Summarization on causes of seed dormancy and dormancy polymorphism

Causes of seed dormancy and polymorphism of dormancy were summarized in this paper. Husk obstruction, morphological embryo hypoplasia, physiological afterripping, and chemical inhibitors in seeds all induced seeds to be dormant. According to various criterions,seed dormancy could be classified into various categories, but dormancy was generally classified into exogenous, endogenous, and combinational dormancy. Causes of dormancy were complicated, and the seeds of different plant species had different characteristics of dormancy. There was variation in seed dormancy among the seeds from the same species because of various populations and individuals, periods for collecting and locations of mother plants.Moreover, there was difference among the seeds from the same fruit. Seed dormancy were generally quantitative traits influenced by a large number of genes including nuclear gene and plasmagene. The seed dormancy polymorphism benefited regulating spatiotemporal distribution of seed germination. 