Cucumber Bioassay and HPLC Analysis to Detect Diuron Residues in Remineralized Soils Following Canavalia ensiformis Cultivation as a Phytoremediator

The aim of this study was to evaluate the role of rock powder in the phytoremediation of Inceptisol (sandy loam) and Oxisol (clay) contaminated with diuron. Canavalia ensiformis plants were grown in pots containing 7.5 kg of both soils, with doses of 0, 4, and 8 t ha−1 of rock powder. Diuron was applied in doses ranging from 875 to 3500 g of a.i. ha−1. The injury level was assessed at 42 days after emergence (DAE), and the morphological characteristics were assessed at 120 DAE. After phytoremediation, the soil was analyzed using High Performance Liquid Chromatography (HPLC) and by bioassay with cucumber (Cucumis sativus) to detect diuron. In Oxisol, no injury was observed, and the rock powder (4 t ha−1) benefited the growth of C. ensiformis regardless of the dose of diuron. In Inceptisol, the greatest reduction in growth occurred with 3500 g a.i. ha−1 of diuron and 8 t ha−1 of rock powder. Diuron was detected after 120 days in Inceptisol with 2625 g a.i. ha−1 without rock powder and 3500 g a.i. ha−1 with and without rock powder. The cucumber bioindicator in Inceptisol showed an increase in the level of injury as the dose of diuron increased. The rock powder favored the growth of C. ensiformis and was able to phytoremediate high concentrations of diuron, which supports the safe use of this herbicide for weed control, minimizing environmental impacts.