Studies On Dormancy Mechanism Of Macrocarpium Officinale Seeds

The causes of seed dormancy of Macrocarpium officinale were discussed, by measuring the testa structure and permeability, the embryo excision test together with the bioassay of extracts from different parts of seeds. The seeds also treated by soaking with hormone solutions and stratification in different temperatures to find out the method for breaking seed dormancy. To further reveal the seed dormancy mechanism, the hormone contents, nutriments content and enzymes activities were also determined. The results were as follows:1. The permeability of testa was poor and its mechanical hinder also was hard, which were the main causes of seed dormancy. The germination of seed embryos proved that the embryo was not dormant itself. The measuration of endogenic inhibitors showed that the extracts of epicarp and testa strong inhibited the growth of cabbage seedlings. The extract of epicarp and testa strongly inhibited the germination of cabbage seeds.2. The extraction phases of epicarp and testa were obtained by using the systematical solvent separation method. The phases of acetic acid and methanol of epicarp and testa had strong inhibition effects to the germination of cabbage seeds , height growth and the root length growth of cabbage seedlings.3. The nutriment metabolism gradually strengthened during stratification, as the lipid and starch descended as a whole and the activities of relative enzymes was also ascended. The protein and saccharide were gradually transformed and utilized, indicating seed metabolism was strengthened.4. The contents of endogenic hormones were fluctuated: the GA3 content ascended as a whole, the ABA content descended, the IAA and ZR content changed complicatedly.5. The seed germination percentage could be greatly ascended after alternative stratification and cold stratification lasting for certain time period. Soaking with the GA solution could enhance the germination percentage before stratification. Acid scarification was not effective to the testa structure, and the seeds would rotten a great deal during stratification if treating time was not properly controlled.