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This article in AJ

  1. Vol. 86 No. 2, p. 243-246
    Received: May 18, 1993

    * Corresponding author(s):
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Allelopathic Characteristics of Three Cool-Season Grass Species in the Forage Ecosystem

  1. A. E. Smith  and
  2. L. D. Martin
  1. U niv. of Georgia College of Agric., Georgia Stn., Griffin, GA 30223-1797
    I nst. of Agric., Curtin Univ., Northam, WA, Australia.



Allelopathy, the direct or indirect effect of one plant on another through the production of chemical compounds that escape into the environment, occurs widely in natural plant communities and is postulated to be one mechanism by which weeds interfere with crop growth. The purpose of this research was to determine the potential allelopathic influence of selected cool-season grass species on species interseeded into the pasture ecosystem. Aqueous extracts of tall fescue (Festuca arundinacea Schreb.), Italian ryegrass (Lolium multiflorum Lam.), and little barley [Critesion pusillum (Nutt.) A. Löve; syn. Hordeum pusillum Nutt.] leaf and stem tissue harvested at the mature stage of plant development reduced seed germination and seedling growth of alfalfa (Medicago sativa L.) and Italian ryegrass. It was estimated that 2.8 and 2.5 g L−1 aqueous extracts of mature tall fescue stem tissue, resulted in a 50% reduction in alfalfa seed germination and seedling growth, respectively. For the extracts from Italian ryegrass and little barley, it was estimated that tissue concentrations of near 5.0 g L−1 resulted in a 50% reduction in seed germination and seedling growth for the two bioassay species. Leaf and stem tissue concentrations of the three grasses >7.0 g L−1, resulted in complete inhibition of alfalfa seedling growth. The potential concentration for foliage tissue in soil solution of the pasture ecosystem for tall fescue, Italian ryegrass, and little barley would be 28, 23, and 9 g dry wt. L−1, respectively. Therefore, the allelopathic characteristics of these species could be of economic importance in the pasture ecosystem when overseeding the pasture with annual ryegrass or alfalfa.

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