Comparative mutagenic effectiveness and efficiency of physical and chemical mutagen and induced variability in ricebean (Vigna umbellata Thunb, Ohwi and Ohashi)

Healthy and pure seeds of two varieties of ricebean viz., BRS-1 and Totru Local were treated with gamma rays (30, 40 and 50 kR) and ethyl methane sulphonate (EMS) (0.50, 0.60 and 0.70%). A steady reduction in germination and subsequent survival of the treated population and seedling height reduction was observed with the increasing dose/concentration of mutagens in both the cultivars regardless of the mutagens used. EMS was almost four times more effective and two times more efficient than gamma-rays and both mutagenic effectiveness and efficiency decreased with an increasing doses/concentrations of mutagens. The coefficient of variation for all the quantitative characters were of higher magnitude compared to control in both the cultivars. The lower doses (30kR in gamma rays and 0.50% in EMS) were found to be the most important doses for inducing desirable variability in ricebean and two traits i.e. pods per cluster and seeds per pod showed high heritability coupled with high genetic advance in both BRS-1 and Totru Local indicating that breeding for these traits can be achieved by phenotypic selection.