| Comparison of radiation effects of beta- and gamma-rays
on Einkorn wheat S. MATSUMURA National Institute of Genetics, Misima, Japan Seeds of Triticum monococcum flavescens were soaked in 32P and 131I solutions for 2 days before sowing, to compare the radiation effects of beta-rays with those of gamma-rays. Radioactive solutions contained 0.15, 0.3 and 0.6 mc/gr of 32P and 0.6mc/gr of 131I. Also gamma-irradiation with 60Co was applied at the dosages of 2.5, 5 and 10 kr immediately after soaking the seeds in water for 2 days. The growth of seedlings, height of mature plants, single-spike fertility, and chromosome aberrations of treated plants in X1 and chlorophyll mutations in X2 were compared for beta- and gamma- irradiations. The data are shown in Table 1. The higher the dosage of beta- and gamma-rays, the more delayed were the germination and growth of seedlings and the lower were the survival rate, height of mature plants and fertility. The relation between the inhibition of seedling growth and dosage of beta- and gamma-radiations coincides roughly with that between the decrease of survival rate or fertility and dosage. There was poor germination and little growth of seedlings at 10 kr gamma-irradiation and at 0.6mc/gr 32P beta-irradiation, both irradiations being markedly effective. 5 kr gamma-rays and 0.3 mc/gr 32P beta-rays considerably inhibited the growth of seedlings and reduced the survival rate and fertility. But 2.5 kr gamma-irradiation was only slightly effective and the effects corresponded roughly to those of 0.15 mc/gr beta-radiation 32p and 0.6mc/gr 131I solutions. The frequency of ears with chromosome aberrations in X1-plants and head progenies with chlorophyll mutations in the X2-generation increased generally with the increase of beta- and gamma radiation dosage. Again the effects of 0.15 mc/gr beta-radiation 32P and 0.6mc/gr 131I solutions corresponded roughly to those of 2.5 kr gamma-radiation. These findings generally confirm the experiments performed last year. If we assume that the effects of beta-radiation are confined to the embryo, we find by calculation that the 0.15 mc/gr 32P solution equals about 2 krad. This, too, will account for the obtained data. |