The Screening Of Phosphorus Strains And Its Influence On Wheats

This study began from screening microorganisms which can transform insoluble phosphorus into soluble one.First,19 microbial strains from the soil of Dalian Academy of Agricultural Sciences were separated through preliminary screening.Then rescreening was done using broth assay method.According to the ability of phosphorus solubilization,C2' was selected with phosphate-dissolving ability of 557.68 mg/L.In the phosphate-solubilizing process,the pH of C2' medium fell to 3.19.Through morphological observation and scanning electron microscope analysis,C2' was found to be fungus.PCR amplification analysis showed its nucleotide sequence was 630 bp and the GenBank Accession Number is EU434727.Homological analysis showed that gene sequence had a high homology to Penicillium oxalicum strain ZH30-99%,Penicillium oxalicum-100%,and Penicillium ochrochloron strain UWFP 720-95%,indicating C2' was Penicillium oxalicum.Then,the testing for the effect of different carbon,nitrogen and salt concentration on mineral phosphorus medium was carried out.The organic phosphorus-sulubilizing ability was also studied.Preliminary mechanism of phosphorus solubilization was studied by High Performance Liquid Chromatography method.First,the separated condition was optimized.The different standard organic acids and the microbial zymotic acids can be separated better when the mobile phases were following:A,0.1 mmol/l potassium dihydrogenphosphate buffered at pH 2.60 with orthophosphoric acid and B,100%methanol.All procedures were carried out using isocratic elution with 100%mobile phase A.The flow-rate was 0.7 ml/min.The chromatographic column was thermo stated at 25℃.Retention time of each signal was recorded at a wavelength of 214 nm.The results showed that C2' produced eight kinds of organic acids(4 were unknown).And in its medium,oxalic acid content was 32.14 mg/L, tartaric acid content 218.23 mg/L,malic acid content 487.46 mg/L and lactic acid content 5.57 mg/L.At last,the practical phosphorus-solubilizing ability of C2' was studied.A detailed experiment about the effect on wheat growth was carried out.Compared to the wheat without C2',the wheat with C2' had the following improved results:the length of root increased by 31.25%,the weight of root increased by 28.33%,the plant biomass increased by 16.67%,the root phosphorus concentration increased by 32.46%,and the shoot phosphorus concentration increased by 28.02%.The concentration of soil soluble phosphorus also increased by 1.77%, after 28 days of wheat cultivation.