Does allelopathy offer real promise for practical weed management and for explaining rhizosphere interactions involving higher plants?

This paper selectively reviews developments in the study of allelopathy, pr incipally from a chemical standpoint. Particular attention is given to rece ntly discovered aspects of signalling within the rhizosphere rather than to direct physiological effects caused by broadly active allelopathic agents with only a brief review of the role of bulk generation of weakly biocidal material. Many of the chemicals responsible for allelopathic effects have b een identified and the biosynthesis and modes of action of a number are inc luded. The paper also highlights instances where signalling aspects of alle lopathy may be exploited for practical weed control purposes, and how the s tudy of allelopathic components of the rhizosphere metabolome might be stud ied more directly by means of plant genomics.