Effects Of Neotyphodium Gansuense On Competition Of Achnatherum Inebrians

Drunken horse grass (Achnatherum inebrians), an intoxicating grass growing at native grassland mainly in Northwestern China, is symbiotic with endophyte of Neotyphodium gansuense. The competitive interactions among the endophyte infected (E+) A. inebrians and endophyte free (E-) A. inebrians, and Stipa capillata, Poa sphondylodes and Medicago sativa, respectively, were determined. The main results summarized as followings:1. In laboratory by seed germination of top paper (TP) method, the water extraction of the E+A. inebrians performed the significant inhibiting effects on the seed germination and seedling growth of its accompany species of S. capillata & P. sphondylodes. The inhibiting effects became greater with the increasing of the extraction concentration. However, the E-A. inebrians had no significant effects on the seed germination, only the higher concentration of 0.2 g/mL showed the inhibiting effect on the seedling growth.2. Under pot and field conditions, E+A. inebrians performed the significant inhibiting effects on the seed germination and plant growth of both S. capillata and P. sphondylodes. Compared to E-A. inebrians, E+one showed the significant inhibiting effects on the tiller height of both accompaning grasses from the 1st week after germination, on the tiller number and total biomass. Under field condition, mean species number per quadrat in E+plots was only about 62.5% of those in E- plots for the past three harvests.3. Under pot condition, the total biomass, relative yield and competitive balance index of M. sativa were significantly higher than those of A. inebrians, the relative total yield was significantly lower than 1. The relationships mentioned above become more obvious with decreasing of experimental plant community densities. Compared to those in monoculture, the total biomass of A. inebrians at the densities of 4,8 and 12 plants/pot in mixture decreased by 38.5%,41.4% and 56.0%, respectively. However, the total biomass of M. sativa at the same density between monoculture and mixture showed no significant difference. The relative competitive ability of M. sativa was higher than that of A. inebrians. It will be a promising strategy to control A. inebrians by using M. sativa as a competitor for replacement. 4. Under laboratory condition, the quantity of soil microbes and nutrient components of rhizosphere soil of A. inebrians was higher than accompanying species in Sangke, Ganjia and Yuzhong, Gansu, China.