Metabolism of Sandoz 6706 in Soybean and Sicklepod

The metabolism of Sandoz 6706 [4-chloro-5-(dimethylamino)-2-α,α,α-trifluoro-m-tolyl-3(2H)-pyridazinone] in soybean [Glycine max (L.) Merr. ‘Kent’] and in sicklepod (Cassia obtusifolia L.) was examined at 1, 2, 4, and 8 days after herbicide application to explain the relative susceptibility of soybean and sicklepod to the herbicide. The 14C-labeled Sandoz 6706 was applied via the plant roots in a liquid culture medium. The primary pathway of metabolism in both plant species involved N-demethylation to norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone and the desmethyl Sandoz 9774 [5-amino-4-chloro-2-(α,α,α-trifluoro-m-tolyl-3(2H)-pyridazinone]. Soybean was more efficient in the N-demethylation of the herbicide to less toxic metabolites than was sicklepod. A second transformation pathway which resulted in the formation of polar products was present in the roots of both species.