Genetics of excised-leaf water loss and relative water content in bread wheat (Triticum aestivumL.)

Abstract

Gene effects were analyzed using mean excised-leaf water loss and relative water content of 12 populations viz., both parents (P1 and P2), F1, F2, first back cross generations (BC1 and BC2), second back cross generations (B11, B12, B21, B22) and back cross-selfed generations (B1 s and B2s) of four crosses involving three drought tolerant and three drought susceptible cultivars of Triticum aestivum L. to determine nature of gene action governing excised-leaf water loss (ELWL) and relative water content (RWC) through generation mean analysis under rainfed (E1) and irrigated (E2) environments. Both additive-dominance and digenic epistatic model were found to be inadequate in all the crosses for ELWL and in most of the crosses for RWC to explain genetic variation among the generation means. Additive gene effects were predominant for RWC, while for ELWL both additive and dominance component of variance were important. Epistatic effects, particularly dominance × dominance (1) type of interaction was more predominant for RWC, while additive × additive(i) for ELWL. Duplicate type of epistasis was observed in the crosses Hindi 62/HS240 and VL421/HS240 for RWC and in the cross S4/HPW89 for ELWL under both the environments. Complementary type of epistasis was observed only in the cross VL421/PBW175 for ELWL under E1. Hybridization systems, such as biparental mating and/or diallel selective mating could be useful for improvement of these traits which would help in isolating drought tolerant progenies.