Estimation of epistasis, additive and dominance variation in some bread wheat (Triticum aestivum, L) crosses [electronic resource].

Includes references.

A. 8 and C scaling test as well as 6-parameters model were used in order to assess the nature of gene effects for seven traits in three crosses of bread wheat viz. plant height, number of days to heading, number of days to maturity, number of spikes/plant, number of kernels /spike, 1000 kernel weight and grain yield /plant in three bread wheat crosses (Triticum aestivum, L). Analysis of variance indicated significant differences existed among generations for all studied traits. Non-allelic interactions were observed for all traits and crosses except in few cases in which the values did not reach the significant levels. In the 6-parameters model, the additive component (a) as well as dominance component (d) were significant in most cases. Additive X additive (aa) was significant for all cases except for plant height in cross III. Additive X dominance (ad) component was significant for plant height in cross II and days to maturity and spikes/plant in cross 1. The dominance X dominance (dd) component was significant for all cases except for days to maturity in cross II, and spikes/plant in cross I and cross III. Significant values of heterosis based on mid- parent values were obtained. Negative Inbreeding depression was detected for some traits in some crosses whereas no inbreeding depression was observed for spikes/plant in cross I. High heritability values in broad sense were observed for all studied traits for all crosses. Narrow sense heritability ranged from 42.05 for kernels/spike to 74.30 for plant height in cross III. Genetic advance values were higher for spikes/plant in all crosses whereas those values were found to be very low for days to maturity in all crosses under study.

Summary in Arabic.

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