Abstract
The uptake and distribution of bensulfuron methyl (DPX F5384), the active ingredient in “Londax” herbicide, was examined in rice roots and shoots. When roots were directly exposed (short-term uptake) to a solution containing 14C-bensulfuron methyl, considerable uptake of 14C material was observed. In contrast, when rice was grown in soil in a simulated paddy environment (long-term uptake), shoots tended to accumulate more 14C material than roots.
Extraction of 14C material from roots and shoots of plants exposed to bensulfuron methyl (in solution) for 24 hours revealed rapid metabolism of the compound by shoots but not by roots. Shoots converted 72% of the accumulated 14C material to a polar metabolite, whereas in roots, 76% of the extracted 14C was associated with parent material.
These data indicate that rice roots can potentially accumulate bensulfuron methyl to a significant extent when directly exposed to the compound. However, due to soil binding kinetics in the paddy ecosystem, relatively little bensulfuron methyl would be available for root uptake. This was substantiated by the smaller degree of 14C accumulation in rice roots compared with shoots, when plants were grown in soil.
