Study On Phosphate Solubilizing Characteristics,Phosphate Solubilization Mechanism And The Growth Promoting Effect Of Penicillium Funiculosum P1

Phosphate-soluble bacteria play an important role in the transformation of phosphate in soil.Generally,phosphate-soluble bacteria can transform the insoluble phosphate that cannot be absorbed by plants into soluble forms,thus providing effective phosphate for plants growth and development.In this study,a high-efficiency phosphate solubilizing strain?Penicillium funiculosum P1?preserved in our laboratory was used as the research object to explore its phosphate solubilizing characteristics,mechanism and promoting effect on seed germination.This study provides a high-quality strain for the development of high-efficiency phosphate fertilizer,and may provide theoretical basis for solving the issues of soil hardening caused by the application of phosphate fertilizers and the serious imbalance of nutrient ratio in the soil.The results are as followed:1.When the additional amount of calcium phosphate was 7 g/L,Penicillium funiculosum P1 had the best effect on dissolving phosphate,and the amount of dissolving phosphate reached to 1120.52 mg/L.Strain P1 had a wide adaptability to carbon and nitrogen sources,and had less influence on the phosphate solubilizing ability.When glucose,sucrose and soluble starch were used as carbon sources,the amount of dissolved phosphate could reach more than 1000 mg/L;and the amount of dissolved phosphate could reach to 882.78 mg/L with the carbon source of lactose.When ammonium sulfate,ammonium chloride,potassium nitrate and sodium nitrate were used as nitrogen sources,the amount of dissolved phosphate was over 1000 mg/L;and the amount of dissolved phosphate was 839.47 mg/L with the nitrogen source of ammonium nitrate.In addition,strain P1 had strong solubility to calcium phosphate,but poor solubility to iron phosphate and aluminum phosphate.The experimental results showed that the phosphate dissolving mechanism of strain P1 was mainly by hydrogen ion and supplemented by organic acid.Strain P1 could secrete phosphatase to dissolve organic phosphate.Phosphatase is only active from 0 to 96 h,and alkaline phosphatase activity is higher than acid phosphatase activity.2.Strain P1 still had a strong ability of dissolving phosphate in a high concentration of soluble phosphate.Under the stress of Pb²⁺and Cr⁶⁺,strain P1 has a good ability to dissolve phosphate and has a better ability to remove them;The ability of dissolving phosphate was suppressed in the stress of Zn²⁺,but it still had a certain ability to remove Zn²⁺.Strain P1 has a strong ability of dissolving phosphate under the condition of low concentration of Ni²⁺and has a good ability to remove it,while strain P1 hardly grow with the high concentration of Ni²⁺.Strain P1 had no ability to solubilize phosphate under Cu²⁺stress.Moreover,the ability of dissolving phosphate of strain P1 was still strong under drought stress,and the amount of dissolving phosphate could reach to 418.85 mg/L.Strain P1 could grow at 10??35?and had the ability of dissolving phosphate.The amount of dissolving phosphate is 34.67 mg/L at10?and 364.97 mg/L at 35?.3.Strain P1 could secrete iron carriers and indoleacetic acid.The results showed that strain P1 had a better growth promoting effect on corn,mung bean,sorghum and wheat seeds,but no obvious growth promoting effect on rice seeds,and a significant inhibitory effect on melon seeds.