Phytoremediation of quinclorac and tebuthiuron-polluted soil by green manure plants

Quinclorac and tebuthiuron are residual herbicides that may remain in the soil longer than for the cropping season. The objective of this research was to evaluate the use of green manure plants to remediate soils treated with quinclorac and tebuthiuron. Soils were separately treated with(14)C-quinclorac and(14)C-tebuthiuron at 266.4 and 132 g ha(-1), respectively. After 21 days, four green manure plants, namelyCrotalaria spectabilis,Canavalia ensiformis,Stizolobium aterrimum, andLupinus albus, were separately sown in the treated soils. Overall, all four species absorbed more(14)C-tebuthiuron [C. ensiformes(22.49%),S. aterrimum(16.71%),L. albus(15%), andC. spectabilis(4.48%)] than(14)C-quinclorac [C. ensiformis(13.44%),L. albus(10.02%),S. aterrimum(6.2%), andC. spectabilis(1.75%)]. Quinclorac translocation in all four plants was greater in young leaves compared to old leaves, cotyledons, or roots, and(14)C-tebuthiuron translocation in all four plant species was greater in old leaves and cotyledons compared to young leaves or roots. Regardless of the differences in translocation between the two herbicides, the four green manure plants are capable to remediate soils that have been treated with quinclorac and tebuthiuron. However,C. ensiformisis more efficient for the remediation of tebuthiuron-treated soil compared to the other plants.