| Effects of temperature on postirradiation storage in
einkorn wheat Tomoo MABUCHI National Institute of Genetics, Misima, Japan It is well known that post-irradiation storage increases radiation damage in X- or gamma-irradiated seeds, especially in super dry seeds (4-8 %). Recently, MATSUMURA et al. (1961) reported that chronic irradiation was more effective in producing radiation damage than actue treatment in dry seeds of upland rice. However, they could not find such a relationship in seeds of einkorn wheat. An experiment was carried out to test whether or not a storage effect exists during chronic irradiation of seeds of einkorn wheat. Dry seeds of einkorn wheat were irradiated with 10 and 15 kr gamma-rays at acute dose rate of 10 kr/hr and stored in constant temperatures of 0C, 13C and 30C for 436 hours. Furthermore, some of the treated seeds with 15 kr were also preserved at 13C for 138 and 700 hours. All treated seeds were sown almost simultaneously, just after storage. The data for seedling height and seed fertility in the X1-generation are shown in the table. There was found a slight radiation damage in acute 10 kr irradiation. The seedling height and seed fertility were significantly reduced with prolongation of storage, when the irradiated seeds were stored at 13C after 15 kr irradiation. The results show that there was a clear storage effect. There was also a clear storage effect on seedling growth and seed fertility of gamma-irradiated seeds, stored at 13C and 30C for 436 hours after 15 kr irradiation but no clear storage effect was found in seeds, stored at 0C for 436 hours. The results of this experiment show that storage effect was greatly influenced by irradiation dose, temperature and storage duration. It is therefore considered that storage effect is noticeable if seeds are irradiated chronically, but the effect may be often masked due to modifying factors i.e. temperature or water content. |