Metabolism of terbacil in orange seedlings.

Orange seedlings were cultured in aqueous solutions of 3-tert-butyl-5-chloro-6-methyluracil (terbacil and terbacil-2-14C). Radioactivity was distributed throughout the plant with the largest amount in the roots and the smallest amount in the leaves. Terbacil was metabolized to form 3-tert-butyl-5-chloro-6-hydroxymethyl uracil, which was conjugated to form a beta-glucoside as the conjugate was hydrolyzed by beta-glucosidase. Identification of the metabolite was made by infrared and mass spectrometry after isolation and purification by column and thin layer chromatography. An additional unidentified water-soluble material was accumulated in the plant. 5-chloro-uracil was not detected as a metabolite of terbacil.