| I. Research Notes Radiation effects of beta- and gamma-rays in Triticum monococcum S. MATSUMURA National Institute of Genetics, Misima, Japan Dormant seeds of Triticum monococcum flavescens were soaked in water or 32P and 131I solutions for 1 and 2 days just before sowing. Radioactive solutions contained 0.2-1.2 mc/gr of 32P and 0.8-1.6mc/gr of 131I. To compare the beta-radiation effects of these solutions with those of gamma-rays, the seeds were subjected to chronic gamma-radiation from a 60Co source at 2, 4 and 6 kr during water-soaking. The germination rate, seedling height 4 weeks after sowing, survival rate, mature plant height, seed fertility and chromosome aberrations in PMC's of the treated plants, and the chlorophyll mutations in the X2 were compared. As to the first 5 characters, the effects of beta-radiation from 0.2 mc/gr 32P solution for 2 days corresponded roughly to those of 4 kr gamma-radiation for 2 days, and were slightly higher than those of 1 day beta-radiation from 0.4mc/gr 32P solution and of 1 day gamma-radiation at 4 kr. Also the effects of 1 day beta-radiation from 0.8mc/gr 32P solution coincided roughly with those of 6 kr gamma-radiation for 1 day. Further one day beta-radiation from 1.6mc/gr 131I solution for 1 day was considerably less effective than 2 kr gamma-radiation for 1 day and showed similar effects as 1 day beta-radiation from 0.2 mc/gr 32P solution. In general, the effects of gamma-radiations on chromosome aberrations and gene mutations were unexpectedly small, compared with those of corresponding beta-radiations from 32P and 131I solutions. If we assume that the effects of beta-radiation are confined to the embryo, we find by calculation that the 0.4mc/gr 32P solution for 1 day or the 0.2mc/gr 32P for 2 days equals 5 or 4.8 krad, respectively. This, too, will account for the obtained data. |