Effects Of Neotyphodium Endophyte And AM Fungi On Growth Of Hordeum Brevisubulatum Under Salt And Phosphorus Stress Conditions

Neotyphodium/Epichloe endophytes not only confer enhanced fitness, but also have the positive effect on stress tolerance and plant growth of the host grass. Arbuscular Mycorrhizal Fungi (AMF) can improve the mineral nutrition especially P uptake and storage in the plants. Both symbionts of Neotyphodium endophyte and AMF in wild barley (Hordeum brevisubulatum) were studied under different conditions of normal, salt (0,200,400,600mmol/L NaCl) and phosphorus (0,0.05,2mmol/L P) stresses, with four treatments of both endophyte infected (M+) and AMF infected (M+)(M+E+), only AMF (M+E-), only endophyte infected (M-E+) and non fungi (M-E-). The main results were summarized as followings:1. Under the normal conditions, AMF infection and colonization in H. brevisubulatum were significantly inhibited by the Neotyphodium endophyte (P<0.05), the inhibition rate was41.67%. The above-ground and total biomass of the grass were significantly increased by both grass endophytes and AMF, while the root biomass was significantly increased by AMF (P＜0.05), but not endophyte. The accumulation of nitrogen (N) and phosphrus (P) in host grass showed that the contents of total N in the treatments with only endophyte or AMF infected alone was significantly higher than those of with both fungi infected, respectively (P＜0.05). P absorption and accumulation caused by AMF were inhibited by the endophyte as well.2. Under the salt stress condition, the shoot biomass of the M+E+and M-E+treatments were increased significantly (P＜0.05), and the root and total biomass of the M+E+, M+E-and M-E+treatments were significantly (P＜0.05) promoted under200mmol/L NaCl solution..Under400mmol/L NaCl solution, both endophyte and AMF had positive promotion to its host plant (P＜0.05), however, there was no significantly diferencees among them under600mmol/L NaCl. With increasing of NaCl solution, the shoot N content in the plant increased then decreased, but root N and P decreased. But the content of N in root and P tended to be decresed. Under200mmol/L NaCl, endophyte could significantly increase absorption of shoot N (P＜0.05), AMF could significantly increase absorption of shoot and root P.. However, there was not significant promotion effect by endophyte and AMF co-existed.3. Under treatments of high P (2mmol/L KH2PO4, Hp), low P (0.05mmol/L KH2PO4, Lp) and non-P (0mmol/L KH2PO4, Op) conditions, compared with non-fungal treatment, only endophyte (M-E+) could significantly improve plant height and tiller numbers (P＜0.05), dual infection (M+E+) significantly increased shoot and root biomass of plant (P＜0.05). Under Op level, M+E+and M+E-had significantly more root biomass than those of under other treatments (P＜0.05). Under the Lp level, both M-E+and M+E-increased the content of N and P accumulation in host plants (P＜005).