Inheritance Pattern of Metric Characters Affecting Grain Yield in Two Bread Wheat (Triticum aestivum L.) Crosses Under Rainfed Conditions

The present investigation was undertaken to study the inheritance pattern and genetic analysis of some indicators of grain yield in F_1 and F_2 populations of two bread wheat crosses. The results reflected a satisfactory range of variability within and among the studied generations. Significant positive selection differentials were observed for all characters. High heritability estimates, coupled with high to moderate expected response to selection, were observed in most traits. High predicted genetic gain was observed for grain yield and above ground biomass. The estimated number of genes, involved in the genetic control of these characteristics, varied between 2 to 5, showing partial to over-dominance, suggesting that the selection must therefore be delayed until the F_4 or F_5 generation. Significant heterotic values in positive direction were found for all characters except thousand-kernel weight in both crosses and number of grains per spike in Acsad_899 × Mahon-Demias cross. Inbreeding depression was observed in both crosses for the number of spikes, above-ground biomass and grain yield. The obtained results indicated that the studied crosses would be of interest in the breeding program. It was suggested that the selection for all characters, except for thousand-kernel weight, should be effective in early segregating generations due to additive gene effects.