Study On The Effect Of Bioenhanced Reduction Combined With Microbial Fungi On The Prevention And Control Of Continuous Cropping Obstacles In Celery

The large area of celery cultivation in China and the prevalence of continuous cropping have led to increasing problems of soil acidification,secondary salinization and soil-borne diseases.This thesis uses bioreduction methods to improve secondary salinity and kill pathogenic bacteria in the soil,while combining microbial agents to replenish the missing microorganisms in the soil ecological niche to effectively prevent and control celery crop disorders.The study was carried out on celery in a serious crop-blocking facility,using an amendment(lime nitrogen)and organic material(wheat bran)in combination with irrigation and high-temperature soil boring,and the disease-resistant microbial agent Bacillus cereus BZ6-1 to effectively prevent and control crop-blocking in the facility.The results of this study were as follows:1)Survey on the occurrence of continuous crop barriers in vegetable greenhouses in facilitiesA survey of the occurrence of continuous crop barriers in 12 vegetable greenhouses in Changzhou and Gaoyou found that the main diseases of vegetables were anthracnose and root rot,with disease incidence generally ranging from 10.0%to 25.0%.The pH of the soil in the greenhouses ranged from 5.64 to 8.27,with some vegetable greenhouses having a pH of 6.50 or less and a serious problem of soil acidification.Soil conductivity values ranged from 26 mS/m to 194 mS/m,with 91.7%of the vegetable sheds having secondary salinisation problems(>34 mS/m)and 8.3%of the sheds even having heavily salinised soils(>187 mS/m).There is a correlation between the incidence of soil-borne diseases in facility soils and soil acidification and secondary salinisation.2)Effect of bioaugmented reduction and lime nitrogen sterilization on the physicochemical properties and microbial community structure of inter-root soils of successive celery cropsThis experiment was designed with flooded high temperature smothering(CW),bioenhanced reduction(O1W;5000 kg/hm bran,O2W;10000 kg/hm bran,O3W;15000 kg/hm bran),lime nitrogen sterilization(S1W,S2W,S3W;300 kg/hm lime nitrogen,600 kg/hm lime nitrogen,900 kg/hm Lime N)and other amendments.After treatment with bioreduction and lime nitrogen sterilisation,the nitrate-nitrogen content of the soil was significantly reduced compared to CK while pH,organic matter,total nitrogen and fast-acting phosphorus were all significantly increased.The nitrate-nitrogen content of the S3 W treatment with lime nitrogen sterilisation had a minimum value of 49.0 mg/kg,40.7%lower than that of CK.The maximum pH value of the soil after the O3W treatment was 6.78,14.1%higher than that of CK.The maximum soil organic matter content in the O3W treatment was 34.4 g·kg-1,an increase of 43.9%compared to CK;the maximum soil effective phosphorus content in the O3 W treatment was 87.3 mg/kg,an increase of 20.2%compared to CK.Lime N treatment also increased the relative abundance of Firmicutes in the soil.The negative correlation between nitrate-nitrogen and Actinobacteriota,Firmicutes and Bacteroidetes by RSD analysis indicated that the lime nitrogen treatment reduced the nitratenitrogen content of the soil and improved the relative abundance of Actinobacteriota,Firmicutes and Bacteroidetes in the soil,The best results were obtained by lime-nitrogen treatment in reducing nitrate nitrogen and improving the growth environment of Actinobacteriota,Firmicutes and Bacteroidetes in the soil.3)Effect of bioaugmented reduction combined with microbial agents on soil chemical properties,microbial community structure and celery qualityIn order to fully exploit the effect of biofortified reduction combined with microbial bacterial agent to alleviate the continuous crop barrier,different trials were designed including:biofortified reduction(OW;wheat bran),lime nitrogen sterilization(SW;lime nitrogen),biofortified reduction(SOW;wheat bran,lime nitrogen),biofortified reduction combined with microbial bacterial agent(OJW;wheat bran,microbial bacterial agent BZ6-1),lime nitrogen sterilization combined with(SJW;lime nitrogen,microbial agent BZ6-1)and bioaugmented reduction combined with microbial agent(SOJW;wheat bran,lime nitrogen,microbial agent BZ6-1).The results showed that SOJW treatments were effective in improving soil chemistry and increasing yields.The SOJW treatment at celery harvest time had a pH of 7.17,conductivity value of 55 mS/m,nitrate-N of 76.8 mg/kg,organic matter of 25.8 g/kg,effective phosphorus of 72.7 mg/kg and fast-acting potassium of 208 mg/kg,which increased by 16.2%,-36.8%,-38.7%,11.7%,7.1%,156.8%,respectively,compared to CK,The maximum fresh and dry weight values of celery after SOJW treatment were 38.82 g and 5.78 g respectively;the soluble sugar content in celery reached 8.94 g/kg,an increase of 15.50%compared to CK;the nitrate content in celery was 987.6 mg/kg,a decrease of 19.3%compared to CK.During the celery harvest period,the pH value of SOJW treatment was 7.17,the conductivity value was 55 mS/m,the nitrate nitrogen was 76.8 mg/kg,the organic matter was 25.8 g/kg,the available phosphorus was 72.7 mg/kg,and the available potassium was 208 mg/kg.Compared with CK,the SOJW treatment increased by 16.2%,-36.8%,-38.7%,11.7%,7.1%,and 156.8%,respectively.The maximum fresh and dry weight values of celery after SOJW treatment were 38.82 g and 5.78 g,respectively;The soluble sugar content in celery reached 8.94 g/kg,which increased by 15.50%compared to CK;The nitrate content in celery is 987.6 mg/kg,which is 19.3%lower than CK.The effect of different treatments on soil microbial community structure showed that SOJW treatment reduced the relative abundance of Fusarium,which causes a variety of soilborne diseases,while the relative abundance of Pseudomonas,which suppresses pathogens and promotes plant growth,and Sphingobacterium,which controls root knot nematodes,increased.increased.The SOJW treatment was effective in suppressing the abundance of Fusarium in the soil by fluorescence quantification.In summary,the study of the response mechanisms of different treatments to succession barriers in celery facilities revealed that the SOJW treatment(wheat bran,lime nitrogen and microbial agent BZ6-1)in combination with biofortified reduction methods can effectively prevent and control succession barriers and maintain the ecological balance of vegetables in facilities.