Isolation Of Saline-alkaline Tolerant PGPR Of Desert Plant And Their Effect Of Growth Promotion And Mechanism On Three Plants Under Salt Stress

Soil-salinity limited plant production,is one of the most serious soil environment problem.Plant growth-promoting rhizobacteria(PGPR)can promote the growth of plants under salinity stress;application of PGPR is one of the most promising biological measures to improve saline-alkali land.Desert lacking of rain and the soil salt-alkali being very high often,is possible the rich resource of salt-tolerant PGPR strains.This study was based on spred and streak plating technique,separated and purified salt-tolerant of PGPR of Inner Mongolia desert plant rhizosphere soil,on Ashby medium,phytate-phosphorus medium and inorganic-phosphorus medium,the bacteria of nitrogen-fixation,phytate-phosphorus-solubilizing and inorganic-phosphorus-solubilizing were screened preliminarily;Based on 16S rRNA gene sequences,strains were preliminary classified;then analyzed their abilities for nitrogen-fixation,phytate-phosphorus-solubilizing,inorganic-phosphorus-solubilizing,siderophore-producing,1-aminocyclopropane-1-carboxylate(ACC)-producing and indole acetic acid(IAA)-producing,and combining the wheat emergence test rapid screened for strong features strain as inoculum of microbial fertilizer(according to strain number and number of strains respectively representated a single strain and compound strains granular fertilizer.NK and CK respectively on empty carrier particles and blank control of no particles of bacterial manure or empty carrier).Research of the growth-promoting effect and mechanism of PGPR on wheat,oats and canopy under salt stress were conducted.The main results and conclusioins are as follows:1.PGPR groups composition:strains of 203 were screened.mainly divided into 40 genera,wtih the dominant genera(>5%)Enterobacter(19.21%).Bacillus(12.8%),Scopulibacillus(11.82%),Arthrobacter(9.35%)and Pseudomonas(7.88%).Among them,46 of PGPR strains habituated traits of nitrogen-fixation,phytate-phosphorus-solubilizing,inorganic-phosphorus-solubilizing,siderophore-producing,ACC-deaminase-producing,IAA-producing and salt-tolerant,dominated with the genus Enterohacler,the traits most remarkable composed 18 strains of PGPR(C18),also dominated with Enterobacter.2.Effect of compsite PGPR on potted wheat under salt stress:compsite strains(the above strongest features 18 strains of PGPR,3 strains of Massilia,5 strains of Pantoea and 9 strains of Ochrobactrum collected from library respectively referred to as C18,M3,F5 and C9)all promoted the growth of wheat,compared with CK and NK;the growth of wheat root length increased by up to 196.70%,the root dry weight increased by up to 107.47%,salinity of rhizosphere soil was reduced by 49.88%treated with C18,organic matter content increased by 50.33%treated with F5,available phosphorus content increased by 21.71%treated with M3.3.Effect of 35 strains of PGPR on the wheat emergence under salt stress:after screening,9 strains of PGPR were obtained,which significantly increased the length of wheat seedlings,root and seed vigor index under salt stress;and the higher the salt concentration,the more markble growth-promoting effect was showed compared with the CK and NK.Among them,under the 300 mmol/L salt concentration,root length and seed vigor index increased by up to 1225.55%and 222.45%treated with strain 168,seedlings long increased by up to 80.27%treated with FWP0503.4.Effect of 9 strains of PGPR respectively inoculated in potted wheat,oats and canopy under salt stress:effect of growth of PGPR on the same plant is different,effect of the growth of same PGPR but different plants are also different.Among them,the SP0509 significantly increased wheat and oats,oat and canopy above ground dry weight of rhizosphere soil available nitrogen content;FYP1101 significantly increased the wheat canopy and underground part dry weight,oats and canopy rhizosphere soil organic matter content;B333-1 significantly increased wheat and oat root length and rhizosphere soil available nitrogen content.In conclusion,the desert plant rhizosphere soil is rich of PGPR strains.They have a variety of features such as nitrogen-fixation,phytate-phosphorus-solubilizing,inorganic-phosphorus-solubilizing,siderophore-producing,ACC-deaminase-producing and indole acetic acid(IAA)-producing.Among them,Enterobacter is advantage,is the most potential strains of promote plant growth under salt stress.This study provide a theoretical and practical basis for the improvement of the production performance of salt stress plants,improvement of saline-alkali land and protect the ecological environment.