Gene system governing stomatal number and specific leaf weight in bread wheat ( Triticum aestivum L.)

Abstract

Gene effects were analysed using mean stomatal number and specific leaf weight of 12 populations, consisting of both parents (P 1 and P 2 ), F 1 , F 2 , first backcross generations (BC 1 and BC 2 ), second backcross generations (B 11 , B 12 , B 21 , B 22 ) and backcross selfed generations (B 1 s and B 2 s) of four crosses involving three drought-tolerant and three drought-susceptible cultivars of Triticum aestivum L. to determine the nature of gene action governing stomatal number (SN) and specific leaf weight (SLW) through generation mean analysis in moisture stress (E 1 ) and moisture non-stress (E 2 ) environments. The digenic epistatic model was found to be inadequate for stomatal number and the additive-dominance model was found to be adequate for specific leaf weight in most of the crosses. Additive gene effects were predominant for SLW, while for SN both additive and dominance components of variance were important. Epistatic effects, particularly the additive × dominance (j) type of interaction, were present for both the characters. The duplicate type of epistasis was observed for stomatal number in the cross VL421/HS240 in the moisture stress environment. Significant heterosis was observed for the crosses Hindi 62/HS240 and VL421/HS240 over the standard check (SC) in the moisture stress environment (E 1 ) for both the characters. Genotype-environmental interactions and/or differential gene expression appeared to account for the different results found between environments. Hybridization systems, such as biparental mating and/or diallel selective mating, could be useful for the improvement of these traits, which would help in identifying drought-tolerant progenies.