Growth, Morphological, and Chemical Component Responses of Tall Fescue to Acremonium coenophialum

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Abstract
A symbiotic relationship exists between the endophytic fungus, Acremonium coenophlalum Morgan‐Jones and Gains and tall fescue (Festuca arundinacea Schreb.). The response of the host planto the endophyte has been studied by comparing infected or noninfected populations in the field or by an individual plant genotype in the greenhouse. The lack of a more thorough investigation of tall fescue genotypes with and without their endophytes suggests that known responses of tall fescue plants to endophyte infection are limited to the restricted conditions by which they were tested. The objectives of this study were to determine variability in responses of tall fescue genotypes to endophyte infection for select growth characteristics, plant morphology, and chemical components. Five genotypes of tall fescue were grown in both endophyte‐infected (EI) and noninfected (NI) forms in the greenhouse under different clipping treatments. Tiller and dry matter production, crown depth, and total nonstructural carbohydrates (TNC) were measured. In addition, leaf area per plant (LAP), specific leaf weight (SLW), and ergovaline duction were measured on two diverse plant genotypes. Forage yield, tiller number, and TNC varied for EI and NI treatments among plant genotypes. Dry matter production per tiller was greater and crown depth was approximately 1‐cm lower in EI plants than NI plants. Leaf area was greater in EI plants but SLW was higher in EI Genotype 7 (3.94 vs. 3.65 mg cm−2) and lower in El Genotype 17 (4.25 vs. 4.91 mg cm‐2) compared to their NI forms. Ergovaline production was constant regardless of leaf area in Genotype 7, but increased linearly with leaf area in Genotype 17. We conclude that endophytes increased phenotypic variation in this study and thus may increase the ability of mixed EI and NI populations to adapt to diverse environments.