Radiation Studies in Lens Culinaris*

Radiosensitivity as reflected by germination percentages was unaffected at 4 and 8 kr in both varieties of Lens culinaris. The percentage of germination was affected markedly at 12, 16, 20, 24, 28 and 32 kr in both varieties. In variety macrosperma ii ranged from 88% at 12 kr to 11% at 32 kr and in variety microsperma it varied from 95% at 12 kr to 27% at 32 kr. The percentage of survival at maturity remained unaffected at 4 and 8 kr in both varieties, but in variety macrosperma it ranged from 82% at 12 kr to 30% at 32 kr. Whereas, in variety microsperma ii varied from 92% at 12 kr to 12% at 32 kr. In both varieties the controls showed approximately 98% of germination and survival at maturity.

There was an apparent stimulation in the growth of root and shoot at 4 and 8 kr in both varieties. At the doses of 12, 16 and 20 kr the retarding effect of radiation on growth of root and shoot was visible in both varieties. The effect of both stimulation and retardation was more marked in variety macrosperma than microsperma. Roots appeared to have suffered more than shoots in both varieties.

The effects of irradiation on plant attributes were recorded at doses of 4, 8, 12, 16 and 20 kr in three successive generations. The plant attributes taken into consideration were plant height, number of primary branches, number of flowers, number of pods and number of seeds set per plant. It was found that genetic variability and sterility increases with dose in M₁ generation. The plants showed stimulation in their morphological developments (greater height, more branches etc.) at 4 and 8 kr, whereas, at 12, 16 and 20 kr, there was an inhibitory effect in M₁ generation. The capacity to set seeds appeared to have decreased with the increase of dose in both varieties. In the M₂ and M₃ generations the plants showed a definite tendency to return to normality.

From the results it appeared that the variety macrosperma ii more radiosensitive than variety microsperma, at all the above doses.