Modification of Radiation Damage in Dormant Seeds by Storage

Dormant seeds of barley were exposed to different doses of x rays, gamma rays, or fast neutrons and stored for varying times after the treatment. After storage, the seeds were germinated and grown on moist blotters. Radiation damage was measured as per cent reduction in seedling height from the control at 6 days. It was found that damage increased by as much as a factor of 20 after storage for a few weeks. There were two components to the curve of storage versus damage. The first component was rapid and nearly complete in 4 hours, whereas the second component was very slow and lasted many weeks. The moisture content of the seeds greatly influenced the magnitude of the effect and the nature of the curves obtained. Very dry seeds showed a large first component to the curve, whereas for moist seeds the first component was very small or absent. The second component was approximately the same for dry and moist seeds. There was no storage effect for seeds irradiated with fast neutrons. No clear explanation for these results can be given at the present time, but they are very similar to results which have been obtained on an after-effect ofmore » radiation in certain aqueous solutions. (auth)« less