Abstract
Seed of the OAC Rico and Swan Valley cultivars of bean (Phaseolus vulgaris L.) was treated with 0.04 M ethyl-methane sulphonate (EMS). Screening of M2 populations in the presence of 8 mM nitrate + 2 mM ammonium, which substantially inhibited nodulation of the parental cultivars revealed nitrate tolerant supernodulating (ntsn), copious nodulating and non-nodulating mutants. One ntsn mutant from 175 M1 lines of OAC Rico and two ntsn mutants from 467 M1 lines of Swan Valley were obtained. M3 progenies derived from the Rico and the one fertile Swan Valley ntsn-mutants (M2) bred true.Key words: Nodulation, dry edible (navy, common) bean, EMS, Phaseolus vulgaris