Diphenamid Metabolism in Pepper and an Ozone Effect. I. Absorption, Translocation, and the Extent of Metabolism

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Abstract
Nutrient-solution-grown pepper (Capsicum frutescens L. ‘Early Calwonder’) absorbed 62% of the diphenamid (N,N-dimethyl-2-2-diphenylacetamide) supplied via the roots for 48 h, and 74% in 150 h. Extensive translocation accompanied absorption, and 70 ± 3% of the absorbed 14C was present in shoots of plants harvested after 24- to 150-h treatments. Diphenamid was metabolized rapidly to chloroform-soluble and water-soluble compounds, and to unextracted residues. Chloroform-soluble compounds persisted for 150 h and accounted for more than 50% of the 14C in leaves. Water-soluble compounds other than N-hydroxymethyl-β-D-glycosides accounted for 25% of the water-soluble metabolites in leaves of nonfumigated plants. Ozone fumigation did not affect diphenamid absorption or translocation significantly. In leaves, ozone-enhanced accumulation of water-soluble metabolites more polar than N-hydroxymethyl-N-methyl-2,2-diphenylacetamide-β-D-glucoside (MDAG) and unextracted residues was observed. Ozone fumigation reduced the accumulation of these 14C-fractions in roots.