The Preventive Effect of PEG Treatment on Thermal Dormancy of Pyrus ussuriensis Seeds

To investigate the effects of PEG priming and osmotic treatment on the induction of the germination indicators and endogenous hormone content of Pyrus ussuriensis seeds, the primary dormancy released seeds of P. ussuriensis was used as experimental materials, the germination performance of P. ussuriensis seeds treated with different mass fractions(5%, 25%, 50%) of polyethylene glycol(PEG) solution for different durations(0.5, 1, 2 d) or osmotic treatment for different durations(1, 3, 7 d) at high temperature(25 ℃) was studied then select treatments with significant effects to measure changes in endogenous hormones in seeds. The results showed that both 25% PEG priming and osmotic treatment for 1 day could effectively weaken the induction of thermal dormancy in P. ussuriensis, achieving a preventive effect. The effect of PEG priming treatment on reducing seed thermal dormancy is better than that of osmotic treatment. When treated with 25% PEG solution for 1 day, the germination rate of seeds was increased by 57%, the germination index was increased by 0.65, and the average germination time was shortened by 7.88 d. PEG priming can prevent P. ussuriensis seeds from entering thermal dormancy by increasing the endogenous ETH and GA₃ content in the early germination stage and reducing ABA content.