Potencial alelopático de macrófitas aquáticas de um estuário cego

aquatic macrophytes represent one of the most productive communities and through metabolic activity are capable of producing great interference in the environment. allelopathic interactions are apparently increased under biotic and abiotic stress and may exist in estuaries due to competition, salinity variation and other factors. the aim of this study was to evaluate the allelopathic properties of leaf extracts of 25 aquatic macrophyte species from a blind estuary. we tested leaf extract effects in four concentrations on the germination of lettuce. we ranked and compared the donor species according to the dose-response over the variety of treatments through unique values of allelopathic indexes. eleven of 25 species decreased the germination percentage, all of them decreased the speed of germination and increased the germination informational entropy of the target species seeds in at least one of the tested concentrations. crinum americanum l., sagittaria montevidensis cham. & schl. and ipomoea cairica (l.) sweet presented the highest allelopathic index values. in general, the lowest germination percentages concurred with the lowest germination speed and highest germination informational entropies of lettuce seeds, showing an assemblage of alterations occurring simultaneously with the increase of extract concentrations.