Effects Of AM Fungi On The Growth And The Drought Resistance Of Bermuda Grass Under Different P-applied Levels

With the critical issue of water shortage growing all over the world, water conservation and drought resistance have attracted close attention. Mycorrhizal fungi (MF) are important soil microbes that form mycorrhizae with host plant roots of more than 90% terrestrial species. Arbuscular mycorrhizal fungi (AMF) are most studied species. AMF has selectivity but no specificity on the host plant. The symbiosis can help promote soil mineral elements absorption of host plants, regulate internal metabolism activity, improve physical and chemical properties of soil and improve stress tolerance of plants. Meanwhile, AMF also absorb necessary nutrients from host plants. Ecological conditions have influences on AM fungi colonization to host plants, such as soil phosphorus. Phosphorus is one of the indispensable nutrients on plant growth. However, soil in our country is deficient in phosphorus and the available phosphorus of quite a few soils is less than 10 mg/kg. Currently, as a potential biological phosphorus fertilizer, AM fungi have been extensive studied. Their application has great potentials on promoting plants growth, reducing fertilizer consumption and improving stress tolerance of plants in sustainable agricultural production systems.Bermudagrass (Cynodon dactylon (L.) Pers. cv. Banama) is a kind of perennial warm season grass with developed stolons and rhizomes, widely distributing in warm semi-humid zone and warm wet zone in the world. Bermudagrass has been used widely in landscaping and sports field for its ecological characters and easy to manage.Pot experiment was conducted to study the related effects of AM fungi and P-applied levels on growth and drought resistance of Bermuda grass, and physical and chemical properties of soil. This might provide the basis for AM fungi in the application of Bermudagrass. The main results are as following:Glomus mosseae (GM) and Glomus aggregatum (GA) both formed favorable symbiosis with Bermudagrass. Under the three P-applied levels, GM and GA inoculation significantly increased AMF colonization at 0.04gP/kg soil level, and effects of GA were better than those of GM. AMF colonization was lower at 0.1gP/kg soil level than 0.02gP/kg soil level, indicating that high phosphorus level might restraint AMF colonization. AMF had selectivity on the host plant. Under AMF (GA, GM, GA+GM) inoculation, AMF colonization in plant roots inoculated with GA or GM were higher than those inoculated with GA+GM, and AMF colonization of GA was higher than GM. Meanwhile, the effects of GA or GM inoculation were better on growth and drought resistance of Bermudagrass than GA+GM. We concluded that inoculation of single AMF may be the best treatment for improving growth and drought resistance of Bermuda grass.Under normal water condition, inoculating with single AMF at 0.04gP/kg soil level improved the growth of Bermudagrass, promoted P and N absorption and accumulation in the root system。Under water drought condition, inoculating with single AMF at 0.04gP/kg soil level increased the contents of chlorophyll(Chl) and leaf relative water (LRWC), affected activities of superoxide dismutase (SOD) and catalase (CAT) and the contents of osmotic regulation substances-soluble sugar (SC). The content of malondiadehyde (MDA) under this P level directly proved that single AMF inoculation alleviated the peroxidation degree of membranous lipid of plantlets, and protected the plasma membrane and promoted drought resistance of Bermudagrass. Moreover, content of RPP under this level was lower than other levels, indicating directly that the damage of membrane under this level was less than that in other levels, which increased drought resistance of Bermudagrass...