Modification of Radiation Damage in Dormant Seeds by Storage

Abstract

Dormant seeds of barley were exposed to different doses of X-rays, gamma rays or fast neutrons and stored for varying times following the treatments. Following storage, the seeds were germinated and grown on moist blotters. Radiation damage was measured as percent reduction inseedling height from the control at 6 days. It was found that damage increase by a factor of 20 after storage for a few weeks. There were two components to the curve of storage versus damage. The 1st component was rapid and nearly complete in 4 hours, while the 2d 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 1st component to the curve, while for moist seeds the 1st component was very small or absent. The 2d component was approximately the same for dry and moist seeds. There was no storage effect found for seeds irradiated with fast neutrons. No clear explanation for these results can be presented at present, but they are very similar to results which have been obtained as an "after effect" of radiation in certain aqueous solutions.