Determination of gene action for yield and its related traits in soybean under North-Western Himalayas conditions of India

ABSTRACT

Aim: To understand the nature and magnitude of gene action for yield and its related traits in soybean.Methodology: Fifty four triple test cross progenies developed by crossing 18 lines with three testers Him soya and Hara soya (P1 and P2) and their F1s were used as testers ‘L1’,’L2’ and ‘L3’. F1 seeds were produced by crossing Him soya with Hara soya during kharif 2011. By crossing these three testers with 18 lines (females), 54 triple test cross hybrids were developed during kharif 2012. The fifty four F1 hybrids along with 18 lines and 3 testers were sown during kharif 2013 in a randomized block design with three replications. Results: In the triple test cross progenies, sufficient genetic variations were found for all the traits, except petiole length. Epistasis was observed to be an integral part of genetic variations for traits like plant height, branches per plant, nodes on main stem, internode length, pods per plant, pod length, biological yield per plant, seed yield per plant, oil content, crude protein content. Epistatic interaction for most traits was additive x dominance and dominance x dominance (j+l) type. In addition to additive x dominance and dominance x dominance (j+l), additive x additive (i) type epistasis was observed for plant height, internode length, pods per plant and biological yield per plant. For the inheritance of most traits, fixable type of gene action was found as additive component (D), was more pronounced than dominance component (H), except pod length. Interpretation: For improvement of traits, selection in the early generations will be useful as additive gene action was observed. The importance of additive x dominance (j) and dominance x dominance (l) type of epistasis in the inheritance of seed yield and other related traits signifying the importance of recurrent selection in order to develop high yielding varieties. For pod length, both additive and dominant components were observed. Thus genetic improvement in seed yield would be easier through indirect selection for pod length.