| Abstract: | Abstract. This study examined the influence of the fungal endophyte Neotyphodium lolii on the competitive interactions between its perennial, cool season host, Lolium perenne (perennial ryegrass), and a warm season, annual grass, Digitaria sanguinalis (large crabgrass), in densely planted stands (>1000 plant.m?2) in the glasshouse. Endophyte infection had little or no effect on L. perenne tiller production, above‐ or below‐ground biomass or root: shoot ratio in monoculture. However, endophyte infection significantly reduced L. perenne tiller production and above‐ground biomass in mixtures with D. sanguinalis. Conversely, D. sanguinalis had significantly higher above‐ground biomass and yielded more seed (g) when competing with endophyte infected L. perenne. An apparent trade‐off between allocation of resources to reproductive vs root tissues was observed in D. sanguinalis– root: shoot ratio was significantly lower when competing with endophyte infected L. perenne. Results indicate negative ecological consequences for harbouring the fungal endophyte when competing with the fast growing annual grass in newly established stands. These findings underscore the existence of a physiological cost of harbouring the fungal endophyte which is often overlooked. |
