The Characteristic Of Phosphorus Dissolution Of A Salt-tolerant And Alkaline-tolerant Phosphate-solubilizing Bacteria And The Effect On Physical And Chemical Properties Of Saline-alkaline Soil

Phosphorus is one of the essential elements for crop growth.It is reported that soil phosphorus deficiency is very serious in China,and about 74% of the cultivated soil is deficient in soil,which contains a large amount of ineffective phosphorus.The full use of soil in the difficult soluble phosphate is the key to solve the problem of soil phosphorus deficiency.Phosphorus-solubilizing bacteria is a microorganism that converts refractory phosphate into soluble phosphate.Therefore,the related research of phosphate-solubilizing bacteria is of great significance to the application of soil insoluble phosphorus,the solution of soil phosphorus deficiency and the sustainable development of agricultural production.Saline soil has a high salt and pH,fertility barren,not only seriously affect the growth of crops,but also seriously threat the ecological environment.Therefore,it is of great significance to seek efficient salinity soil improver for the improvement of saline soil,agricultural production and ecological environment protection.In this paper,we investigated the classification of phosphate-tolerant bacteria and the characteristics of dissolved phosphorus,and explored a modified agent for saline soil in Gansu Province.The following test results were obtained:1.The method of halo ring was applied to isolate the phosphate-solubilizing bacteria,the method of Mo-Sb colorimetry was applied to measure phosphorus-dissolving ability.D/d> 1.6,which are C9-41,Y3-35,C5-411,C5-410 and Y3-51 strains,among which strain Y3-35 has the best ability to dissolve phosphorus(P<0.05).The maximum phosphorus-dissolving ability could be up to 206.06 mg/L.The phosphorus-dissolving ability of strain Y3-35 showed a negative correlation with pH.2.Salt tolerance were tested by beef extract peptone medium of different NaCl gradient concentrations.Alkali tolerance were tested by beef extract peptone medium of different p H gradient.The genetic stability was determined by subculture.The quantity of dissolved phosphorus and pH of Y3-35 was kept around(163.06±8.27)mg/L and 4.92±0.10 after 20 times serial subcultivation,which indicated that the strain had a good genetic stability.The strain can grow under the condition of NaCl content?10%,7?pH?12.3.The morphological characteristics,physiological and biochemical characteristics,and 16 S rRNA gene sequence of strain Y3-35 were analyzed.The result of identification revealed that phosphate-solubilizing strain Y3-35 can be classified as Pantoea aff.theicola.4.The single factor experiment and the orthogonal experiment were applied to find optimal phosphorus-dissolving condition of strain Y3-35.The result of the orthogonal experiment indicated that the optimal phosphorus-dissolving condition of phosphor bacteria Y3-35 was as follows: glucose 20.0 g/L,peptone 15.0 g/L,NaCl 2.5 g/L,24 °C,other with the original medium.5.Using suspension of phosphorus-solubilizing bacteria(bacterial suspension: soil=1 ml: 12 g),gypsum(phosphogypsum: soil=1 g: 100 g)and cow dung cooked(dung cooked: soil=1 g:100 g),through single and combined application,the effect to amendments on soil enzyme activities,chemical properties and growth indexes of corn in saline-alkali soil was studied,the improvement effect of different amendment treatments was assessed to saline-ailkali soil.Compared with the control group(CK),the other groups also showed different improvement effect(P<0.05).The result in composite score of principal component analysis was the group which were applied phosphogypsum and cow dung cooked and bacterial suspension(PNJ)> the group which were applied cow dung cooked(N)> the group which were applied phosphogypsum and cow dung cooked(PN)> the group which were applied cow dung cooked and bacterial suspension(NJ)> the group which were applied phosphogypsum and bacterial suspension(PJ)> the group which were applied phosphogypsum(P)> the group which were applied bacterial suspension(J)> the control group(CK)> the control group which were not planted corn,the result was consistent with evaluation growth index of corn.The results shows that the group which were applied phosphogypsum and cow dung cooked and bacterial suspension(PNJ)was the most obvious group on improvement effect to saline-ailkali soil.Its soil pH and conductivity decreased 5.0% and 17.0% respectively,compared with control group.Soil effective phosphorus,available potassium,nitrogen and organic matter increased 586.1%,94.8%,22.3%,89.9% respectively,compared with control group.Soil urease,alkaline phosphatase,neutral phosphatase and acid phosphatase increased 231.4%,24.2%,175.3%,42.8% respectively,compared with control group.The result indicates that Y3-35,an highly effecient phosphate-solubilizing bacteria which has a strong saline alkali characteristics,might act as a potential candidate for the application,and provide strain support for the application of phosphate-solubilizing bacteria in saline-ailkali soil.The improvement effect of amendment that was applied in the group of PNJ to saline-ailkali soil is the best,and it has potential applications in the saline-ailkali soil ecological amendment.