Effect of infection by the endophytic fungus Acremonium lolii on growth and nitrogen uptake by perennial ryegrass (Lolium perenne) in flowing solution culture

Clonal tillers of a genotype of perennial ryegrass (Lolium perenne), either with or without the endophytic fungus Acremonium lolii, were grown under natural light in flowing nutrient solutions with mineral N maintained automatically at concentrations of 3 or 30μm NH₄NO₃ for 28 days. Uptake of N was monitored daily and dry matter production was assessed by sequential harvesting. The presence of endophyte had no significant effect on shoot or root biomass production at either N level, but shoot: root ratios were significantly increased by endophyte infection at both N levels at some harvests. All plants absorbed NH₄⁺ preferentially to NO₃^- and the ratio was not affected by endophyte infection. Also, infection did not affect total N content of plants, which was significantly more in plants at the higher N level than at the lower level. It is concluded that endophyte infection had only minor effects on growth and N economy of the plant, under the conditions imposed in this experiment.