PHENOLIC-ACID CONTENT OF VEGETATIVE PROPAGULES OF POTAMOGETON SPP ANDHYDRILLA-VERTICILLATA

Plant phenols serve as defenses against attack by microorganisms and h erbivores. Phenolic acid content of propagules of submersed aquatic pl ants were measured for three Potamogeton species and two biotypes of H ydrilla verticillata. Mean phenolic acid content ranged from 6.9 +/- 0 .9 (mean +/- standard error) to 53.1 +/- 7.3 mu M g dw(-1). Turions of monoecious Hydrilla verticillata had the lo west phenolic acid conten t while Potamogeton gramineus winter buds had the highest phenolic aci d content. In general Potamogeton propagules had higher phenol content s than Hydrilla propagules. Within species there was no significant ne gative relationship between propagule nitrogen content (%) and phenoli c acid content, but across species phenolic acid content increased wit h increasing nitrogen content. This information will be useful in asse ssing the susceptibility of aquatic weeds to biological control techni ques.