Endophytic fungi affect growth of perennial ryegrass

Clones of Lolium perenne L. 'Grasslands Nui' perennial ryegrass, either infected with or free from Acremonium loliae Latch, Christensen & Samuels, and clones of 'Grasslands Ruanui' perennial ryegrass, either infected with or free from a Gliocladium-like endophyte, were grown at 20°C for 8 weeks in a controlled-environment room. Nui plants infected with A. loliae yielded 38% more total dry matter than uninfected plants. Infected plants showed significant increases in total leaf area, tiller numbers, and growth of leaves, pseudo stems, and roots, but the shoot: root ratio was unaffected. Infection of Ruanui with the Gliocladium-like sp. had no significant effect on yield even though total leaf area was reduced by 19%. The benefits in yield and protection from damage by Argentine stem weevil from A. loliae-infected ryegrasses are discussed in relation to the known risk of ill-health in animals grazing infected pastures.