EFFECTS OF PRESTORAGE HYDRATION TREATMENTS ON GERMINATION PERFORMANCE, MOISTURE-CONTENT, DNA-SYNTHESIS AND CONTROLLED DETERIORATION TOLERANCE OF TOMATO (LYCOPERSICON-ESCULENTUM MILL) SEEDS

Storage of tomato seeds under deteriorating conditions reduced the rat e of germination, the uniformity of germination, total germination and the proportion of normal seedlings. Pre-storage humidification and hy dropriming of seeds resulted in a significant increase in resistance t o deterioration. In contrast, osmoprimed seeds were more deterioration sensitive. Humidification or hydropriming for one day did not allow n uclei to enter the S phase of the cell cycle. Osmopriming strongly inc reased the percentage of nuclei with replicated DNA in the embryonic r oot tip, indicating initiation of the cell cycle and progression towar ds the G2 phase. The interaction between the prestorage treatments, ce ll cycle progression and deterioration resistance, is discussed. Based on the changes in moisture content equilibrium and cell cycle activit y it is hypothesized that the beneficial effects of pre-storage humidi fication and hydropriming were related to metabolic activities induced by the partial hydration and that the adverse effects of osmopriming were caused by a decrease in DNA repair activity due to progression in the cell cycle.