Effects of endophyte infection on seed germination, seedling growth and osmotic stress resistance of perennial ryegrass (Lolium perenne L.)

The seeds were all stored for 18 months but in two different ways: either in a growth cainet at 20deg C, or in a refrigerator at 4deg C. There has been evidence that storing grass seed at room temperature for more than one and a half years can lead to an inability of endophyte transmission from seed to seedlings. The effect on endophyte infection on leaf extension seemed to vary with PEG stress levels. The rate of leaf extension was greater in EF seedlings than in EI seedlings under the control treatment. This difference seemed to disappear under 10% PEG stress, and under 20% PEG stress, EI seedlings became superior in leaf elongation. There was no significant positive effect of endophyte infection on the total number of tillers per pot. EF seedlings tended to have more tillers, more leaves per tiller and greater dry weight of individual tillers by the end of the test than did EI seedlings, but this difference was not statistically significant. There was an interactive effect between endophyte infection and PEG stress on the total length of root system: under control and 10% PEG stress, the total length of EF seedlings was greater than EI ones; have any positive effect upon aboveground or underground biomass of seedlings, but appeared to increase the proportion of assimilative tissue in the infected plant.