Study of micronucleus induction in the root-tip cells of onion seedlings after irradiation as dry dormant seeds by 252Cf fission neutrons

The work is for a better understanding of relative biological effectiveness (RBE) of 252Cf fission neutrons. The frequency of micronuclei induced in the root-tip cells of onion seedlings after irradiation as dry dormant seeds by unit dose of 252Cf neutron-γ mixed irradiation is different from that by 60Co γ-ray irradiation. The frequency of micronuclei induced by unit dose of 252Cf neutron-γ mixed irradiation and 60Co γ-ray irradiation are 1.84 ± 0.10 and 0.022 ± 0.002 (%Gy-1), respectively; and the frequency of micronuclei induced by unit dose of 252Cf fission neutrons is 2.74 ± 0.15 (%Gy-1). The RBE values for 252Cf neutron-γ mixed irradiation and 252Cf fission neutrons are 84 ± 9 and 124 ± 13, respectively. The frequency of micronuclei induced in the root-tip cells of Allium cepa onion seedlings irradiated as dry dormant seeds by unit dose of 252Cf neutron-γ mixed irradiation is about 84 times as that by 60Co γ-ray irradiation. The findings suggested that repair efficiency of DNA damage induced by neutrons might be different from that by γ-ray. (authors)