GENETICAL ANALYSIS OF GRAIN YIELD AND SOME RELATED TRAITS IN BREAD WHEAT

Genetical analysis for grain yield and some related traits was car­ried out at Sakha Agric. Res. Sta. during 2000/2001 and 2001/2002 wheat-growing seasons. Seven diverse bread wheat cultivars namely; Sakha 61, Sakha 93, Giza 163, Giza 164, Giza 168, Gemmeiza 9 and Sids 1 were crossed in a half-diallel set to study the relative magnitude of genetic components of variation and their derived parameters. Par­ents and F₁ generations resulting from a 7 x 7 diallel mating scheme were grown in space — planted experiment in 2001/2002 season. Ana­lyzed data revealed the significant genotypic variation and validity of the basic assumptions for diallel analysis. The additive and dominance gene effects were significant and involved in the inheritance of all studied characters. Additive component played the major role in the Inheritance of days to heading, plant height and grain filling period. Thus. phenotypic selection would be an effective procedure for improving those charac­ters. Whereas, the dominance genetic variance was main component controlling the inheritance of number of kernels / spike, number of spikes/ plant, 100-kernel weight and grain filling rate. The dominance gene action was larger in its' magnitude than additive ones, resulting in (HI/D)^1/2 more than unity for all characters except for days to heading. plant height and grain filling period. The ''F" values coupled with KD/KR ratio, indicated excess of dominant increasing alleles for all characters except for plant height and number of spikes / plant. Heritability esti­mates in narrow sense were relatively high for days to heading, plant height and grain filling period; moderate for number of kernels/ spike. number of spikes / plant, grain yield and grain filling rate, while it was low for 100-kernel weight.