Abstract
This study was carried out to determine the rates of release of 5 polyphenolic allelochemicals, namely, (+) catechin (CAT), eugeniin (EUG), and ellagic, gallic and pyrogallic acids (EA, GA, PA, respectively), by Myriophyllum spicatum, and their growth inhibition effect on the cyanobacterium Microcystis aeruginosa. The calculated release rates were 0.040 nmol · g-wet-1 · h-1, 0.80 nmol · g-wet-1 · h-1, 1.7 nmol · g-wet-1 · h-1, 0.18 nmol · g-wet-1 · h-1, and 0.17 nmol · g-wet-1 · h-1 for CAT, EA, EUG, GA, and PA, respectively. Continuous addition of the 5 polyphenols to the cyanobacterial medium demonstrated the growth inhibition of M. aeruginosa, and the observed inhibitory effect suggested that the 5 polyphenols account for the allelopathic effect of M. spicatum on M. aeruginosa by 70% at the maximum. In addition, a comparison of the release rates of the 5 polyphenols and DOC from M. spicatum indicated that about 10% of organic carbon released from M. spicatum was accounted for by these polyphenols.
