Allelopathy in the New Zealand grassland/pasture ecosystem

The research (performed both locally and abroad) on the allelopathic potential of most common New Zealand pasture plants (including important weeds) is reviewed. The bioassay techniques usually used for demonstrating allelopathic influences have several drawbacks, often making the observed inhibitory effect of the donor plant a possible artefact of the method used. Other criteria required for the demonstration of allelopathy in the field have been sparingly satisfied, including the chemical identification of toxins, demonstration of concentration of toxins in the field, and the elimination of other possible factors explaining interference in the field. It is concluded that, to unequivocally prove allelopathy, one must first demonstrate that toxins from one plant are taken up by neighbouring plants and produce an inhibitory response. Studies of interference phenomena (including allelopathy) between plants in pastures might be potentially useful for weed control, or for determining mutual compatibility of different species in pasture mixes.