| Abstract: | ABSTRACT: Sediments were investigated from two Florida lakes that have not been infested with the submersed, perennial, noxious plant Hydrilla verticillata. Aqueous extracts of the peat-like sediments from these lakes were shown to inhibit the growth of Hydrilla verticillata in laboratory systems. The extracts have substantial concentrations of organic carbon and iron. The apparent molecular weight of the inhibitory fraction is between 2,000 and 10,000, based upon ultrafiltration studies. Hydrilla growth was about 35 percent relative to control for a partially purified fraction at a level of 0.4 ppm organic carbon. Growth was measured as change in biomass (wet and dry) over a one-week period. The inhibitory material was highly fluorescent, dark brown, and inhibitory activity was lost after passage over an anion-exchange column (Cellex-D). |
