Abstract: Effects of gibberellic acid (GA₃) and chilling treatments on releasing epicotyle and radicle dormancy and promoting seedling growth were studied in Paeonia ostii 'Feng Dan' to improve the protocol of seedling reproduction. Results showed that GA₃ treatments with lower concentration （100～200 mg﹒L^-1）enhanced the quality of rooting. In a certain range, extending the duration of chilling promoted epicotyle dormancy release and seedling growth and a proper concentration GA₃ promoted seedling growth and total biomass accumulation, but, when the chilling days were long enough to releasing epicotyle dormancy, a higher concentration of GA₃ was not beneficial to the growth. Comprehensive analysis on the effects of various treatments on shoot germination rate, germination index, seedling height, the first leaf width, leaf number, shoot length, shoot and root dry mass within 100 days after seeds were treated suggested that 21 and 28 days chilling combined respectively with 100 mg﹒L^-1 or 200 mg﹒L^-1 GA3 were beneficial to both seed germination and seedling growth, which could be extended into the seedling production of 'Feng Dan'.

Key words: Paeonia ostii, seed, epicotyle dormancy, chilling, gibberellic acids