| Plant growth-promoting rhizobacteria?PGPR?can improve seed germination rate of different plants,promote plant growth,increase leaf area and chlorophyll content of plants,increase plant biomass,root length and root surface area to a certain extent,thus accelerating plant growth process,and can also antagonize the growth of many plant pathogens and reduce the incidence of plant diseases.This experimental study mainly aims to screen plant rhizosphere-promoting bacteria?PGPR?with high phosphate-dissolving,potassium-dissolving,IAA-producing,HCN-producing,iron-producing carrier,and ACC deaminase-producing activity,from plant rhizosphere and 100 strains of life-promoting strains were isolated and screened from rhizosphere soil.Then,22 strains had phosphate-dissolving activity,11 strains had potassium-dissolving activity,9 strains had IAA-producing ability,and 16 strains had 16strains.The ability to produce iron carriers,one strain has the ability to produce ACC deaminase.Twenty strains with higher life-promoting properties were selected for physiological and biochemical characteristics determination and 16srDNA sequencing.The growth promoting effects of these 20 strains were initially determined by plate hydroponics.The results showed that the best promoting effects were 2-2,3-1,5,22-2,30-4.The pot experiment showed that the experimental group with bacteria increased the barley biomass compared with the control group.The strain with phosphorus-dissolving activity could increase the available phosphorus content of barley,and the strain with potassium-dissolving activity could increase the available potassium content of barley.The results showed that strain 30-4 promoted the life more than other strains,optimized the medium conditions,and optimized the conditions by single factor experiment and response surface optimization:0.29%beef extract,1%yeast extract,0.78%MgSO4.The IAA output after optimization was 106.11 mg/L,which was 23.4%higher than that before optimization. |
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