Effects Of Exogenous Phosphorus On Seedling Growth And Soil Microecology Of Phellodendron Chinense Schneid

Phellodendron chinense Schneid is derived from the plants of genus Phellodendron of Rutaceae family.As a traditional Chinese medicinal material,Phellodendron chinense Schneid is widely planted in Hubei Province,Northwest of Hunan Province and East of Sichuan Province,etc.Bark is the main medicinal part,which mainly contains alkaloids,flavonoids and other compounds.Among these compounds,the berberine content in alkaloids is the highest,followed by phellodendrine.Berberine,which is widely used in clinical treatment and research,has anti-tumor,bacteriostatic and anti-inflammatory effects.Due to the increasing demand in market,the wild Phellodendron chinense Schneid resources has been cut down excessively,and has already been listed as a national second-class protected plant.Hunan province belongs to the red soil area where the available phosphorus is in shortage in the soil,and the shortage of available phosphorus has a negative effect on the growth and accumulation of medicinal ingredients of Phellodendron chinense Schneid.Therefore,the study on the effects of exogenous phosphorus on the growth,accumulation of medicinal ingredients and soil micro-ecology of Phellodendron chinense Schneid can provide a theoretical basis for the scientific cultivation of Phellodendron chinense Schneid.In this study,one-year-old Phellodendron chinense Schneid seedlings were used as experimental materials for the systematical study of effects of A(control),B(concentration 0.1%KH2PO4),C(concentration 0.3%KH2PO4)and D(concentration 0.6%KH2PO4)on its growth,medicinal ingredients content,soil physical and chemical properties,microbial community structure and diversity.This thesis aims to reveal the mechanism of growth response to exogenous phosphoru,and to provide a theoretical basis for the accurate cultivation of Phellodendron chinense Schneid.The main results are as follows:1.According to the results of the analysis on the growth state of Phellodendron chinense Schneid,after being treated with the concentrations of 0.1%,0.3%and 0.6%phosphate fertilizer,the growth rate of plant height of Phellodendron chinense Schneid seedlings from the experimental group increased by 0.97%,1.32%and 0.23%respectively than that of the control group.However,0.3%phosphate fertilizer significantly increased its fresh weight,which was 1.13 times than that of the control group,while 0.6%phosphate fertilizer decreased its fresh weight,which was 75%of the control group;Exogenous phosphate fertilizer could increase the content of chlorophyll a,improve the net photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpiration rate of Phellodendron chinense Schneid leaves.Meanwhile,the level of SOD activity was also promoted.Compared with the control group in the same period,after 30 days of exogenous phosphate fertilizer treatment,the contents of berberine and phellodendrine in stem bark and fibrous root of Phellodendron chinense seedlings were not significantly affected but decreased remarkably in the main root bark.After being treated with the concentrations 0.1%,0.3%and 0.6%phosphate fertilize,the contents of berberine were 66%,62%and 76%,respectively of that of the control group,and the content of phellodendrine were 70%,68%and 78%,respectively of that of the control group.2.According to the study on soil physical and chemical properties,the external application of phosphate fertilizer could effectively increase soil total phosphorus content and available phosphorus content,and the promoting effect was proportional to the concentration of phosphate fertilizer;The content of total nitrogen,nitrate nitrogen and ammonium nitrogen in soil were not significantly affected by exogenous phosphate fertilizer;The external application of phosphate fertilizer could effectively increase the contents of soil organic matter,total carbon and available potassium,meanwhile the promoting effect was proportional to the concentration of phosphate fertilizer.3.According to the high-throughput sequencing data,after 30 days of treatment with different concentrations of phosphate fertilizer,the dominant soil bacteria of the control group and the experimental group in the Phellodendron chinense seedlings were the same,and the relative abundance of more than 1%included Bacteroidetes,Firmicutes,Proteobacteria,Actinobacteria,Verrucomicrobia,Cyanobacteria,Patescibacteria,Acidobacteria,Tenericutes and Spirochaetes.Compared with the control group in the same period,the soil bacterial structure and diversity did not change significantly under 0.1%and 0.3%phosphate fertilizer treatment for 30 days,while the total amount of bacteria decreased under 0.6%phosphate fertilizer treatment,at the same time the relative abundance of Cyanobacteria and Patescibacteria in the dominant bacteria was significantly lower than that of the other three groups.Furthermore,RDA analysis found that the relative abundance of Cyanobacteria and Patescibacteria was negatively correlated with soil available phosphorus(AP)content and total phosphorus(TP)content,also positively correlated with pH value.It proved that the available phosphorus(AP)content and total phosphorus(TP)content were the main factors affecting the structure and abundance of soil bacterial community.To sum up,the appropriate concentration of exogenous phosphate fertilizer can promote the growth and development of Phellodendron chinense seedlings.Different phosphorus concentrations have different effects on the growth and development,the medicinal ingredients,and the soil micro-ecology of Phellodendron chinense seedlings.