Study On Effect Of Continuous Cropping Obstruction Of Fritillaria Taipaiensis P.Y.Li And Its Meitigation Measures

Objective:The relationship between the rhizosphere soil bacterial and fungi community structure,Variation of soil factors and bulb quality of Fritillaria taipaiensis with different growth years was studied,and the the reasons for continuous cropping obstacles of Fritillaria taibaiensis were analyzed.In addition,through the combination of room temperature potted inoculation test and indoor analysis,microbial fertilizer was used to improve the quality of Fritillaria taipaiensis and further explore the mitigation measures for continuous cropping.Methods:High-throughput sequencing technique was used to determine the 16 S r DNA sequence of bacterium and ITS sequence of fungus in different growth years,and to analyze the composition,abundance,distribution,alpha diversity index of species,beta diversity and microbial communities diversity among different sample groups.Combined with the variation of soil factors under continuous cropping conditions,found the relationship between soil microorganism,soil fertility and quality of Fritillaria taibaiensis.The 3 and 4 year old of Fritillaria taipaiensis were used as research materials to observe the effects of microbial fertilizer on the infection rate and intensity of root mycorrhizal fungi,the physiological and biochemical indexes of plant,the number of microorganisms in rhizosphere soil,the activity of soil enzymes and the quality of medicines in sterilized soil..Results:(1)With the increase of growth years,the relative abundance of Lactobacillus,Gemmatimonas,Bryobacter and Bacteroides in rhizosphere soil of Fritillaria taibaiensis decreased gradually,while the relative abundance of Methylotenera,Pseudomonas and Sphingobium increased.(2)With the increase of growth years,the relative abundance of Pseudogymnoascus in rhizosphere soil of Fritillaria taibaiensis decreased gradually,while the relative abundance of pathogenic fungi including Fusarium,Gibberella,Volutella,Colletotrichum and Peziza increased.(3)With the increase of growth years,the content of available N,available P and organic matter in rhizosphere soil of Fritillaria taibaiensis decreased,the activity of protease in rhizosphere soil increased,the activity of urease,acid phosphatase and alkaline phosphatase decreased,catalase and sucrase activity decreased firstand then increased;the peimisine and total nucleosides content decreased first and then increased,and the total alkaloids content decreased.(4)With the increase of growth years,the content of available Fe,available Mn,available Zn and available Cu in rhizosphere soil of Fritillaria taibaiensis decreased,the content of available Mg and available B in rhizosphere soil increased,the content of available Ca decreased first and then increased.(5)The results showed that The 3 and 4 year old of Fritillaria taipaiensis P.Y.Li built good symbiotic relationship with exogenous rhizosphere soil beneficial microorganisms.Compared with CK group,the chlorophyll and carotenoid content in leaf of 3 years Fritillaria taipaiensis P.Y.Li were increased by seeding microbial fertilizer.The activities of three protective enzymes(CAT,SOD and POD)in leaves were all significantly increased;the content of soluble protein and sugar was also increased.However the content of malondialdehyde(MDA).The application of microbial fertilizer increased the number of culturable bacteria,fungi,actinomycetes,and the activities of soil rhizosphere enzymes(protease,urease,acid phosphatase,neutral phosphatase,alkaline phosphatase,catalase and sucrase)were significantly increased.It has obvious promoting effect on alkaloids and nucleosides in bulbs of Fritillaria taibaiensis.The application of microbial fertilizer reduced the number of fungi and catalase activity in rhizosphere soil of 4 years Fritillaria taibaiensis,and the other changes were the same as those of 3 years.Conclusions:Long-term continuous cropping will lead to accumulation of pathogenic bacteria in rhizosphere soil of Fritillaria taibaiensis,decrease of beneficial bacteria and soil fertility,which was not conducive to the growth and development of Fritillaria taibaiensis.The inoculation of beneficial microorganisms in exogenous rhizosphere soil improved the structure of microbial community in rhizosphere soil,increased soil fertility,promoted the growth of Fritillaria taibaiensis after continuous cropping,and effectively increased the accumulation of alkaloids in bulbs,which was conducive to the the quality and high yield of Fritillaria taipaiensis P.Y.Li.The results will provide references for promoting continuous cropping obstacles of Fritillaria taibaiensis.