Abstract: Ostrya rehderiana is a critically endangered plant species with only five natural individuals remaining in Tianmu Mountain, Zhejiang Province, China. To explore the seed dormancy and germination of O. rehderiana, the seeds were collected from the natural individuals in November 2008 and 2009 and manipulated in illumination incubator in different treatments. Results showed that these seeds have a water absorption rate of 20% after immerging in water for 4 h (p<0.05), indicating it was not physical dormancy (PY). The seeds have higher cumulative germination rates after short low temperature storage (4 weeks v.s. 16 weeks; p<0.05), suggesting low temperature might induce seeds dormancy of O. rehderiana. To break dormancy, relative longer times (median length of germination time=54 d) of temperature above 15 ℃ were needed, indicating the seeds may belong to physiological dormancy (PD). The most favorable germination condition was 15/25 ℃ employing 400 or 600 mg·L^-1 GA. We conclude that seeds treated with GA should be sown in a fitting condition immediately to germinate well in the ex situ conservation of O. rehderiana. In addition, it is a feasible method that seeds germinate in the nature with added GA artificially.

Key words: Ostrya rehderiana, seed dormancy, germination rate, temperature, gibberellin (GA)