Studies On Physiological Mechanisms Of Seed Abortion In Ceratoides Arborescens

The thesis studied on the physiological characteristics of seed abortion in Ceratoides arborescens. The contents were composed of the seed setting rate, the enzyme activity, the endogenous hormones contents, the nutrient contents and the abortive mechanism of seed.The seed setting rates were different in different pollination modes and different types of Ceratoides arborescens. Geitonogamous seed setting rate (81.5%) was significant lower than xenogamous (93.7%), and the normal seed setting rate (93.2%) was significant higher than the light aborted seed setting rate (82.6%) and the high aborted seed setting rate (65.4%).The peroxidase and acpase activity in Ceratoides arborescens had a tendency of ascent with the seed development. The nitrate reductase activity during early period of seed development increased significantly and then decreased, and that in normal seeds was lower significantly than two types of aborted seeds. It was showed that the nitrate reductase activity partly affected the seed setting rate of Ceratoides arborescens.The contents of IAA,GA3 and ZR in normal Ceratoides arborescens seeds were higher than two types of aborted seeds, and that in xenogamous seeds were higher than geitonogamous seeds. The ratio of (IAA+GA3+ZR)/ABA in three types of Ceratoides arborescens seeds was high during the early period of seed development, and then had a tendency of descent with the development of seeds, and the ratio in normal seeds was higher significantly than two types of aborted seeds. It was suggested that the changes and the balance of endogenous hormones were closely related to the embryo abortion of Ceratoides arborescens.The nutrient contents were different between three types of Ceratoides arborescens, the contents of nitrogen,phosphorus and soluble sugar in normal seeds were higher than two types of aborted seeds, and the difference was significant during the most stage of seed development, in addition the content of nitrogen was positively correlated to the seed setting rate in the middle-Stage of seed development. It was suggested that nutrient content, especially nitrogen content, was one of the most important factor to affect the seed setting rate of Ceratoides arborescens.Analysis on the reasons of seed abortion showed that the seed abortion in Ceratoides arborescens was because of internal physiology factors, external environment factors and other synthesis factors. Lower activity of nitrate reductase, deficiency of nutrient content, especially nitrogen disturbance, deficiency of positive hormones and imbalance of hormones, to a certain extent, were the inducting factors for the seed abortion of Ceratoides arborescens.