| Soil salinization has become a worldwide ecological and environmental problem.The area of saline-alkali soil in China is as high as 34.6 million hectares,accounting for about 4.88%of the available land area in the country.Soil salinization leads to the decrease of soil fertility and affects the growth of plants in saline-alkali land,which seriously restricts the development of agriculture and animal husbandry.The biological improvement method has stable effect and strong persistence,and is increasingly applied to the improvement of saline-alkali soil.Planting halophytes and salt-resistant plants on saline-alkali soil can desalinate saline-alkali soil,while microorganisms can directly or indirectly promote the growth of plants on saline-alkali land.In this study,the typical saline-alkali area-the Yellow River Delta saline soil was used as the research object.The soil of different plant types in the Yellow River Delta was collected for the study of soil physical and chemical properties and microbial diversity.Isolation and cultivation of universal salt-tolerant rhizosphere bacteria Group,after inoculation with peat on different salinity and alkalinity gradient soil,through cotton growth and stress resistance physiological indicators such as germination rate,root length,plant height,chlorophyll,etc,research on microbial under salt stress on plant growth and the impact of art,parsing microbes and the interaction mechanism of salt-tolerant plant growth,to fully understand the optimization mechanism of root microenvironment.The main research results are as follows:1.The physical and chemical properties of different saline-alkali soil,different plant roots and non-root soil showed differences.The pH value of the rhizosphere and non-rhizosphere soils of Suaeda.salsa is significantly different(P<0.05).The root micro-environment of Suaeda.salsa can affect the soil pH to a certain extent,allowing plants to grow on saline-alkali soils;There was a significant difference in the salt content between the root system and the non-root soil,which was related to the salt tolerance mechanism of the plants.The contents of nitrogen and phosphorus in rhizosphere soil of corn,cotton,reed and salt-ground alkaloid rhizosphere were higher than that of non-rhizosphere soil.The plant rhizosphere soil has high nutrient elements content and low pH,which is more suitable for the survival and reproduction of microorganisms.2.In saline-alkali soils,the main bacterial phylums are Proteobacteria,Actinobacteria,Bacteroidetes,Chloroflexi,Acidobacteria,Firmicutes,Gemmatimonadetes,Verrucomicrobia,Cyanobacteria,and Patescibacteria.The bacterial community diversity and community richness in rhizosphere soil of the four plants were significantly higher than that in non-rhizosphere soil.There are more Proteobacteria and Firmicutes in the rhizosphere environment of moderately salt-tolerant plants,and more Acidobacteria and Gemmatimonadetes in the rhizosphere environment of mildly salt-tolerant plants,which is related to the salt tolerance of bacteria.3.Under the stress of salt and pH,the germination and seedling growth of cotton crops were obviously inhibited.This inhibition can be effectively improved by adding salt-tolerant dominant mixed flora.In the soil with aseptic group addition,the salinity tolerance of cotton seeds can only reach 1.0 g/L,while in the soil with bacterial group addition,cotton seeds can germinate in the environment with salinity of 2 g/L and seedlings can grow.Secondly,the salt-tolerant mixed bacteria can significantly improve various physiological indicators of cotton crop growth,including germination rate,germination potential,germination index,plant height,root length,plant dry weight,chlorophyll,Pro,MDA,SOD,POD,and CAT,compared to the cotton index added to the aseptic group,the average effect can be increased by about 2.3%.Therefore,the growth of crops can be promoted by adding a salt-tolerant mixed bacterial group to the saline soil. |
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