Differences in radiosensitivity and mutation induction in lentil due to variation in the genotype and the type and dose of mutagen

Seeds of the macrosperma (bold seeded Acc. L-162 and the microsperma (small seeded Acc. L-112 of lentil were treated with various doses of gamma rays and combinations of gamma ray + sodium azide concentrations. Germination and survival decreased with the increase in radiation dose in the two strains, but the decrease was more pronounced in the macrosperma type. The same trend of reduced germination and survival was also observed in both types with the increased doses of the combined treatments. However, the reductions were more drastic in the combined treatments than in the sole gamma ray treatments. The macrosperma type was therefore more radiosensitive. The seeds of all the surviving M1 plants were sown as M2 and 70 deviants were selected from the microsperma type and 30 from the macrosperma type on the basis of the increased number of pods and secondary branches per plant. In the M3 generation, a higher number of true breeding progeny lines was identified from the macrosperma type than the microsperma type. In the macrosperma genotype, more mutants were isolated from sole radiation than the combined treatments. The spectrum of mutation in the microsperma genotype showed a reverse trend. Sole radiation yielded fewer mutants than the combined treatments. It was therefore concluded that the mutation spectrum in the lentil depends greatly on the genotype and the type and dose of mutagen used. The selected mutant lines have shown promise of an increased number of pods per plant and a higher seed yield than their respective parents. (author). 8 refs, 3 tabs