Biomass and tiller growth responses to competition between Ky31 and MaxQ Festuca arundinacea cultivars and response of Ky31 to exogenously applied liquid preparation of Neotyphodium coenophialum under glasshouse conditions

Tall fescue ( Festuca arundinacea ) forms a mutualistic symbiosis with the fungal endophyte Neotyphodium coenophialum which produces ergot alkaloids toxic to grazing animals. One approach to reduce pathological effects has been to introduce an exotic endophyte that does not produce toxic compounds yet still confers host‐plant benefits. We measured biomass accumulation and competition between two tall fescue cultivars with different endophytes grown in close proximity and tested if compounds from endophytes can diffuse from one plant to another. Ky31 (tall fescue with natural endophyte) and MaxQ (tall fescue with introduced exotic endophyte) were grown separately and together in a pot experiment under greenhouse conditions. The cultivars had comparable biomass production in monoculture, but when grown in mixed‐culture MaxQ had a significantly lower tiller number (2.92 ± 0.15 tillers/plant) and size (0.048 g ± 0.003) than Ky31 (4.06 ± 0.16 tillers/plant) (0.072 ± 0.002 g). Aqueous endophyte preparations were made and applied topically to E+ and E‐ Ky31. E‐ plants receiving doses of this preparation produced significantly more tillers (3 ± 0.18 tillers/plant) and larger tillers (0.074 ± 0.006 g) than untreated control plants (2.2 ± 0.13 tillers/plant) (0.0428 ± 0.0072 g). These observations suggested that a diffusible compound might induce a growth benefit conferred by the tall fescue endophyte.