Gene action of some seedling traits associated with drought tolerance in bread wheat [Triticum aestivum L.]
2005
Kumar, A. | Sharma, S.C.
An investigation was undertaken to understand the nature of gene effects for coleoptile length, root and shoot length and seedling vigour index in bread wheat. For this study, twelve generations viz., P1, P2, F1, F2, BC1, BC2. B11, BI2, B2I, B22, B1s and B2s of four drought tolerant x susceptible crosses viz., S4 x HPW89, Hindi 62 x HS240, VL421 x HS240 and VL421 x PBW175 were used for generation mean analysis in both moisture stress (E1) and moisture non-stress (E2) environments, separately. Additive dominance model was found to be adequate only in the cross VL421/HS240 for coleoptile length under E2. Digenic epistatic model showed its adequacy in the cross S4/HPW89 for root length and in the cross Hindi 62/HS240 for shoot length under both the environments and, beside this, in the cross S4/HPW89 for seedling vigour index under E2 and in the cross VL421/HS240 for coleoptile length under EI. Gene action studies indicated that coleoptile length and shoot length were predominantly governed by additive genetic effects and there is equal importance of both additive and dominance genetic effects for root length and seedling vigour index with the involvement of epistatic effects, particularly dominance x dominance interaction, for all the traits. Duplicate epistasis was also observed for coleoptile length in the cross S4/HPW89, for shoot length in the cross VL421/PBW 175 and for SVI in the crosses S4/HPW89 and Hindi/HS240 under both the environments. Significantly positive heterosis was observed over both BP and SC in the crosses VL421/HS240 and VL421/PBW175 for root length under moisture stress environment. Genotype-environmental interactions and/or differential gene expression appeared to account for different results found between environments. Hybridization systems, such as biparental mating and/or diallel selective mating, could be useful for improvement of these traits which could help in isolating drought tolerant progenies
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