Theoretical growth-rate curves for Vicia faba roots under continuous radiation exposure at low dose-rate: a comparison with experimental results.

Abstract

SummaryUsing models for the meristem of Vici faba proposed previously, theoretical curves of growth-rate have been computed for conditions of continuous radiation exposure at low dose-rate (1–10 rads/hr). These have been compared with experimental results. The best agreement is obtained assuming cell death at the second division following radiation damage, allowing for some gradual increase in cell cycle time during irradiation and postulating that, at any rate at the lower dose-rates, sterilised cells differentiate and contribute to root elongation. The match between theoretical and experimental curves suggests a value for D0 of about 240 rads for the ‘single hit’ type of mechanism assumed to apply at these dose-rates. It is predicted that if the cell-cycle time is varied, similar growth-rate curves should be observed for the same dose received per cell cycle (rather than for the same dose-rate).