Effects Of Arbuscular Mycorrhizal Fungi On Uptake Of Organic Nitrogen In Elymus Nutans

High elevation and low temperature limit the mineralization of organic matter, as a result that there are more amino acid in the soil than mineral nitrogen(NH4+、NO3-) in the qinghai-tibet plateau area. Mycorrhiza symbionts greatly promote absorption and utilization of nitrogen, and mycorrhizal fungi is an important way of nitrogen uptake in plants. In order to explore growth and physiological effects of Elymus nutans in different nitrogen source, we applied arbuscular mycorrhizal fungi(AMF) in Elymus nutans throμgh quartz sand without any nutrients. The results indicate that(1)The absorption of glutamic acid in Elymus nutans was stronger than that of aspartic acid and glycine. When glutamic acid was the only source of nitrogen, commercial Beijin Elymus nutans(BJ) was the weakest and wild type Shenzha Elymus nutans(SZ) was the strongest in absorption of nitrogen, and the appropriate amino acid concentration was 2.0 mmol/L.(2) When organic nitrogen or inorganic nitrogen was the separate source of nitrogen, all the inoculated roots were colonized, and colonization rate of two Elymus nutans increased firstly and then decreased. Application of AMF could increase total root length and surface area, and improve root activity in Elymus nutans. Mycorrhizal inoculation could increase above-ground biomass of Elymus nutans, and wild SZ had a bigger increase.(3)When organic nitrogen or inorganic nitrogen was the separate source of nitrogen, application of AMF could improve above-ground biomass, contents of carotenoid, total nitrogen, total free amino acid, soluble protein and nitrate reductase activity. But it might not functional or be opposite effects in chlorophyll a/b, contents of nitrate nitrogen and glutamine synthetase activity of the plants.(4) When organic nitrogen was the source of nitrogen, Two Elymus nutans were stressed to some extent, and BJ was weaker in its growth. Application of AMF could decrease electrolyte leakage rate and malondialdehyde(MDA) content. It also decreased the activity of superoxide dismutase(SOD), catalase(CAT) and Peroxidase(POD)in Elymus nutan.In conclusion, there is not obvious difference between application of inactive AMF and none AMF. Application of active AMF improves biomass of plant and uptake of nitrogen, and reduces hurt of organic nitrogen which is the only nitrogen in the growth of Elymus nutans.