The capacity of switchgrass (Panicum virgatum) to degrade atrazine in a phytoremediation setting

Atrazine is a widely used herbicide in agriculture. Non-point source contamination of groundwater and drinking water may pose a significant threat to humans, wildlife, and the environment. Phytoremediation may provide a cost-effective strategy for reducing non-point source contamination of atrazine from agricultural runoff. Previous studies have shown that the rhizosphere of the native prairie grass, switchgrass (Panicum virgatum) is capable of enhancing the degradation of atrazine in soils. Biodegradation also may occur within the plant biomass; however, the extent to which this occurs has not been studied. We hypothesize that switchgrass has the capacity to degrade atrazine in vivo, in addition to the microbial biotransformation that occurs in its rhizosphere. The goals of this study were to characterize the ability of switchgrass to take up atrazine from soils, quantify the amount of biodegradation occurring in the plant, and quantify the amount of degradation occurring in the rhizosphere. Switchgrass seedlings were transplanted into autoclaved and non-autoclaved sand containing 10 µg/g atrazine in sand. Treatments were sacrificed on days 0, 3, and 7. Sand and plant tissue extracts were analyzed by gas chromatography to determine the concentration of atrazine and metabolites in sand and plant tissues. Results demonstrated that leaf biomass is capable of detoxifying atrazine, because metabolites were present in leaf material and not in the sand or root.