The effects of radiation on pregermination plant seeds

Using pregermination plant seeds as a model for proliferative tissue, we have investigated the effects of gamma radiation and hyperthermia on barley and alfalfa. Barley seeds soaked for up to 16h prior to irradiation were given doses of gamma radiation up to 100 Gy, and alfalfa seeds soaked for up to 24h were given doses up to 500 Gy. The mean postgermination growth of barley and alfalfa seeds decreased with increasing radiation dose. The mean postgermination growth of barley and alfalfa seeds also decreased with increasing soaking time.Barley seeds soaked up to 8h prior to hyperthermic treatment were given doses of heat for up to 20$\sp\prime$ at 51.5$\sp\circ$C, and alfalfa seeds soaked for up to 24h were given doses of heat for up to 50$\sp\prime$ at 52$\sp\circ$C. The "survival" (number of shoots which were $\geq$40mm on day 8 for barley, day 5 for alfalfa) and mean number of seeds germinated per plate decreased with increasing heat duration. The "survival" of both barley and alfalfa seeds decreased with increasing soaking time.Although barley seeds were up to approximately an order of magnitude more radiosensitive than alfalfa seeds, both seed species had comparable heat sensitivities. The difference in the responses of barley and alfalfa to radiation and heat suggest different mechanisms and/or targets for radiation and heat damage.Modifiers of radiation and heat effects were also studied. DMSO and glycerol had a radioprotective effect on barley seeds, and conferred a near-maximal amount of protection at a concentration of 1.4M. In addition to its radioprotective effect, glycerol provides protection to barley seeds against heat. Ethanol was found to sensitize barley seeds to heat. Barley seeds irradiated with 100% oxygen bubbling through the irradiation liquid have a lower mean postgermination growth than seeds irradiated in room air.U of I OnlyETDs are only available to UIUC Users without author permissio