Uptake,translocation, and metabolite partitioning of14C-labeled metribuzin in plant growth-regulated soybean (Glycine max)

Plant growth regulator (PGR) application decreased uptake of 10^–6 M¹⁴C-labeled metribuzin (4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one) into leaf interveinal areas of 21-day-old soybean seedlings. BAS 140 810, (N-allyl-N-2-(2,4,6-trichlorophenoxy)ethyl-piperidinium-bromide), as a seed treatment or 10^–6 M triapenthenol or RSW 0411 (B-(cyclohexalmethylene)-gamma-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol) in nutrient solution slowed interveinal unloading of metribuzin and altered metabolite pools. Stems and roots of PGR-treated plants exhibited significantly greater water-soluble metabolite pools than untreated controls. TLC metabolite identification indicated an increase in metribuzin conjugates. This may contribute to the mode of action involved in the apparent safening mechanism. Furthermore, floating leaf disk studies with metribuzin showed plant growth regulation figured prominently in safening against the cessation of oxygen evolution.