Analysis The Pathogen Causing By Root Rot And Rust Rot In Ginseng And Screening Of Antagonistic Bacteria

As a perennial herb of the genus Araliaceae,Ginseng is of great medicinal value.Since ginseng is susceptible to infection by pathogenic bacteria during the planting process,the isolation and identification of pathogenic bacteria in the rhizosphere soil of ginseng and the screening of resistant bacteria are very important.Fusarium solani and ginseng rust rot were isolated and screened from the pathogenic ginseng plants.The possible factors causing ginseng diseases were analyzed by analyzing the bacteria,fungal community structure and diversity index and soil physical and chemical tests on the rhizosphere soil and healthy ginseng rhizosphere soil of patients.The biocontrol strains with stable antagonism against ginseng root rot and ginseng rust were isolated from the rhizosphere soil of ginseng and wild rice rhizosphere soil,and then identified.The biocontrol strains were transferred back to ginseng stem for reconnection verification,and the main findings are as follows:The pathogens were screened from the affected patients and identified as Fusarium solani and ginseng rust by ITS sequence analysis.Through soil physical and chemical tests on the rhizosphere soil and healthy ginseng rhizosphere soil of the patients,it is speculated that the effective potassium content and pH value of ginseng rhizosphere soil have significant effects on the growth of ginseng;effective phosphorus content,organic matter content,total phosphorus content,total nitrogen content,available nitrogen,and conductivity values may affect ginseng growth.Based on the analysis of community structure and diversity index of rhizosphere soil and healthy ginseng rhizosphere soil,the results showed that the richness and Shannon diversity index of bacteria and fungi in the rhizosphere soil of diseased ginseng were significantly different from that of healthy ginseng.A biocontrol strain C10 with antagonistic effect on ginseng root rot was screened from the rhizosphere soil of ginseng,and the inhibition rate was 83.95%.It was identified as Bacillus amyloliquefaciens by 16 S rDNA sequence analysis.Two strains of biocontrol strains G6 and A2 which had antagonistic effects on ginseng rust rot were isolated from the rhizosphere soil of wild rice,and the antibacterial effect of A2 was 81.54%.By 16 S rDNA sequence analysis,G6 was identified as Streptomyces,A2 as Streptomyces.In the validation test of bacteria inoculation back to ginseng stems,antagonistic bacteria A2 and G6 showed no obvious damage to ginseng stem along with decay alleviation of ginseng stem to a certain extent,no obvious destruction obseved on ginseng stem,but antagonist C10 could inhibited the growth of root rot fungi and slowed down the decay of ginseng stem to a certain extent.The results showed that the antagonistic bacteria A2,G6 and C10 had certain biocontrol effects.