Effects Of Endophyte On Growth And Drought Resistance Of Perennial Ryegrass

The present study explored the effects of fungal endophytes on host growth and physiological characteristics using endophyte-infected(E+), endophyte-free(E-) and mixture of E + and E –(M) populations of Lolium perenne under two different growth environmental conditions including greenhouse and field. The main results are summarized as follows:1、 The results showed that the soil moisture had strong effects on plant growth. 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 45% field water capacity(FWC). However, the growth indices of plants under 60% moisture condition were less that those of plants under 45% FWC which suggested that treatment with 15%, 30% and 60% FWC inhibiting plants growth. All these results suggeted that 45% moisture were optimal contions for perennial ryegrass.2、 Endophyte also had strong impacts on host growth. 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. There was no significant difference between E+ and M population for aboveground biomass under 60% moisture treatment while there were significant difference(P<0.05) under other treatments. These results suggested endophyte was very important for host-perennial ryegrass growth under stressful conditions.3、 Endophyte also improved host growth under natural condition. Under natural field conditions, the plant height and tiller numbers, growth rates of plant height and tiller, blade width and aboveground biomass of E+ population 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 suggests that the fungal endophytes could promote the growth and enhance the drought resistance of L perenne in the greenhouse and field conditions.4、 Endophyte increased host drought or waterlogger resistance by improving host enzyme activities and accumulated more chemicals. Endophyte significantly increased the chlorophyll content, soluble sugar content, proline acid content, superoxide dismutase(SOD) activity and catalase(CAT) activity of ryegrass(P<0.05), but the Malondialdehyde(MDA) content and Peroxidase(POD) activity were reduced when the water content was 15% FWC(drought) and 60% FWC(waterlogger) of the soil saturated water content under greenhouse different water treatment; These three populations have no significant difference in physiological parameters at 45% FWC which showed that the endophyte increased the resistance of the host by improving the protection of enzyme activity under stress conditions.5、 Endophyte improve host growth by affecting host physiology. Under natural field conditions, the changes of chlorophyll content, soluble sugar content, proline content, SOD activity and CAT activities in ryegrass showed that E +> M> E-, MDA content and POD activity showed that E-> M> E +. In conclusion, endophyte also can promote the growth of hosts by changing the internal physiological mechanisms under natural growth conditions.