Comparison of fungal community parameters and soil fertility of ten macrophyte rhizospheres

【Objective】 Constructed wetlands(CWs) are often used for treating wastewater from point sources. Macrophytes and their rhizosphere microbes are the most important components in CW systems. Researches have mainly focused on the structure and functions of bacterial communities in CWs, but less on information of fungal communities. This study investigated soil fertility, fungal number, biomass and the carbon metabolic profiles in rhizosphere soils of 10 aquatic plants. The objectives are to select the plant species with greater fungal biomass and higher activity and to provide evidences for better wetland development. 【Methods】 The sampling sites were selected randomly by throwing a piece of stone backwards, and soil samples were collected from macrophyte rhizosphere. Soil organic carbon, total nitrogen and phosphorus contents were determined by using potassium dichromate titration method, Kjeldahldigesting method and Mo-Sb-ascorbic acid spectrophotometric method, respectively; soil fungal number was measured using plate counting method; fungal biomass(i.e. ergosterol content) was measured using high performance liquid chromatography(HPLC) method, and the carbon metabolic profiles of soil fungal communities were analyzed using FF microplates. 【Results】 Acorus gramineus, Typha latifolia and Iris pseudacor rhizosphere soils had higher organic carbon, total nitrogen and total phosphorus content than other plant species respectively (P 0.05). Iris pseudacor rhizosphere soil had greater fungal number and biomass(P 0.05). Correlation analysis showed that the total phosphorus was significantly and positively correlated with the fungi number and biomass(r=0.59 and 0.47 respectively, P0.05), thus it is an important factor that affects soil fungal distribution. The carbon metabolic fingerprint analysis indicated that the capability of soil fungi community to utilize 95 carbon sources and 6 carbon groups in Canna generalis rhizosphere soil was higher than those in other plant rhizosphere soils. Soil total nitrogen content significantly influenced the capacity of fungal communities to utilize the carbohydrate group(r=0.38,P0.05). 【Conclusions】 There was a significant difference in soil fertility and fungi community parameters among the 10 macrophyte rhizosphere soils, so soil fertility and fungi community parameters can be used as the bases for screening macrophytes for construction. However, the fungal species, community structure and diversity need to be further studied from molecular technologies perspective in the future.