Isolation Of Phosphate-Solubilizing Rhizobacteria In High-Salt Environment And Study On The Function Of Promoting Growth Of Maize

With the problem of soil salinity becoming more and more serious,the range of soil salinization in farmland in China is gradually increasing,so the growth of crops is threatened.Rhizosphere is the most direct area where plants interact in high salt environment.Microorganisms around rhizosphere can alleviate salt stress and promote growth.Rhizosphere microorganisms play an important role in plant growth,which can improve the resistance of plants and enhance the tolerance of plants to harsh environments.In this study,a salt-tolerant and growth-promoting rhizobacteria was isolated from maize roots by using 10% salt concentration LB medium as isolation and screening medium.Its molecular biological identification and growth-promoting test were carried out,and the effect of the salt-tolerant and growth-promoting rhizobacteria on maize growth was explored.According to physiological and biochemical experiments and molecular biology identification,this salt-tolerant rhizobacterium is Kocuria rhizophila.Experiments on the growth conditions showed that the bacteria could tolerate a wide range of temperature and pH,which indicated that the bacteria could adapt well to the changes of the environment.The optimum growth temperature and pH value of the strain were 34 ℃ and 7.The results of growth-promoting test showed that it had the functions of dissolving phosphorus,hydrolyzing protein and inhibiting pathogenic bacteria.The results of experiments on promoting effect of maize showed that the inoculation of Kocuria rhizophila had no significant effect on the germination rate of maize seeds in the absence of salt;under salt stress,the germination rate of maize seeds inoculated with Kocuria rhizophila increased by 20%;compared with the control,the inoculation of Kocuria rhizophila promoted the plant height and roots of maize plants.The changes of length were significantly increased;inoculation of Kocuria rhizophila could increase chlorophyll content of maize leaves,which enhancing photosynthesis of maize leaves;under salt stress,Kocuria rhizophila could increase Catalase activity of maize leaves to remove oxides,while reducing malondialdehyde of maize leaves.Content can slow down the damage of membrane system of maize leaves caused by salt stress,and then promote the growth of maize plants.Under salt stress,Kocuria rhizophila can increase the content of soluble sugar and soluble protein in maize leaves,maintain the balance of osmotic pressure of maize leaves,enhance the stress resistance of maize plants,and thus slow down the effects of salt stress on growth of maize plants.Therefore,Kocuria rhizophila can promote the growth of maize and alleviate the effects of salt stress on maize leaves.