| Phosphorus is one of the essential mineral elements for plant growth,and it is easy to be fixed in soil.The phosphate solubilizing microorganisms can convert the phosphorus which is difficult to be absorbed into the form of absorption and utilization through the metabolism and the product.It is of great significance to study the mechanism of microbial phosphorus removal.Firstly,the effect of different organic acids on the dissolution of tricalcium phosphate was studied.Oxalate and other 10 kinds of organic acid applied to calcium phosphate inorganic phosphorus culture medium 6 D,determination of available phosphorus content in medium and orthogonal experiments on 5 kinds of organic acids with strong ability to dissolve tricalcium phosphate.Then,the selection of rhizosphere bacteria preserved red dates of Xinjiang Agricultural University Forestry Research Institute for experimental materials.In order to study organic acid secreted from phosphorus-solubilizing bacteria and calcium phosphate dissolving ability.The P7,P13,P15,P18 phosphate-solubilizing bacteria were sent to cultivate.Finally,in order to study the effect of phosphate-soiubilizing bacterial in rhizosphere soil of jujube on the contents of organic acids and available phosphorus in soil.The P7,P13,P15 and P18 strains with strong ability of phosphorus solubilizing were cultured in vitro and then applied to the rhizosphere of jujube.The number of viable bacteria,available phosphorus and organic acid in soil were measured.The main results are as follows:(1)All 10 organic acids could promote the dissolution of tricalcium phosphate,but their ability to dissolve phosphate was significantly different.Oxalic acid,tartaric acid,pyruvic acid,lactic acid and acetic acid five kinds of organic acids have the strongest ability to dissolve phosphorus,the ability of malic acid and alpha glutaric acid is weak,propionic acid,fumaric acid,citric acid was the weakest.The results of orthogonal tests on 5 kinds of organic acids with strong ability to dissolve phosphorus showed that their ability to dissolve tricalcium phosphate was: tartaric acid > pyruvate > lactic acid > oxalic acid > acetic acid.(2)The organic acid types and content is determined by high performance liquid chromatography(HPLC)method,carries on the dynamic observation and study the relationship between phosphate-solubilizing and organic acids.Research shows that the content difference of four kinds of bacteria producing organic acids is very big,and organic acids produced by the same bacteria at different times are also different.Research shows that the ability of four kinds bacteria dissolved tricalcium phosphate capacity have obvious difference,the size of the order is: P15>P13>P18>P7.Effects of strains and their metabolites,the direct effect of organic acids on available phosphorus in the liquid was different from that in(1).Through the path analysis found direct effects of organic acids on available phosphorus in descending order are: pyruvic acid>tartaric acid> lactic acid>acetic acid> oxalic acid.From the experimental analysis,the strongest ability to solve phosphorus bacteria are P15 strains and the direct effects of pyroracemic acid on the dissolution of calcium phosphate is the strongest.(3)On the 30 day of 4 kinds of solubilizing strains have good colonization ability.The results showed that 4 kinds of phosphate-soiubilizing bacterial could increase the content of available P in soil and it can also increase the content of pyruvic acid,acetic acid and lactic acid.Through comprehensive analysis,it was concluded that P15 and P18 strains had the best effect of dissolving phosphorus in field.The organic acid produced by bacteria is one of the important factors of dissolved phosphorus. |
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