Abstract: Leymus chinensis and Stipa krylovii, two dominant species in the Inner Mongolia Steppe, were used as the experimental materials. The aim of this study was to test whether endophyte infection of L.chinensis would influence seed germination of S.krylovii when treated with organs in vitro or the whole plant. The results showed that endophyte infection could change the effects of host plant L.chinensis on seed germination of S.krylovii, the effect was related to grass organs, treatment methods and concentrations. Compared with endophyte-free (E-) leaves, endophyte-infected (E+) green leaves significantly increased seed germination rate of S.krylovii in lower concentration while decreased radicle growth of S.krylovii in higher concentration. E+ dead leaves could reduce radicle growth of S.krylovii more than E- leaves while E+ rhizome increased the germination rate more than E- leaves. As for the whole plant, endophyte infection had no significant effect on seed germination of S.krylovii. When treated with the same concentration, grass powder exhibited a stronger reduction in seed germination and seedling growth than water extract, and green leaves exhibited a stronger reduction in seed germination and seedling growth than dead leaves.

Key words: endophyte, Leymus chinensis, Stipa krylovii, seed germination