Under Low-phosphorus Stress Response Mechanism Of Tripterygium Wilfordii

Phosphorus is a key element for plant growth, it plays an irreplaceable role on the ecosystem that human survives in. However, the problem of insufficient phosphorus has become the main factor that influences the production of agricultural and forestry. The research of low-phosphorus stress adaptation Tripterygium wilfordii physiological and biochemical mechanism is of great practical significance.Up to date, the research of Tripterygium wilfordii is mostly on the structure of its constituents, Pharmacological effects, such as medicine, while the report about its artificial cultivation technology, physiological and ecological mechanism, and the factors that effect the growth of Tripterygium wilfordii is relative few. By the soil culture, the design of low- phosphorus stress test, the morphological and physiological response of Tripterygium wilfordii to different levels of low-phosphorus stress, this paper revealed the mechanism of its regulation to the absorption of phosphorus through the morphological and physiological changes, as well as the changes of concentration of Tripterygium wilfordii wilfordii Hook.F. in different parts of triptolide, providing the basis for its rational management.1) Low-phosphorus stress significantly affected the growth of triptreygium with different ages, and the response of Tripterygium wilfordii with different ages to low-phosphorus stress was different. One-year Tripterygium wilfordii was very sensitive to low-Phosphorus stress, as the degree of stress increased, the parameters declined rapidly, and it was not suitable for it to grow in low phosphorus soil. To some extent, three-years Tripterygium wilfordii can adjust itself to adapt to low phosphorus environment.2) Tripterygium wilfordii has a strong ability to adapt the environment with insufficient phosphorus, it can maintain a certain content of chlorophyll in the forest with low phosphorus, this can ensure the photosynthesis of plant and the formation of organic substance. Under the conditions of low-phosphorus stress, the photosynthesis of Tripterygium wilfordii was blocked, it can be showed as: the transpiration rate was reduced, the content of chlorophyll was down and the rate of phosphorus was declined. The degree of photosynthetic reflected the nutritional status of the plant, thus it can be used as a physiological indicator of phosphorus.3) Phosphorus stress seriously affected the morphological index of Tripterygium wilfordii with different ages: In order to grow better under the conditions of low-Phosphorus stress, the growth of Tripterygium wilfordii's diameter, the longest branches, and height was hindered. As the severity of phosphorus was increased, the content of dry matter of Tripterygium wilfordii with different ages was reduced and the root-shoot ratio was increased. The patterns indicators are the important judge for the nutritional status of plant.4) Under the low-Phosphorus stress, the activities of protective enzyme like SOD, CAI and POD, the content of MAD of proline in the plant would change correspondingly: both of the activity of SOD and the content of MDA increased apparently, and the activity of CAT ANT and POD decreased. The changes of the content of proline were different in the Tripterygium wilfordii with different ages: while the content of proline in the leave of one-year Tripterygium wilfordii was increased, the content of proline in the leave of three-years Tripterygium wilfordii was decreased. Under the same processing condition, compared to July , the content of proline and MDA , the activity of SOD and POD were increased , and the activity of CAT was decreased in October. This can reflect the physiological changes of plant in the adverse condition, and is significant to research of plant's stress injury and the resistance mechanism.5) The activity of soli enzyme may reflect the general level of soil fertility, usually the high activity of soli enzyme shows the high nutrient of soli.Under low-Phosphorus stress, the activity of catalase, sucrose and urease in the athe of Tripterygium wilfordii with different ages were decreased. Compared to July, the activity of catalase, sucrose and urease were decreased in October.6) Under the low-Phosphorus stress, the content of triptolide in the root and branches of Tripterygium wilfordii with different ages was decreased, and it would be decreased more apparently as the degree of the low-Phosphorus stress was streng then. As the growth of Tripterygium wilfordii, the content of triptolide in branches and roots were both increased, but the low-Phosphorus stress affected the accumulation of triptolide.7) The seasonal changes of physiological indicators in Tripterygium wilfordii also appeared in the adaptation to the high temperature and high light intensity. For instance, as the stomata closed,the transpiration would be decreased, and the content of chlorophyll would be reduced.