Nitrogen-form and endophyte-infection effects on growth, nitrogen uptake, and alkaloid content of Chewings fescue turfgrass

Chewings fescue (Festuca rubra L. ssp. commutata Gaud) is naturally infected by an endophyte, however, little is known about the biology of this association and the effects on host fitness. A hydroponic study was conducted in the greenhouse to determine if endophyte and/or nitrogen (N) form influenced growth, N accumulation and alkaloid production in 'Jamestown II' Chewings fescue. Endophyte-infected and non-infected grasses were established in solution culture for 5 weeks using a 1/4 strength modified Hoagland solution, and then grown for 15 d in similar solutions containing 50 mg L-1 of N as either NH4-N, NO3-N or a 1:1 mixture of NH4-N and NO3-N. The presence of the endophyte increased total biomass 54% in this grass, but growth was unaffected by N source. Nitrogen uptake was 58% higher in endophytic grasses, but no differences were observed in N use efficiency with respect to non-endophytic grasses. Nitrogen form affected both N uptake and N use efficiency, with significantly higher values for plants growing in nutrient solutions containing NH4-N. Endophytic grasses contained two alkaloids, ergovaline and peramine. Grasses grown with NH4-N had significantly higher ergovaline levels than grasses receiving NO3-N whereas N-form had no effect on peramine. These results suggest that management factors, including N fertilization, might influence the production of specific alkaloids in endophyte-infected grasses and potentially enhance resistance against insect pests.