The Screening And Identification Of Effective Salt-tolerant And Growth-promoting Bacteria Strains Of Cucumber And The Preparation Of The Bacterial Compound

Soil salinization seriously affects agricultural production and ecological environment,which will cause plant physiological drought and imbalance of absorption of nutrient elements,and seriously affect plant growth.In order to realize the sustainable development of agriculture and rational utilization of land resources in China,it is of practical significance to carry out comprehensive management and scientific overall management of salinized soil.In this experiment,62 salt-tolerant strains stored in the laboratory were isolated and screened to identify the characteristics of routine strains in the laboratory,and combined with the 8 strains purchased from the center of bacteria,a petri dish test was carried out to explore the effect of promoting growth of the plants.After biological identification,a petri dish test was carried out to further explore the plant growth-promoting effect.After preliminary screening of salt-tolerant growth-promoting bacteria,pot culture experiment of mixed irrigation with bacterial liquid was carried out.To select the strains which can promote plant growth and soil activation,and explore the research development of salinized soil bio-conditioning agents with high efficiency.It provides a theoretical basis for the exploitation and utilization of microbial resources in Ningxia and provides a basis for the research and development of more mature fungicides,so as to restore the sustainable and efficient production of agriculture in saline-alkaline areas of Ningxia.In this experiment,two high-efficient salt-tolerant strains,NX-3 and NX-4,were screened out by NA plate screen and growth curve,and the salinity tolerance of two strains was 14%,respectively.At the same time,the experiment of promoting the growth of cucumber seeds in a petri dish in the laboratory was carried out.The dominant growth promoting bacteria,NX-48,NX-59 and NX-48,which could promote the growth of cucumber seedlings under different salt concentration gradient,were screened out.The seed vigor index of NX-59 and NX-62 treatments were 30%,4.5%and 1.97 higher than that of CK,respectively.The lateral root length of cucumber seedlings treated with strain NX-48 increased by 27.75%.At the concentration of 100mmolNaCl,the seed vigor index was significantly increased by 20%,1.97%and 57.20%,respectively,with the addition of strain NX-48,NX-59 and NX-62 compared with that of CK.Strains NX-3 and NX-4 have the ability to fix nitrogen and NX-62 has the activity of ACC deaminase,which makes the strain have the ability to promot growth,which is of great significance for the further research and development of compound fungicides.The combination of the modified salinized soil and the growth-promoting strain of the cucumber seedling shows that after the compound strain is added,the plant stem,the content of the chlorophyll and the fresh weight of the plant are all significantly greater than that of the CK and the addition of the salt solution,and the application of the compound microbial agent increases the adaptability of the plant to the environment,the salt tolerance of the cucumber seedlings can be effectively improved,and the growth and development of the cucumber seedlings can be promoted After application of the compound bacterial liquid under the salt stress environment,the pH value of the soil is obviously increased,the EC value is obviously reduced,the EC value of the soil under the salt treatment is 0.93 mS/cm,and belongs to the salinized soil,and the NX3-48 treatment group of the bacterial liquid is added to obviously lower the EC value of the soil,and finally the salinized soil The soil EC value was 0.75 mS/cm,the content of soil organic matter was decreased by adding bacterial solution NX4-48 and NX4-56,the content of soil available phosphorus was significantly higher than that of only adding salt solution under each treatment,the content of total nitrogen and available potassium was not significantly different from that of the treatment of adding only salt solution.The activities of catalase,sucrose,and phosphatase in soil maintained high level after adding mixed bacteria solution.In conclusion,we can see that the application of mixed bacterial solution can effectively promote cucumber growth and improve the salinized soil environment.The comprehensive evaluation showed that the treatment effect of NX4-62 was the best.Through morphological,physiological and biochemical characteristics and molecular identification,Strains NX-3 and NX-59 were Bacillus licheniformis,NX-4 was Bacillus.sp,NX-48 and NX-62 were Bacillus subtilis.In order to explore the optimal fermentation conditions of the mixed bacteria solution,the effects of different carbon sources,nitrogen sources,temperature,initial pH value and the amount of the liquid on the fermentation effect of the mixed bacteria solution were investigated in this experiment.The results showed that the optimum growth conditions were as follows:glucose as the best carbon source,yeast extract powder as the best carbon source,the optimal culture temperature of 30?,and the optimal aeration of pH 7.0?7.5,as the loading volume of 30 mL/500mL.