Effects of fermentation broths of Epichloë sinensis endophyte strains on Elymus nutans seed germination

Three different Epichloë sinensis endophyte strains isolated from three different seed lots of Festuca sinensis collected from Gansu (1), Qinghai (41D), and Sichuan (111) in China were employed to study their effects on germination of Elymus nutans seeds and growth of roots and shoots. The effects of fermentation broths containing different concentrations (20%, 60%, and 100%) of these three different E. sinensis strains on the germination response of E. nutans seeds were evaluated. The fermentation broths had varying effects on seed germination and seedling growth. Promotion or inhibition of germination of E. nutans seeds was related to broth concentration. With 20% endophyte fermentation broth, strain 111 inhibited seed germination. With 60% and 100% endophyte fermentation broths, all three E. sinensis strains promoted germination of E. nutans seeds. Their germination force and germination index were significantly higher than the same concentrations of potato dextrose broth (P < 0.05). Strain 41D had the highest promotion effects. Using potato dextrose broth, all the tested indices of E. nutans seeds decreased with increasing broth concentration. Using 100% 41D endophyte fermentation broth, the germination rate, germination force, germination index, and vigor index of E. nutans seeds were significantly lower than values obtained at the other two concentrations (P < 0.05). However, the germination rate, germinative force, and germination index of E. nutans seeds treated with 60% concentration of 111 endophyte fermentation broth were significantly higher than with the other two concentrations (P < 0.05). Using 100% 111 endophyte fermentation broth, the radicle length of E. nutans seedlings was significantly lower than that at the other two concentrations (P < 0.05). These differences suggest that the effect of endophyte fermentation broth is affected by its concentration. Endophyte fermentation broths have promotive effects on E. nutans seed performance, with associated host variations in the effects of these three endophyte strains.