Study On Effect Of Arbuscular Mycorrhizal Fungi On The Function Of Ecological Floating Bed

With the rapid urbanization development, control of surface water pollution in urban has become a problem that we must face. Under the facts that the land resource is scarcer and scarcer and human population is more and more in urbans, the traditional water treatment technologies, such as artificial wetland, encounter more and more difficulties. Ecological floating bed technology (EFBT) has many advantages, including little occupying soil land, little affected by water level fluctuation, convenient management, economical and high efficiency, and landscape function. Recently, EFBT has attracted much attention and plays important roles in remedying surface water pollution in domestic and foreign cities. However, plants of EFBT often encounter environmental stresses, pollution plant diseases and insect pests because EFBT is generally used in polluted environment. It is important how to increase tolerance and resistance of EFBT plants to environmental pollution stresses and promote EFBT plants growth because this can enhance the EFBT function. AM fungi generally exist in wetland environment and have positive effects on growth, nutrition and tolerance/resistance to environmental stresses of wetland plants. Therefore, we will study effects of AM inoculation on EFBT plants tolerance/resistance to water pollution and EFBT function. In addition, AM formation is significantly affected by phosphorus concentration, while phosphorus concentration is generally high in of urban surface water, so we also concern effect of phosphorus concentration in water on AM formation of AM in EFBT plants.Experiment about effects of water phosphorus concentration on AM formation in EFBT plants showed that:(1)AM formation in Canna indica, Cyperus alternifolius, Typha minima were not affected by low phosphorus (<5mg·L-1), but mycorrhizal colonization rates (MCR) of were significantly reduced by high phosphorus concentration (9 mg·L-1), and the MCR in three EFTB was the lowest under the high phosphorus concentration,was lower than that of the maximum value of low phosphorus by 40.0%,27.7%,1.3% respectively; (2) AM increased growth of three EFBT plants, especially for Canna indica and Cyperus alternifolius; (3) AM fungi colonization to its host plants varied with plant species, and produced different effects on plant growth.Experiment about effects of AM fungi on floating bed plants tolerant to heavy metal stress indicated that:(1) symbiotic association was well established between AM fungi and cattail roots, and MCR was beyond 30%. However, MCR presented downward trend one month after mycorrhizal cattails were transported to solution, and the maximal decrease was 25.5%; (2) AM increased pigment concentrations and peroxidase (POD) activity in cattail leaves, and also increased roots radial oxygen loss. However, AM only produced significant effect on increase of fresh weight in 5 mg·L-1 Cd2+ solution; (3) although plant growth was inhibited by 5 mg·L-1 Cd2+ and MCR was lower, AM increased Cd uptake of cattail in the two Cd2+ levels, and the maximal increase was 40.2% and 56.5% in aboveground and underground parts respectively.Experiment about effect of AM inoculation on application of EFBT in domestic sewage treatment showed that AM fungi increased the removal rate of COD, TN, TP and NH4+-N by EFBT. Relative to non-mycorrhizal EFBT, the removal rates of these four parameters increased by 11.7%,12.9%,8.1% and 14.1%, respectively. The positive effects increased with increasing time, and the greastest increment was 15.6%(8d),16.1%(6d),16.9%(7d) and 14.1%(4d).