Biological response, efficiency and effectiveness of gamma irradiation as mutagen on Pusa Navbahar cluster bean

Abstract

Cluster bean is a highly self- pollinated vegetable with a very narrow genetic base. Hence, mutation breeding is a viable option for generating variation. In the present study, effect of mutagen was studied in Pusa Navbahar variety of cluster bean using gamma rays from 50 Gy to 600 Gy. Preliminary evaluation at M1 generation for germination and seedling growth parameters revealed at lower doses of 100 to 200 Gy germination and growth parameters showed improvement over control. Further pollens showed steady increase in sterility with increasing dose and mutated lines showed less survivability compared to control. Thus, 100-200 Gy gamma irradiation was found useful to improve the seed germination and seedling growth parameters in cluster bean. While evaluating M2 generation, total 9 types of mutants (dark green, branched, dwarf, white flower, sterile, long pod, short pod, curve pod, small leaf) were observed and the mutation frequency was high at higher doses, whereas both mutagenic effectiveness and efficiency showed decreasing trend with increasing dose. Highest mutation effectiveness was observed at 50-100 Gy. Mutation efficiency based on pollen sterility was maximum at 50 Gy and based on lethality, it was maximum at 150 Gy.