A Comparison of the Effects of Acute and Protracted Gamma-radiation on the Growth of Seedlings ofVicia Faba

Publisher Website
Google Scholar
Abstract
Seedlings of Vicia faba were used to compare the effect of gamma-radiation delivered over a wide range of dose-rates. The interpretation of radiation damage would be complicated if cell-division continued during the exposure and so seedlings were stored and irradiated at 3·5°c, at which temperature root growth and cell division in the meristem is temporarily halted. The radiation damage was assessed in terms of root-growth after the seedlings had been restored to 19°c. It was found that the effect of a given dose of radiation decreased as the dose-rate was reduced from 122 rads/min to 8·4 rads/hour, and again to 1·5 rads/hour. However, subsequent lowering of the dose-rate to 0·89 rads/hour did not further decrease the effect of the radiation. It was inferred that at these very low dose-rates, the processes of radiation damage are dose-rate independent, i.e. ‘single hit’ processes.