| Red soil is a typical soil resources in South China, Available phosphorous in Phosphate fertilizers was transformed readily to unavailable phosphorous by the high content of iron and aluminum in red soil, thus reducing fertilizer utilization efficiency. Most of soil that lack of phosphorus for crops is due to the phosphorus in soil often in the status not easily absorbed by plants directly, although there is a lot of total phosphorus in soil. Accordingly, crops often grow poor if not any phosphorus supplied. Phosphorus is one of the most essential elements for plant growth, employing phosphorus fertilizer is a very crucial management to increase crop yields. Many studies suggested that there is a huge number of PSM in the rhizosphere soil of plants, which can solubilize sparingly insoluble Phosphate into available phosphorus that can be easily utilized by crops, and decrease absorption and immobility of Phosphate in soil, and avoide environmental pollution caused by slathering phosphorus fertilizer. Therefore, it is very important for agricultural sustainable development that screening high efficiency PSM as inoculant to manufacture biofertilizer, and is helpful to reduce dosage quantity of phosphorus mineral fertilizer.This reseach was conducted to isolate and screen PSM from the rhizosphere soil of peanut growing on the red soil with a Long-term fertilization. Three strains with high Phosphate solubilizing ability were obtained, Identification and Characteristic of P-solubilizing as well as their growth promotion effect were done, and the results are as follows:The long-term organic fertilizer treatment could increase bacteria and fungal CFUs, Balanced fertilizer treatment increased bacteria and actinomycetes CFUs compared to imbalanced fertilizer treatment, the least soil cultivable microbial CFUs was found in inorganic fertilizer NK (lack of P element) treatment.A total of xixteen strains of PSM were isolated on PVK plate, three of which showed the highest Phosphate solubilizing ability in NBRIP liquid culture, namely B1-A, B1-C and C5-A respectively. According to their biophysical and biochemical characterisrics and16S rDNA and ITS rDNA sequence analysis, strain C5-A and B1-A and Bl-C were identified as Burkholderia cepacia, Aspergillus niger and Penicillium sp., respectively, accordingly gene bank number is JX036483.1and JX036484.1and JN571420.1.The characteristic of P-solubilizing of three strains is quite different though they all showed high ability to dissolve aluminium Phosphate and ferric Phosphate.Phosphate solubilization capacity and pH of the medium were strongly affected by culturing time and initial inoculation level, the dynamic variations of Phosphate solubilization capability and pH in both aluminium Phosphate and ferric Phosphate cultures during solubilizing period at three inoculation levels indicated that the Phosphate solubilization capacity was closely correlated to the drop of medium pH, Besides, Phosphate solubilization capability was also related with the origins and the concentration of RP, all three strains have a high ability for solubilizing both Jiangxi and Yunnan RP and they seemed to be more efficient in solubilizing Yunnan RP than Jiangxi RP.In liquid medium, Phosphate solubilizing ability of three strains was affected by different carbon and nitrogen sources. The result suggested that the highest P solubilization capacity exhibited when maltose and Ammonium oxalate served as C source and N source respectively followed by Glucose and Ammonium sulphate, the effect of different N sources on the categories and content of organic acids released were also detected by HPLC. The results indicated that the categories and content of the organic acid were quite different for each isolate and the most categories of organic acid was detected out when urea served as N source while the least number of organic acid was detected out when potassium nitrate served as N source. Oxalic acid, Acetic acid, Malic acid, Lactic acid, Citric acid and Succinc acid were not the key factor on determing P solubilization capacity.Growth promotion effect of three PSM on peanut and Phosphate solubilizing ability under soil codition were studied by using pot culture experiment. The results showed that all the strains could promote plant growth and increase the content of phosphorus in both plant tissue and soil to a certain extent, the strain C5-A had a significantly effection on increasing total phosphorus in both plant tissue and soil though its growth indexes such as fresh weight, dry weight, plant height, root lenghth and branch number promoting effect is the least.It is concluded that three strains with high P solubilization ability and plant promotion effect from red soil under long-term different fertilization were obtained, which are promise microbial resources for development of high efficiency biological phosphorus fertilizer for latosolic red soil. |
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