Studies On The Relationship Of Substance Metabolism And Dormancy Releasing Of Sinojackia Xylocarpa Seeds

Seeds longevity of S.xylocarpa in soil seed bank and metabolic of endosperm in process of natural stratification were studied in this paper, the results showed that:1,The safety moisture content for S.xylocarpa seed storage was 7.5%. In soil seed bank,the seed viability reduced to 38% after 10 months on the surface of the ground;the seed viability was 60% after 12 months covered with the leaves and still as high as 75% after 17 months buried in soil at the depth of 5 cm and 10 cm.2,Seed dormancy can be released after 15 months in natural stratification. During the process of natural stratification, the TEM of endocarp and the SEM of endosperm showed that: the shell is mainly formed by the sclerenchyma, sclerenchyma was strongly thickened, and arrayed densely. Little change took place in the shell during the former 12-month natural stratification. After 15 months, the seeds with rotten shell began to germinate. The seed endosperm contains a large number of high-electro-dense material and lipid, high electro-dense material has been gradually degraded during stratification.3,During the process of natural stratification, the starch and fat contents of endosperm reduced gradually, but the fat degraded mainly in the last month of the cold stratification; protein content increased gradually at the beginning of 12 months during natural stratification, but declined rapidly in the last three months of stratification. The activity of amylase, protease and acid phosphatase was lower in the former 12-month stratification, but its activities increased rapidly during the last three months of cold stratification. When the seeds had been stratificated for 14 months, TCA and EMP pathway were activated firstly, and the PPP pathway was activated in the last month of cold stratification. During the process of natural stratification, GA and IAA contents increased gradually, ABA content decreased gradually, at first ZR contents was decreased, and then increased. The ratio of GA/ABA, IAA/ABA and ZR/ABA increased gradually.