21230

査読無

0368-6264

AN0005519X

1. Effects of fast neutrons upon the seeds of Pinus densiflora appeared not only in the germinative capacity, but also in the survival rate and the growth of the seedling. 2. By exposing seeds to irradiation of neutron rays, an appreciable retardation has been noticed in the germination of them. 3. The percentages of germinations, the survival rates were higher, and the growth of seedlings were found to be better in the classes exposed to the neutron rays at certain doses than in the control. 4. Exceeding the limits, the percentages of germinations, the survival rates and the growth of seedlings were inverse proportional to the doses of radiations. The survival rates results in zero when the intensities of irradiations being medium for 120 min. (B-120), strong treatment for 60 min. (C-60) and over (intensity, 600 arbitrary units and over). 5. The susceptibility of the pine seed to neutr on radiations is higher in the soaked one immersed in tap water for 1 or 3 days, than in the dry. This work was carried out according to the programm of the Atomic Neucleus Sub-Committee of the Japan Society for the promotion of Scientific Research to which we wish to express our gratitude. We acknowledge the kind assistances given by Mr. K. Murati and Mr. J. Ozawa during the cource of this study.