New Method for Breaking Korean Pine Seed Dormancy

Pinus koraiensis (Korean pine) seeds possess deep dormancy caused by mechanical barrier and embryo immaturity. It usually takes 9-12 months of cold stratification to break the deep dormancy which is a main problem in nursery practice. This study was initiated to find an effective method to shorten the duration of stratification and to hasten seed germination. Thirty-one treatments were examined, focusing on the stratification period. Increased temperature in the presoaking process reduced the duration of required stratification at the low temperature and increased the rate of germination. The best method for breaking seed dormancy was pre-soaking seeds at a starting water temperature of 70°C, then at room temperature for 6 days, followed by 3 months of stratification at a constant temperature of 3°C.