The effect of γ-radiation including low doses on the mitotic index and root growth endpoints of Allium cepa (L.) seedlings in different intervals of the recovery time after irradiation were studied. Onion seedlings were irradiated with Cs point γ-sources of various activity, including radioactive microparticles of the Yenisei River floodplain. According to the results of 7 experiments, the inhibitory effect of γ-irradiation on onion root growth was observed in the dose range from 0.1 to 21 Gy in the time interval of the recovery period of up to 6 days, by the 10th day the damaging effect of γ-irradiation persisted mainly at absorbed doses of 5.2 Gy. A detailed examination of root growth inhibition in the time interval from 1 to 6 days of the experiment allowed us to determine that a sharp inhibition of root growth began on day 4 at absorbed doses of 2.5–10.7 Gy, and at the same time a decrease in proliferative activity in the apical meristem of the root was observed. The results of a factor analysis of the experiment on the dynamics of inhibition of primary root length and mitotic index after irradiation are presented.
Trofimova et al. (Wed,) studied this question.