Endophytic fungi in meadow fescue and other forage grasses
Abstract: Many cool-season forage grasses associate with an endophytic fungus of the genus Epichloë. In Sweden one of the most important forage grasses is meadow fescue (Festuca pratensis Huds.), which is known to associate with Epichloë uncinata, previously named Neotyphodium uncinatum. Since the 1970's extensive research has been done on grass/endophyte symbioses, with focus on tall fescue (Festuca arundinacea Schreb.) and perennial ryegrass (Lolium perenne L.) and their fungal symbionts, due to their production of toxic alkaloids. Given the importance of meadow fescue in Sweden and the Nordic countries the aim of this thesis was to study the symbiosis between meadow fescue and E. uncinata and to evaluate effects that E. uncinata may have on meadow fescue grown in Sweden. The studies focused on differences in seed germination, winter survival and plant growth between endophyte-infected and uninfected plants, as well as effects of nitrogen fertilization on loline alkaloid production. Knowledge about optimal seed storage conditions and uniform germination behavior can generate economic profit in seed production and for farmers. Meadow fescue seed that started to germinate early had higher frequency of viable endophytes than seed starting germination later, and heavy seed had higher germination rate and germination frequency than lighter seed. During seed storage for 3.4 years in different packaging materials and environments, seed stored in paper bags in freezer (-20 °C) had the highest seed germination and endophyte viability. In a field cultivation of meadow fescue the effect of endophyte infection on meadow fescue during two growing seasons was studied. Plants were given either a nitrogen fertilization that is normal for the area or half that amount of nitrogen. Plants fertilized with normal amount of nitrogen produced more tillers per plant. Endophyte-infected plants produced more tillers per plant than uninfected plants, but there was no difference in total biomass production or winter survival between endophyte-infected and uninfected plants. Lolines were produced by infected plants, but the production did not differ between nitrogen fertilization levels. Lolines are known to be deterrent to some insects but are not toxic to larger mammals.
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