Genetic analysis of agro-morphological traits in four F2 drought populations of Soybean (Glycine max Merril L.)

Abstract

Soybean is the world?s leading oilseed crop, important source of vegetable protein and demand for its seeds is increasing. Breeders have developed several widely cultivated varieties, but the genetic architecture of yield and key agronomic traits is poorly understood. In the present study, four widely cultivated soybean varieties and two exotic lines contrasting for various agro-morphological characters for crossing to develop four F2 populations viz., EC 538828 (PI 416999) x Young, JS 335 x Young, JS 95-60 x Young and JS 93-05 x JS 97-52. Significant differences are observed among the four F2 populations for all qualitative and quantitative characters under study. High coefficient of variation values was observed for many quantitative characters except for days to maturity, indicating presence of higher magnitude of variability for selection of these traits in subsequent generations for developing improved soybean cultivars. Segregation analysis of qualitative characters revealed major gene inheritance with monogenic control (for hypocotyl pigmentation, flower colour, leaf shape, pubescence, pubescence colour, pod colour, pod shattering) and digenic with various epistatic interactions (for growth habit, leaf shape, pubescence, pubescence colour, pod colour, pod shattering, seed lustre) in different crosses. Genetic control of various characters by major genes indicates scope for selection in the progenies of early generations to effectively manipulate these characters. Leaf let shape is found to be monogenic for oblong pointed being dominant over oval leaflet shape, but the ratio of 9:3:4 also observed, when lanceolate leaflet genotypes were crossed with broad leaflet shape parents in F2 population. Both 3:1 ratio and also 13:3 ratios observed for glabrous/pubescence among crosses. Pod shattering is found to be controlled by dominant inhibitory gene action.