Evidence for inhibitory allelopathic interactions involving phenolic acidsin field soils: Concepts vs. an experimental model

The accepted criteria for identifying allelopathic interactions in the fiel d that have been proposed in the literature offer heuristic function, but t o date have failed as a framework for research and diagnostics. If the pres ent criteria are to be modified to make them useful empirically, their shor tcomings must be identified. For this review, data from the Literature and from defined model systems consisting of plants, soil, and/or microbes are used to evaluate the applicability of the accepted criteria to defined syst ems in which plants are responding to known allelochemicals. Based on this evaluation, modified criteria are proposed. In many respects, however, the modified criteria are as difficult to satisfy in the field as those propose d previously. The new criteria have value as a research framework because t hey clearly suggest that a shift in research focus to the soil environment, specifically the barrier of the rhizosphere through which allelochemicals must pass, is essential if the role of allelopathic interactions in the fie ld is to be established.