The use of plants for the phytoremediation of contaminated soils requires that the concentrations of the pollutant lay within the limits of tolerance of the plant in order to ensure the efficacy of the treatment. The vegetative propagation and growth of the aquatic herbaceous plant Echinochloa polystachya were studied by planting parts of stems in 2 L of várzea soils previously contaminated by crude oil from Urucu, in 7 different dosages of oil ranging from 0 to 0.46 L m-2. The experiment took place in a green house and the plants were monitored during a 70 days period. Increasing the oil concentration lead to the decrease of the above-ground biomass, the ratio alive aerial biomass/total aerial biomass, leaf length and number of leaves. The interaction between dosage and time of exposition contributed for a reduction in the number and length of leaves, height of insertion of the first leaf, and increase of the number of unhealthy leaves. The use of E. polystachya for phytoremediation may be limited to soils with lower concentrations of crude oil from Urucu.
Central Amazon; Floodplains; Aquatic macrophytes; Phytoremediation
