Herbicide Uptake and Regrowth Ability of Tall Fescue and Orchardgrass in S-Metolachlor-Contaminated Leachates from Sand Pot Experiment

The ability of tall fescue (Festuca arundinacea L.) and orchardgrass (Dactylisglomerata L.), to remediate leachates polluted with S-metolachlor (SMR) has been assessed in static hydroponic cultures. Different SMR concentrations (0.25, 1.00, and 2.00 mg L−1) were applied in the growth media to test the capacity of the two grasses to tolerate and uptake this herbicide, and to regrowth after mowing. S-metolachlor did not severely affect the dry weight aerial biomass of D. glomerata and F. arundinacea, which were reduced by 5% and 10%, respectively, when compared to the untreated control, regardless ofthe SMR concentrations in the leachate. The regrowth ability of aerial biomass after mowing was reduced at the different SMR concentrations, according to a dose–response model. The SMR concentrations, which reduced the regrowth ability of F. arundinacea and D. glomerata of 10% and 30%, were found to be EC10 (Effective Concentration) of 0.21 and 0.38 mg L−1 and EC30 of 0.45 and 0.74 mg L−1, respectively. These values could be assumed as the SMR concentrations that were well tolerated by both the species, without compromising their aerial biomass regrowth. Finally, tall fescue was found to be more effective and faster than orchardgrass in decreasing the SMR in the leachate and, therefore, this species should be preferred to be used in the vegetative buffer strips (VBS).