Effect Of Heat Stress On Physiology Metabolism And Aging Of Rape Oat And Soybean Seeds

Under heat stress gradient, the seeds of rape(Brassica campestris L.), oat(Avena sativa L.) and soybean(Glycine max (L.) Merr.) were compared in aspects of germination ratio, germination index, the seed vigor index, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity, malondialdehyde (MDA) content, seed leaching of soluble sugar content, relative electrical conductivity, and Maillard reaction products in seeds. The main research results were as follows:1. As treating temperature rising, the germinate rate, germinate index, SOD activity, POD activity, CAT activity of seeds decreased. While the MDA content, soluble sugar content, electric conductivity, content of Maillard reaction product of seeds rised. After 90℃treatment for twelve hours, the germinate rate of rape seed is 96.60%, the germinate rate of oat seed is 41.68% and the soybean seed didn't germinate at all. This implies that fat seed is of higher capacity of heat resistance. Next is starch seed. The capacity of enduring heat stress of protein seed is the weakest.2. There was positive correlation between SOD activity, POD activity, CAT activity, MDA content, soluble sugar content, electric conductivity and seed vigar of three seeds. The order of positive correlation degree is protein seed, fat seed, and starch seed.3. As temperature rising, there was negative correlation between the content of Maillard reaction product and seed vigar of three seeds. Correlation coefficience is -0.928(rape), -0.947(oat), -0.936(soybean). It is proved that production of Maillard reaction product can make seed aging quickly.4. POD activity, SOD activity, CAT activity, MDA content, soluble sugar content of seedling are consistent with those of seeds. Effect of heat sress on seed can be transfered plant growing stage.