Abstract:This study was conducted to investigate changes of seed germination, seedling morphological and physiological indexes of endophyteinfected (E+) and endophytefree (E-) perennial ryegrass (Lolium perenne) in latosols extracts solution with different pH(4.47-6.12)by using the laboratory germination experiment, to analyze the effect of the endophytic fungi on seedling growth and physiological characteristics of ryegrass in an acidic environment. The result showed that: (1) in the same endophyte infection[endophyteinfected (E+) or endophytefree (E-)] of case, the germination rate, germination energy, germination index, vigor index of seeds, shoot length, root length, fresh weight and dry weight of seedling showed a decreasing trend with the decrease of latosols extracts solution pH value (the acidity of the extracts is enhanced), and the treatments of five latosols extracts solution were significantly lower than that of CK (pH, 6.12) (P <0.05); proline content, superoxide dismutase activity (SOD), peroxidase activity(POD), and malondialdehyde content (MDA) of ryegrass had minimum value under pH 6.12, and were significantly lower (P <0.05) than that of other five treatments of latosols extracts solution. (2) In addition to the control (CK), endophyteinfection significantly (P<0.05) improved germination rate, germination energy, germination index, vigor index, shoot length, fresh weight, dry weight, proline content and SOD activity, and decreased the POD activity and MDA content under pH 4.47-5.01. In the acid latosols extracts solution, the root length of perennial ryegrass that endophyteinfected (E+) had no significant difference (P>0.05) with endophytefree (E-) when the acid latosols extracts solution pH 4.47-6.12.The results showed that the effects of latosols extracts solution with different pH on seed germination, growth and physiology of endophyteinfected (E+) and endophytefree (E-), and endophytic fungi improved the growth and adaptive capacity of host in wider pH of latosol extraction. The symbiont of perennial ryegrassendophytic fungi can be used for improving acid soil.