Comparative effectiveness and efficiency of electron beam and ⁶⁰Co γ-rays in induction of mutations in black gram [Vigna mungo (L.) Hepper]

Dry seeds of black gram cultivar TU94-2 was treated with different doses (200, 300, 400 and 500 Gy) of electron beam and γ-rays to study the mutagenic effectiveness and efficiency on frequency and spectrum of chlorophyll and morphological mutation. A wide spectrum of chlorophyll and morphological mutations was observed in M₂ generation of γ-rays and electron beam treated population. Xantha was the most frequent chlorophyll mutant in both γ-rays (2.3%) and electron beam (4.3%) treated populations. Spectrum of morphological mutations observed were common for both γ-rays and electron beam treated populations except early seedling vigour, terminal pod bearing, three primary leaves and partial sterile mutants which were specifically observed in electron beam treated M₂ population. However, overall morphological mutation frequency was higher (9.6%) in electron beam treated population in comparison to γ-rays treated population (6.6%). Frequency of pod and root mutants were high (0.32% and 0.45%) in electron beam treated population in comparison to γ-rays treated population (0.23% and 0.35%). There was a dose dependent increase in the spectrum and frequency of chlorophyll and morphological mutations in both γ-rays (upto 400 Gy) and electron beam (upto 500 Gy) treated M₂ population. The electron beam was found to have higher effectiveness, efficiency and mutation rate than γ-rays of similar doses. Overall effectiveness was higher (0.061) in electron beam treatments when compared to γ-rays treatments (0.034). Mutation rate based on chlorophyll and morphological mutants was higher (8.3 and 2.4) in electron beam in comparison to gamma rays treated M₂ population (4.1 and 1.7). This study shows that electron beam can be used as an effective mutagen for induction of mutations in black gram.