheritance of days to 50% silking, ear position, No: of kernels/row, 100-kernel weight, grain yield ard/fed and DMR%. Meanwhile, σ2 SCA played an effective role in the expression of plant height, ear height, ear length, ear diameter and grain yield/plant. The magnitude of the interaction of σ2 SCA by locations «(σ2 SCAxLoc.) was markedly higher than those of (σ2 GCAxLoc. for ear length, ear diameter, kemels/row,100-kernel weight, grain yield ard/fed and grain yield/plant. While, (σ2 GCA was more sensitive to environmental conditions than (σ2 SCA for days to 50% silking, plant height, ear height, ear position and rows/ear. Inbred lines Sk-700817 and Sk-7008/12 exhibited good general combiners for grain yield and DMR%. Also, inbred line Skug-IO was the best combiner for earliness, ear position, grain yield and its related traits. Nine inbred lines are found desirable and inherited favorable alleles of DMR% in their top-cross progenies.

Summary in Arabic.

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