Effects of fungal endophytes on the growth of perennial ryegrass under drought condition

The present study explored the effects of fungal endophytes on host growth with endophyte-infected (E+), endophyte-free (E-) and mixture of E+ and E-(M) populations of L. perenne under two different growth environmental conditions including greenhouse and field. In green house, four different water treatments including 15%(FWC15), 30%(FWC30), 45%(FWC45) and 60%(FWC60) of field water content (FWC) were simulated in pots. The results showed that the plant height and tiller numbers, growth rates of plant height and tiller, blade width and length, aboveground water content and aboveground biomass of E+, E- and M gradually increased with the increase of soil moisture content in greenhouse which reached maximum under FWC45 treatment. However, the growth indices of plants under FWC60 moisture condition were less than those of plants under FWC45 treatment which suggested that FWC60 treatment inhibited plants growth. All these results suggested that FWC45 was optimal condition for perennial ryegrass. The tiller numbers, growth rate of plant height and tiller, blade width, aboveground water content of E+ populations were significantly higher (P<0.05) than those of E- and M populations and the blade length of E + populations were significantly higher (P<0.05) than that of E- populations under each moisture condition in pot experiment. There were no significant difference between E+ and M population for aboveground biomass with FWC60 treatment, while E+ populations were significantly higher (P<0.05) than that of M populations (P<0.05) under other treatments. With FWC15, FWC30 and FWC45 treatment, aboveground biomass of E+ population were significantly higher (P<0.05) than those of E- and M populations although there were no significant difference between E- and M populations, however, aboveground biomass of E+ and M population were significantly higher (P<0.05) than that of E- populations. Under natural field conditions, the plant height and tiller numbers, growth rates of plant height and tiller, blade width and aboveground biomass of E+ populations were significantly higher (P<0.05) than those of E- and M populations, while the blade length and aboveground water content had no significant difference with M population. The growth indices of E- were significantly (P<0.05) less than those of E+ population. These results suggested that the fungal endophytes could promote the growth and enhance the drought resistance of L. perenne in the greenhouse and field conditions.