Caused of Seed Dormancy and Dormancy Breaking of Michelia sphaerantha

Michelia sphaerantha is a rare ornamental tree species distributed in Yunnan province characterized by seed dormancy.In order to promote the propagation of M.sphaerantha,the causes of seed dormancy and the methods for breaking dormancy were studied from the morphological structure,the water permeability of seed coat,inhibitory substances in seed,seed vitality determination and seed germination test.The study results showed that incomplete development of embryos and inhibitory substance in seed were two main reasons for seed dormancy.The water permeability of M.sphaerantha is good,implied the low correlation with seed dormancy.It was therefore conclude that the seed dormancy of M.sphaerantha is morphological and physiological dormancy.Soaking seeds with distilled water or gibberellic acid solution could effectively break the dormancy of M.sphaerantha seeds.