Studies On Seed Germination Physiological Characteristics And Methods To Break Dormancy Of Cornus Wilsoniana Wangerin

Cornus wilsoniana Wangerin is an ideal woody oil plant, however, the seeds remain dormant for 2 or 3 years in their natural environment and the germination percentage is very low. Taking Cornucs wilsoniana Wangerin seed as research material, this paper studied its basic biological characteristics, methods to break dormancy, physiological and biochemical changes during germination and dormancy mechanism. The main results were as follows:1. As reproductive units, Cornus wilsoniana Wangerin seeds were multigerm seed units, the seed coat and the endocarp of drupe closely together to form a core. Such kind of seed was spherical, the seed horizontal diameter and longitudinal diameter were respectively 0.45±0.02cm and 0.46±0.02cm, the one thousand-seed weight was 48.59±1.57g, the seed vigor by TTC method was 76% and the seed empty grain rate was 23.33%.2. We used acid (H2SO4), alkali (NaOH), oxidant (H2O2) and hormone (GA3) to treat seeds to break dormancy and speed germination. The results showed that, germinated at 25℃, the germination percentage of all treatments were very low; under conditions of indoor cold stratification, the seed germination could be promoted by the treatment of 1%H2O2 and 300mg/LGA3; but the effect is not significant.The germination percentage under conditions of indoor cold stratification was far greater than the germination percentage at 25℃.Without any reagent processing, the germination percentage under conditions of indoor cold stratification was 20%, however, the germination percentage at 25℃was almost 0, the former was 10 times the latter. Therefore, cold stratification was a simple, economical and effective approach for Cornus wilsoniana Wangerin seed. Under such conditions, for the seed germination the role of cold stratification was to increase the permeability of the seed shell and enhance the material metabolism of internal seed, so as to promote the seed germination.3. Testing storage materials contents and corresponding enzymes activities indicated that Cornus wilsoniana Wangerin seeds contained rich crude fat, its content accounted for more than 50%, seeds could be seen as oily seeds. In endosperm, during the seed germination, the contents of total soluble sugar, starch, soluble proteins and crude fat gradually degraded, while the activities of amylase, protease and ACP (acid phosphatase) gradually strengthened. The changing processes of material metabolism were consistent with the corresponding enzymes activities, they continued to provide the materials and energy for the germination of seeds.4. The result of testing water absorbing of the seed showed that, the water absorption of seed was low, only 9.44%.The endocarp was hard and dense, covered with the wax. The bioassay of the methanol extract from seed shell and endosperm indicated that, there were almost nonexistent germination inhibitory substances in the seed shell and endosperm of Cornus wilsoniana Wangerin seed. The embryo fully developed in the shape. Therefore, this study suggested that, the main causes of seed dormancy of Cornus wilsoniana Wangerin seed were the poor permeability of seed shell and the mechanical obstruction from seed shell.