Absorption, Translocation, and Metabolism of Bentazon in Sunflower (Helianthus annum)

Addition of a surfactant (alkylaryl polyglycol ether) increased the rate and quantity of14C-bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] absorbed by leaves of 3-week-old hydroponically grown sunflower (Helianthus annuusL.). Autoradiographs and radioassays of plant parts indicated that the surfactant enhanced acropetal movement of bentazon in sunflower, whereas bentazon applied alone remained in the treated leaves. Basipetal movement of14C-bentazon was insignificant in sunflower. High-pressure liquid chromatography showed that 3 days after treatment 40% of the absorbed14C-bentazon was metabolized to a methanol-soluble metabolite. Thinlayer chromatography substantiated the occurrence of a14C-bentazon metabolite 3 days after treatment.