| Barrier soils are mainly formed by the deterioration of the soil’s own ecological environment due to excessive inputs of chemical fertilizers and pesticides,etc.,during modern agricultural production.The typical barrier soil type mainly has soil acidification,soil saline alkalinization as well as ecological barriers,and the specific forms of barriers are soil pinning,acidification,and salinization,in which the abundance of the soil microbial community and the activities of multiple related enzymes in the soil are severely decreased,thus resulting in the restriction of the biochemical transformation ability of soil nutrients,which seriously disrupts the soil microbial community structure and diversity and greatly negatively affects normal agricultural production.This study alleviates the occurrence of barrier soils by applying nitrogen-fixing and phosphate-solubilizing microbial fungicides in barrier soils,decreasing the use of agrochemicals,while improving the yield and quality of crops in barrier soils.Through the development of agromicrobial products,a series of social difficulties such as environmental facial source pollution and agricultural product safety caused by the over application of agrochemical products are circumvented,at the same time,through the flora research of ecological barriers,the potential biocontrol strains are analyzed,and new ideas are provided for the mining of beneficial microbial resources.The main results of this study are as follows:1、In this study,we investigated the effects of phosphate-solubilizing Aspergillus niger MJ1 individually and in combination with Pseudomonas stutzeri DSM4166,a wild-type nitrogen-fixing,and Pseudomonas fluorescens CHAO-nif engineered nitrogen-fixing on yield,quality,soil physicochemical properties,biomass carbon and phosphorus,and rhizosphere microbial community during Cucumber growth in saline-sodic soils.MJ1+DSM4166 and MJ1+CHAO-nif all increased the contents of alkaline hydrolysis N,total N,available P and available K in both surface 0-20 cm and deep 20-40 cm soils when compared to conventional fertilization.The MJ1+CHA0-nif treatment produced a significant 55.86%increase in yield over conventional fertilization-Significant differences were observed in Cucumber yield,protein and vitamin C contents among plants inoculated with nitrogen-fixing and phosphate-solubilizing after 30%conventional fertilization.MJ1+DSM4166 and MJ1+CHAO-nif did not significantly affect the microbial community in saline-sodic soils grown in Cucumber.The MJ1+DSM4166 and MJ1+CHA0-nif combinations can meet Cucumber growth requirements in saline-sodic soils at 30%fertilizer application rate reduction,thus providing new alternative techniques for achieving "Decreasing fertiliz,Increase production,and Increase efficiency" sustainable development and food safety in saline-sodic soils.2、The production yield,quality,soil physicochemical properties,biomass carbon and phosphorus and rhizosphere microbial communities during Lettuce growth in acidic soils were determined using the combinations of the phospholytic bacterium Aspergillus niger MJ1 with the wild type nitrogen-fixing Pseudomonas stutzeri DSM4166 and Pseudomonas fluorescens CHAO-nif engineered nitrogen-fixing,respectively.Data from this study showed that during growth of Lettuce in acidic soils,the contents of vitamin C,nitrate,soluble protein and crude fibre as well as soil physicochemical indicators organic matter,alkaline hydrolyzed N,total N,available P,available K and water-soluble salt showed significant responses to inoculating with the exogenous strains.The MJ1+CHA0-nif treatment resulted in a significant increase of 33.46%over conventional fertilization.MJ1+DSM4166 and MJ1+CHA0-nif affected the diversity and richness of the bacterial community in the rhizosphere but not the fungal community during Lettuce growth in acidic soils.Microbial systems,cellular processes,and metabolism related bacteria and saprophytic fungi were enriched and presumed to mediate the response to the exogenous strains MJ1+DSM4166 and MJ1+CHAO-nif.The MJ1+DSM4166 and MJ1+CHA0-nif combinations can meet the growth requirements of Lettuce grown in acidic soils at 30%reduced fertilizer applications and provide new alternative techniques for achieving "Decreasing fertiliz,Increase production,and Increase efficiency" sustainable development and food safety in acidic soils.3、To further explore the convenience of the extension application of nitrogen fixation and phosphorus hydrolysis complex microbial manure particles in different soil types and for the decreasing fertiliz and increase efficiency of field crops,this study conducted a high-density fermentation as well as exploration of the technological process of microbial manure granulation.In order to be suitable for mechanical seeding as well as blending with composite manure,microbial manure pellets hardness up to 19 N and water content as low as 10%while preparing granules with different functions of fungicide,antiphosphobacteria prepared as granules of organic matter+trace elements in the grain product,nitrogen fixing bacteria prepared as products of organic matter+fungicide by the way of strain characteristics adsorption of organic matter by fermentation broth,so that the final concentration of functional strain indicators of the products reached:final concentration of antiphosphobacteria 5 × 106 cfu/g,and the final concentration of diazotrophs was 2 × 108 cfu/g.Through the application and promotion of functional microbial manure in agricultural production processes,it can be expected to reduce 20-30%of the total fertilizer input,improve the yield and quality of crops,and alleviate the barrier soil effects,thus truly realizing the ability to insert the wings of science and technology for the modernization of agriculture.4、In this study,the bacterial communities of rhizosphere soils and roots with different degrees of rhizomegaly occurrence in Chinese cabbage,which represents one of ecological barriers,were targeted to reveal the composition and structure of rhizosphere soil and root bacteria in different treatment groups,and to identify potential biomarkers of rhizomegaly bacteria.The bacterial richness,evenness and coverage are poor in rhizosphere soils and roots that are heavily colonized with rhizobial diseases.There were significant differences in bacterial community structure between the high disease incidence(HR)and healthy(LR)rhizosphere soils and roots.The differential bacteria identi field between LR and HR rhizosphere soils and root systems were Bacillus asahii and Noccaea caerulescens,respectively,which are resistant to the occurrence of relatively severe rhizomegaly and can act as a biocontrol strain.For Chinese cabbage,pH was found to be an important factor and significantly correlated with the abundance of Bacillus asahii and Noccaea caerulescens.In addition,the difference in abundance of Bacillus asahii and Noccaea caerulescens in HR soil and root systems also suggests their potential as bioindicators for developing severe rhizomegaly.This study provides new insights into the relationship between soil and root bacterial communities and the etiology of root swelling disease in Chinese cabbage,and the identification of resistant strains provides candidate species for monitoring and biocontrol of root swelling disease. |
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