Insight Into The Mechanism Of Panax Notoginseng Under Continuous Monoculture And Evaluation Of Microbial Fertilizer Remediation

Panax notoginseng is a traditional Chinese medicinal plant that belongs to the family of Araliaceae Panax.However,continuous planting will cause a series of problems,for example,low yield,poor quality,plant diseases,insect pests rampant and so on.These have devastating effects on soil ecosystems and agricultural production,even affect the sustainable development of the P.notoginseng industry and the economic benefits of herbal medicine.therefore,it’s great the practical significance to explore mechanism of P.notoginseng under continuous monoculture and seek to mitigation measures of improving the obstacle.The study used The“Yunnan P.notoginseng”as the test material,conducted P.notoginseng under continuous monoculture was used two kinds of mixtures are made by self-made microbial fertilizer,EM and TRI,respectively.Six treatments soils included no-plant(CK),newly-plant(NP),newly and diseased plant(NP-DP),secondly-plant(SP),effective microorganism fertilizer(EM),Trichoderma fertilizer(TRI)were investigated.This study utilizated the basic principle and technology of modern molecular biology and ecological science to research and analysis the three major obstacle factors,so that insight into the mechanism of P.notoginseng under continuous monoculture.Different fertilizer treatments will be evaluated the remediation on continuous monoculture of P.notoginseng,in order to provide a theoretical basis and scientific way for Chinese continuous cropping obstacle.The main results and conclusions are listed as follows:(Ⅰ).About continuous cropping obstacle mechanism research results showed that continuous planting of P.notoginseng significantly reduced pH value,available main nutrients,available micronutrients and some enzyme activities on rhizosphere soil,while the total main-nutrients and micronutrients have a slight decline,even some elements were significantly enriched.Therefore,this study considered that soil acidification aggravated after continuous cropping,resulting in nutrient sequestration,combined with soil enzyme activity disorder,and plants could not absorb,resulting in continuous cropping obstacles of P.notoginseng.Secondly,allelopathic substances in P.notoginseng rhizosphere did not accumulate along with the increase of continuous cropping years,and did not reach the threshold of "self toxic effect".Therefore,it is excluded that the self toxic effect of allelochemicals in the rhizosphere secretions is the main reason that leading to P.notoginseng under successive cropping obstacles.Finally,on the results of microorganisms isolated and quantitative analysis,co-culture of microorganism and secretion.we founded that the content of pathogens increased while the content of probiotics decreased significantly in P.notoginseng rhizosphere soil,and most of root exudates selectively promote pathogen reproduction.Mainwhile,the root exudates can selectively promote the reproduction of pathogens and inhibite growth of probiotics.so that aggravate the imbalance of microbial proportion in P.notoginseng rhizosphere soil and the pathogens become advantage groups.A series reduction of continuous cropping appeared,such as the decline of resistance and the reduction of the output.Therefore,this study suggests that the imbalance of rhizosphere microbial community structure mediated by rhizosphere secretions is the cause of P.notoginseng under continuous monoculture.(Ⅱ).The continuous cropping obstacle of P.notoginseng is extremely prominent,plant are almost total destruction after 1 years.The use of microbial fertilizer EM and TRI increased the germination rate,seedling rate and yield significantly.These field growth are similar to the firstly planting,and the fertilizer alleviated the obstacles of P.notoginseng under continuous monoculture.But,TRI is better than EM fertilizer at the effect of increasing production.(Ⅲ).The application of EM and TRI fertilizer not only can improve soil pH value and soil fertility,but also adjust the microorganisms proportional imbalance of pathogenic and probiotic in rhizospher soil microenvironment.By DGGE and HTS analysis,it was found that there was a great difference in the community structure of fungi and bacteria between SP soil and NP soil,indicating that continuous cropping resulted in significant changes of microbial community structure.However,the bacteria community of NP soil and TRI soil are most similar,followed by EM soil.The fungi community of NP soil and EM soil are most similar,followed by TRI soil.This shows that soil microbial community structure and biodiversity were gradually repaired,because microbial fertilizer can regulate microbial community structure and functional diversity to evolution from secondly planting to firstly planting.(Ⅳ).This study isolated many microbial strains.Some antagonistic strains are selected to prevention pathogens and others are used for soil acidification and element sequestration,microorganism related to acidification and nutrition functional,for example.This study can reserve highly active microbial resources for further research that explore the restoration problem of fertilizer to P.notoginseng under cropping obstacles.This paper systematically summaries the causes of continuous cropping obstacle of P.notoginseng,and comprehensive evaluates the repaired effect of two kinds of microbial fertilizer.Meanwhile,This study used traditional pure culture and modernizational exempting culture methods to reveale comprehensively before and after continuous cropping fertilizer on microbial community structure in rhizosphere soil and composition variation.It not only screened a number of valuable resources to control soil borne diseases,but also provided effective ways and theoretical basis for solving the problem of continuous cropping obstacles.