Influence of Environmental Factors on Seed Germination and Seedling Formation of Primula filchnerae

Primula filchnerae,which disappeared more than one hundred years ago and was assumed extinct,was rediscovered in 2006 in Zhuxi and Zhushan County,Hubei Province,China.Studies on seed germination and seedling formation of P.filchnerae will contribute to the protection of the species and its landscape development.Seeds of P.filchnerae were small and the thousand seed weight was 0.90±0.12 g.We determined 25℃,2700 lx and fresh seeds as the optimum condition for seed germination.The seedling rate,however,was only about 25% and the seedling germination ratio was significantly lower than other conditions.Seed dormancy occurred at 29℃;however 200 mg/L gibberellins(GA₃) treatment significantly increased the germination rate,decreased the time to start germination,seedling rate and seedling germination ratio.After more than two months of high temperature and high humidity(29℃ germination condition) treatment,the germination rate of all un-germinated seeds remained unchanged but the time to start germination decreased significantly when they were transferred to 25℃.These results showed that dormancy at high temperature followed by soaking with 20 mg/L GA₃ before seed germination,significantly increased the germination rate,seedling rate and seedling germination ratio of P.filchnerae.