Abstract
The biological effects of fhemecals combined with the X-rays or neutrons on rice seeds were compared with the irradiation of seeds by X-ray or thermal neutron only and the treatment of seeds by Ca(NO3)2, Colchicine, Diepoxybutane or β-propiolactone only. (c.f. Table 1, 2) Ca(NO3)2 which was used as the neutron capture, gave only a slight effect on growth and fertility of M1-plants and decreased the frequency of chlorophyll mutation in M2 generation when seeds were treated whit it just before the irradiation by neutron. Post-treatment of seeds by Colchicine increased the fertility of M1-plant compared with the single irradiation, but gave no effect on mutation frequency when combined with X-rays, and decreased the frequency when combined with neutrons. Diepoxybutane and β-propiolactone, which are already known as mutagenic substances, had high effect on germination and survival of M1-plants in both the cases ; i.e. single application of chemicals or combined with radiation. However, there increased fertility and mutation frequency treated materials when thses chemicals were used as posttreatment substances of X-rays, but there seemde no effect on mutation frequency when they were conbined with neutrons. According to this result, these mutagenic chemicals seem to have some chemical action on the process of recovering the breakage of chromosome caused by X-rays. On the other hand, no different spectra of chlorophyll mutations was obtained by a comparison of the effect of radiation alone with the effect of chemicals combined with radiation. (c. f. Table 3)
