Submitted to: American Forage and Grassland Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2004
Publication Date: 6/1/2004
Citation: Belesky, D.P., Burner, D.M., Ruckle, J.M. 2004. Herbage mass and allocation of a tall fescue cultivar as a function of native or non-toxic endophyte. American Forage and Grassland Conference Proceedings. v. 13 p. 388-392. Interpretive Summary: Some fungi live entirely within a host plant and can have detrimental effects on the physiology and behavior of grazing livestock that consume the plant-fungus association. The association is very specific, but new technologies have allowed introduction of certain fungal strains into productive plant hosts that do not have detrimental effects on grazing livestock. Fungal infection often benefits productivity and persistence of the host plant, but the influence of novel associations on host productivity and persistence is unclear. A controlled environment experiment was conducted to determine how tall fescue allocated resources among plant parts and how plants grew when clipped repeatedly. The host plants had a native or novel endophyte, or were non-infected. The plants hosting the novel endophyte were the smallest among the host- fungus associations; however, these plants allocated more photosynthate to shoots than roots compared to native fungus or non-infected plants. Total leaf mass and rate of tiller production of very young, establishing plants were not influenced by host-endophyte association. Differences in total mass and relative allocation of mass among plant parts could influence the success of juvenile plants in the establishment phase, and competitive ability with other plants in a pasture over the long term as the host-association ages.
Technical Abstract: Novel non-toxic endophytes inserted into host plant cultivars can elicit specific metabolic responses that minimize the harmful effects of endophyte-infected grasses on grazing livestock. However, very little is known about the mechanisms of competitiveness of non-toxic host-endophyte associations. Endophytes influence growth and tillering in grass hosts and could influence how plants partition resources and compete for space in a sward. A controlled environment experiment was conducted to determine dry matter allocation patterns among plant structures, and leaf and tiller appearance rates of repeatedly defoliated tall fescue (Festuca arundinacea Schreb.) plants (Jesup, and Jesup/Max-QTM), differing in endophyte [native (J+); non-infected (J-); non-toxic endophyte, AR542 (Max-Q)]. Whole plant mass of Max-Q was least among the associations; however, Max-Q allocated more photosynthate to shoots than roots compared to J+ or J-. Cumulative leaf mass and rate of tiller production of establishing plants was not influenced by host-endophyte association. Differences in total mass and relative photosynthate allocation could influence competitive fitness of juvenile plants.