Study On The Effects Of Microorganisms On Phosphorus Transformation In The Rhizosphere Of Wetland Plants

Species and abundance of wetland plant rhizosphere microorganisms have an impact on the phosphorus interception of wetland plants. In this article, the Yeyahu wetland was studied as the carrier, three typical speices of emergent plants, such as Scirpus planiculmis, Phragmites australis and Zizania aquatic were sampled and under monitored in the field experiments, the seasonal distribution of microbial community structure, distribution of different forms of phosphorus and the effects of microorganisms on phosphorus transformation were detected.The results proved that:rhizosphere microbial biomass was mainly affected by the region, the growth of the plants and the seasonal changes. The total PLFA contents of rhizosphere soil were more than the one of non-rhizosphere soil, and the contents of bacteria in Summer were highest. The average TPLFA content of rhizosphere ranged from 34.93 to 40.65 nmol/g, content of non-rhizosphere ranged from 23.77 to 29.27 nmol/g. The main bacteria ratios ranked in the order of bacteria> fungi> actinomycetes. In rhizosphere soil of three plants, mean proportion of bacterial at about 65%, and the mean proportion of fungi at about 8%. The ratio of bacteria/fungi was mainly affected by the plant growth. The ratio in rhizosphere reached a peak in July because of root activity. The ratio of G-/G+ showed a significant decrease trend with the nutrient level of soil was decreasing. The ratio of special fatty acid was mainly affected by plant growth and soil nutrient. This value peaked in vigorous growth period of plants, indicating that microorganisms were under nutritional pressure. The predominant bacteria were aerobic bacteria with 16:0 as the representative whether in rhizosphere or non-rhizosphere soil, and the rhizosphere content was higher.Different species of phosphorus were affected by the plant growth and the utilization of IP by plants may lead to the mineralization of OP in the July or August.The TIP content of rhizosphere was less than the one of non-rhizosphere, while the TOP content of rhizosphere was higher than the one of non-rhizosphere. TOP content of rhizosphere ranged from 107.76 to 232.50mg/kg, TIP content of rhizosphere ranged from 178.66 to 307.16mg/kg.The OP and IP contents were both accumulated in the decline phase. The overall order of OP content was:HR-OP>MR-OP-ML-OP>L-OP, the overall order of inorganic phosphorus content was:Ca-P>Oc-P>Fe-P>Ex-P>Al-P.The relationship between microorganisms and phosphorus may be mainly affected by plant growth conditions. Both the TPLFA content and bacteria content had a negative correlation with many species of phosphorus, which suggested bacteria play an important role in phosphorus transformation and can make a use of HR-OP, Oc-P and Ca-P. The correlation between SMBP and various forms of phosphorus indicated the SMBP play an important role in soil phosphorus cycle.