GROWTH AND WATER STATUS IN MEADOW FESCUE IS AFFECTED BY NEOTYPHODIUM AND PHIALOPHORA SPECIES ENDOPHYTES

Growth and water status in meadow fescue (Festuca elatior L.; syn. F. pratensis Huds.) is affected by Neotyphodium and Phialophora endophyte s. Meadow fescue is often infected with Neotyphodium uncinatum (Gams, Petrini & Schmidt) Glenn, Bacon, Price & Hanlin or cosymbiotically wit h this and a Phialophora-like endophyte. In a growth chamber experimen t, we determined the influence of these endophytes on selected growth attributes and plant water status of one genotype of meadow fescue. Si ngle plants of clone M1 free of endophytes (E-) or infected with N. un cinatum (N), Phialophora-like endophyte (P), or both endophytes (NP) w ere adequately irrigated (control plants) or subjected to a gradually established soil water deficit for 26 d (stressed plants). Afterwards, stressed plants were rewatered and allowed to regrow for 4 wk. Cumula tive herbage dry matter (DM) yield was greater in P plants hy 7.5% com pared with N plants, generally, Control P plants produced more root DM than E-and NP plants. Root DM in N plants was significantly greater d uring recovery from drought, compared with P and NP plants (36%). Till er number of NP plants was the lowest among endophyte treatments in th e predrought period. In response to water stress, P plants produced mo re tillers than E-plants (24%), but average tiller weight of P plants was lower than in E-plants (14%). During imposed water stress, stomata l conductance (g(s)) and leaf water potential (psi(L)) decreased in al l plant-endophyte associations to a similar extent. At severe soil wat er deficit, however, N plants had significantly lower g, and psi(L) th an the other plant-endophyte associations. Control plants benefited fr om the symbiosis with endophytes by increasing: root growth (both endo phytes) and shoot growth (Phialophora-like endophyte). Plants infected with N. uncinatum were potentially able to adjust to soil water deple tion earlier, suggesting a greater potential for adaptation to drought .