Epichloe fungal endophyte colonisation and seed quality in developing grass florets - effect of different fertiliser applications

Perennial ryegrass is an important pasture, forage and turf plant, and in New Zealand, it is commonly and intentionally inoculated with selected beneficial endophyte strains. These endophytes provide enhanced traits to their host grasses with AR37, a market leading strain, conferring a broad spectrum of insect deterrence coupled with excellent animal performance. The effect of different nitrogen forms, with and without potassium, on a range of seed quality parameters, and presence of AR37, was determined. TSW and seed germination did not respond to nitrogen application. However, a combination of nitrogen and potassium reduced TSW and seed germination and increased empty seed percentage. There was no influence of spikelet position on any of the seed quality parameters measured. However, within a spikelet, there was an effect of floret position on TSW, empty seed and endophyte presence. The effect varied depending on whether nitrogen was applied as nitrate or ammonium.