PLANT STRESS AND ALLELOPATHY

Secondary metabolites in plants are known to contribute to the defense mechanism against herbivores and disease organisms. Concentrations of these compounds are often enhanced by biotic and abiotic stress and this reallocation of photosynthate is believed to be a part of the evolutionary adaptation. Similar rationale may be given to the possible enhancement of allelopathy under environmental stress. The increase of allelopathic phenolic and terpenoid compounds under environmental, stresses has been well documented, and our work on purple nutsedge (Cyperus rotundus L.) showed that water stress enhanced phytotoxic secondary metabolites in both plant tissue and in the rhizosphere. While crucial questions remain unanswered, research on stress and allelopathy would provide valuable information in understanding both natural and agricultural ecosystems.