Effects Of Combined Application Of Nitrogen,phosphorus And Potassium On The Growth And Main Active Component Of Tripterygium Wilfordii

The wild resources of Tripterygium wilfordii are decreasing rapidly with the discovery of its new medicinal values and the increasing market demand.However,the research on the cultivation technology of T.wilfordii is lagging behind,and the lack of supporting planting management technology has become a limiting factor in the cultivation of T.wilfordii.This experiment was conducted in Pingyuan Village,Baisha Town,Yangxin County,Huangshi City,Hubei Province.The 3414 complete fertilization scheme was used to explore the relationship between yield and quality with seasons or planting years under the fertilizer treatments by measuring the growth index（plant height,root fresh weight,etc.）,and physiological index（soluble sugar,total nitrogen,total phosphorus,total potassium content）,and active component content（such as triptolide and celastrol）and other index（alcohol extract,ash content,heavy metals）,in order to determine the suitable harvest season or growth years and the best fertilization scheme for the cultivation of T.Wilfordii,and provide the scientific support for the standardized cultivation of T.Wilfordii in Hubei Province.The main results are as follows:The plant height of T.wilfordii increased with the increase of growth years,but the growth rate gradually slowed down.The average drying rate of the fresh roots was 0.52.The growth rate of fresh root weight of T.wilfordii increased year by year with the increase of growth years after transplanting.When the roots were used as medicinal materials,the fresh roots of four-year-old could get higher yield.The fresh root weight of T.wilfordii experienced a rapid growth period from May to September in a year,and the accumulation of root dry matter increased significantly at the same time,and later followed a slow growth period which no obvious change of the root dry matter was observed from September to December.So that it can be harvested in September or December just based on the yield of roots.The content of triptolide in T.wilfordii roots increased firstly and then decreased among the different growth years.The roots harvested after four years’growth could obtain the higher output of yield and triptolide monomer content in the roots.The accumulation of triptolide in the roots in a year decreased slightly and then increased rapidly,and reached the maximum accumulation in December.Therefore,the highest triptolide output in roots harvested in December can be obtained.The most beneficial fertilization treatments for the accumulation of triptolide in the roots of T.wilfordii is that of N₂P₂K₂treatment.The celastrol content in the roots of T.wilfordii decreased firstly and then increased under different growth years,and more celastrol content in roots harvested after four years’growth can be also obtained.The content of celastrol reached the maximum accumulation in May in a year.No significant difference of total celastrol in roots per plant was found between May and December based on the fresh weight and dry ratio of roots,and the content of celastrol.So that the higher yield,and the output of triptolide and celastrol monomers in roots harvested in December can be simultaneously obtained on the basis of the fresh weight and triptolide content in different periods in a year.N₂P₂K₂was the most important treatment for celastrol accumulation in a year.The overall distribution of triptolide and celastrol in different organs was that:root>leaf>stem.The triptolide content of leaves in May was significantly lower than that in September,and the content of its celastrol was significantly higher than that in September.The content of triptolide and celastrol in the stem is extremely low in the different period.The contents of total nitrogen,total potassium and soluble sugar in the roots and leaves of T.wilfordii were generally higher than those in the stems during the different periods in a year.The content of alcohol extract in the roots of T.wilfordii under the different fertilization treatments in different years,ranged from 15.45%to 23.02%,with an overall average of 19.02%;the total ash content in the roots of T.wilfordii ranged from3.95%to 6.43%;the content of heavy metals（such as Cd,Cu,Pb）in the two-year-old roots of T.wilfordii is generally higher than that of the three-year-old ones.The results of this experiment mainly based on the yield and the contents of triptolide and celastrol in roots most commonly used as medicinal materials showed generally that the best scheme of combination fertilization of nitrogen,phosphorus and potassium for cultivation of T.wilfordii in Hubei is that N₂P₂K₂treatment,which the optimum application amount of nitrogen,phosphorus and potassium are 313.04kg N/hm²,104.94kg P₂O₅/hm²and 129.94kg K₂O/hm²,respectively,and the best harvest time is that in winter season growing for four years after transplanting the seedlings of T.wilfordii.In addition,that the leaves of T.wilfordii in our study were found to contain a higher content of triptolide or celastrol in September and in May,respectively,showed a good application and development value in future.