Genetical analysis of some quantitative traits in wheat using six parameters genetic model.

摘要

The assessment of gene effect for some yield traits and detection of epistasis in wheat was studied in three crosses namely Gemmeiza 10 x Sakha 94 (cross I), Gemmeiza 9 x Sids 4 (cross II) and Gemmeiza 9 x Gemmeiza 10 (cross III) involving four parents through generation mean analysis during 2010/2011 season at the Experimental Farm of the Agronomy Department, Faculty of Agriculture, Al-Azhar University, Cairo, Egypt. The analysis of gene effects was done using means of six populations, P₁, P₂, F₁, F₂, BC₁ and BC₂ of the three crosses. The mean value of F₁ population was higher than the respective parents (P₁ and P₁), F₂, BC₁ and BC₂ populations for most the studied traits in the three crosses. Heterosis in F₁ crosses over their respective mid 1 and better parents for grain yield ranged from 28.15 to 50.14% and -5.38 to 42.07%, respectively. Significant positive values of inbreeding depression were detected for all studied traits in the three crosses, except spike length and number of spikelets/spike in the third cross as well as 100-grain weight in the first and the second crosses. The highest values of phenotypic and genotypic coefficient of variations were obtained for number of spikes/plant, grain weight/spike and grain yield/plant. While, the lowest one was recorded for number of grains/spike. The coincidence of sign and magnitude of heterosis and inbreeding depression was detected for most traits in the three wheat crosses. Dominance gene effects were positive and significant for most of the studied traits in the three crosses, whereas additive gene effects were not significant except number of spikelets/spike, number of grains/spike and grain yield/plant in the cross III and number of grains/spike in the cross I. However, the dominance gene effects were more important than additive gene effects in the inheritance of grain yield and most of the other studied traits. The magnitude of additive x additive gene effects was high and positive significant whereas dominance x dominance was negative significant for most of the studied traits in the three crosses. Additive x dominance gene effects were of minor importance in general for most of the studied traits. It could be concluded that selection for grain yield and its components should be delayed to later generations in breeding programs.