Study On The Biological Mechanism Of Continuous Cropping Obstacles In Rehmannia Glutinosa And Its Reduction Measures

Rehmannia glutinosa Libosc.is a perennial herb of the Scrophulariaceae,and its roots are used in medicine,the clinical effect is accurate.As one of the “Four major Huaiqing medicines”,Rehmannia glutinosa Libosch.is an important Chinese medicinal herb.Continuous cropping obstacles are frequently encountered by Chinese medicinal herbs of roots and tubers,especially by Rehmannia glutinosa,whose obstacles lie in the hindered expansion of roots,more fibrous roots,poor yields and low commodity value.It takes 8-10 years to replant Rehmannia glutinosa after the first cultivation.With the recent increase in the demand,the contradiction between supply and demand has become increasingly serious,which has a huge impact on ensuring the safe use of Rehmannia glutinosa and the healthy development of related industries.Therefore,research on the causes and reduction techniques of rehmannia glutinosa crops has become a problem and a hot spot in the field of traditional Chinese medicine resources.Based on the "Recruitment of harmful microorganisms by Rehmannia glutinosa,which leads to the deterioration of the rhizosphere micro-ecological environment,resulting in continuous cropping obstacles,and the plant cannot grow normally and die" is an important mechanism for the occurrence of continuous cropping obstacles in Rehmannia glutinosa,this study focuses on the interaction between pathogens and antagonistic bacteria in its continuous cropping obstacles,revealing the occurrence and mitigation mechanisms of continuous cropping obstacles,by inhibiting the occurrence and proliferation of pathogenic microorganisms in the rhizosphere,innovating ideas and methods to alleviate continuous cropping obstacles in Rehmannia glutinosa.In this way,it provides the theoretical and technical support for the development of mitigation technology strategies and products to alleviate the obstacles continuous cropping in Rehmannia glutinosa.Studies on the pathogenic bacteria and antagonistic bacteria causing Rehmannia glutinosa continuous cropping obstacles have been conducted in Zhengzhou,Jiaozuo and other places in Henan Province in 2016-2019,which serve as a basis for further research of the mechanism and effect of the technological application of adding exogenous antagonistic bacteria and reductive soil disinfestation to reduce the continuous cropping obstacles in Rehmannia glutinosa.Conclusions are as follows:1.Fusarium oxysporum is an important pathogen causing continuous cropping obstacles in Rehmannia glutinosaThe pathogenic bacteria were isolated from the Rehmannia glutinosa plants,and the CTAB method was used to extract the DNA of the pathogenic bacteria.The ITS region and the elongation factor 1-alpha(EF-1 alpha)gene sequence were amplified and sequenced,and compared in the NCBI database.A phylogenetic tree was constructed from the sequence of the ITS region,and the species of the pathogen was Fusarium oxysporum.Through pathogen reattachment experiment,it was identified as an important pathogen causing continuous cropping obstacles in Rehmannia glutinosa.2.Bacillus tequilensis antagonizes the growth of Fusarium oxysporumBased on the previous research by the research group,it was found that the soil without planting Rehmannia glutinosa has the effect of reducing the barrier effect of Rehmannia glutinosa continuous cropping.Bacteria were screened and isolated from rhizospheric soil of the rotational crop of Rehmannia glutinosa,and through the antagonistic experiment,one of the strains(code: DU-1)was found to effectively inhibit the growth of Fusarium oxysporum,with the inhibition rate of 8.23%.By 16 S r DNA sequencing,the bacterium belongs to the genus Bacillus(Bacillus tequilensis),and the author named it Bacillus tequilensis DU-1.3.Bacteria mainly based on Bacillus tequilensis can effectively alleviate obstacles to continuous cropping of Rehmannia glutinosaBased on Bacillus tequilensis(DU-1),two kinds of bacteria preparations(codes T1 and T2)were applied to monocropping Rehmannia glutinosa.There was a significant yield increase.The yield of Rehmannia glutinosa with T1 increased by 407.1%,and the yield of Rehmannia glutinosa with T2 increased by362.1%.It can effectively improve the quality of Rehmannia glutinosa,the content of catalpol with T1 increased by 646.2%,and the content of polysaccharide increased by840.0%.The content of catalpol with T2 increased by 600.0%,and the content of polysaccharides increased by 540.0%.It could effectively improve the content of organic matter and nitrogen in the monocropping rehmannia field,and effectively improve the biological properties of the soil.The activities of acid phosphatase,urease and invertase were higher than those of the unstubbed monocropping field;the soil microbial community was improved to a certain extent,similar to that of the rotational cropping fields.The abundance of Bacillus was significantly increased,with 0.12% for T1 and 0.27% for T2.4.Reductive soil disinfestation can significantly improve the growth and quality of Rehmannia glutinosaRehmannia glutinosatation and waterlogging were carried out on the continuous cropping field of Rehmannia glutinosa,with no treatment as the CK.The results showed that: the survival rate of Rehmannia glutinosa,65.4% of reductive soil disinfestation,43.8% of waterlogging,23.2% of CK;yield,1626.1 kg/mu of reductive soil disinfestation,636.0 kg/mu of waterlogging,466.5 kg/mu of CK;catalpol content,reductive soil disinfestation of soil was 3.84 times that of waterlogging,and 4.45 times that of CK;Rehmannia glutinosa polysaccharide content,reductive soil disinfestation was 3.00 times that of waterlogging,and 4.74 times that of CK.