Effect of Short-Term Heating Pretreatment on Germination of Pinus yunnanensis Seeds

In order to explore the possibility of Pinus yunnanensis seed germination after a middle and lower strength fire, and the effect of fire on seeds, the P. yunnanensis seeds were subjected to three heat treatments (60℃, 90℃ and 110℃ separately) for 1min, 5min and 15min, together with a group of seeds treated under 20℃ as control. The differences in seed germination rate, the activities of antioxidant enzyme of superoxide dismutase (SOD), peroxidease (POD), catalase (CAT) of the seeds with different treatments were determined, and the correlations of the germination rate with SOD, POD, and CAT activities were studied. The results showed that 1min and 5min pretreatment of the seeds under 60℃ could promote the germination rate, indicating that there was a thermal shock effect on the P. yunnanensis seeds. The germination rate still reached 36%±3% after the treatment at 110℃ high temperature for 15min, showing that to some extent, P. yunnanensis seeds had a good resistance on high temperature. The results also showed that SOD, POD and CAT activities were extremely significantly and positively correlated with germination rate of P. yunnanensis seeds, the generation of thermal shock effect was closely related to SOD, POD, CAT activities.