A E. Smith, University of Georgia

Publication Date

1989

Description

Allelopathy, the direct or indirect effect of one plant on another through the production of chemical compounds that escape into the environment (Rice, 1974) occurs widely in natu­ral plant communities (Gressel and Holm, 1964), and is pos­tulated to be one mechanism by which weeds interfere with crop growth (Gressel and Holm, 1964; Bell and Koeppe, 1962; Muller, 1966). Probably the most significant consequence of allelopathy is the alteration of population densities that affect vegetation patterns in plant communities. The actual and potential roles of allelopathy in agriculture have been exten­sively reviewed (Putman and Duke, 1978; Rice, 1974; Rice, 1979). Generally, allelopathy has been found to be of greater importance when vegetation residues are left on the soil surface compared with annual incorporation of residue into the soil (Guenzi et ai., 1967). This would indicate that weed inter­ference with crop production, by allelopathy, would be most prominent in rangeland, pastures, and minimum tillage farm­ing. The objectives of this research were to : 1) identify the potential allelopathic influence of certain pasture weeds and 2) determine specific allelopathic characteristics of bitter sneezeweed [Helenium amarum (Raf.) H. Rock].

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Allelopathic Influence of Certain Pasture Weeds

Allelopathy, the direct or indirect effect of one plant on another through the production of chemical compounds that escape into the environment (Rice, 1974) occurs widely in natu­ral plant communities (Gressel and Holm, 1964), and is pos­tulated to be one mechanism by which weeds interfere with crop growth (Gressel and Holm, 1964; Bell and Koeppe, 1962; Muller, 1966). Probably the most significant consequence of allelopathy is the alteration of population densities that affect vegetation patterns in plant communities. The actual and potential roles of allelopathy in agriculture have been exten­sively reviewed (Putman and Duke, 1978; Rice, 1974; Rice, 1979). Generally, allelopathy has been found to be of greater importance when vegetation residues are left on the soil surface compared with annual incorporation of residue into the soil (Guenzi et ai., 1967). This would indicate that weed inter­ference with crop production, by allelopathy, would be most prominent in rangeland, pastures, and minimum tillage farm­ing. The objectives of this research were to : 1) identify the potential allelopathic influence of certain pasture weeds and 2) determine specific allelopathic characteristics of bitter sneezeweed [Helenium amarum (Raf.) H. Rock].