The Effect of Metabolic Inhibitors on Herbicide Movement in Plants

Abstract

Pretreatment of bean (Phaseolus vulgarisL.) petiole sections with one of several metabolic inhibitors greatly stimulated the movement of 3-amino-2,5-dichlorobenzoic acid (amiben) and (2,4-dichlorophenoxy)acetic acid (2,4-D). However, the movement of 3-amino-s-triazole (amitrole), 3-(3,4-dichlorophenyl)-1-methylurea (linuron), and isopropylm-chlorocarbanilate (chlorpropham) was stimulated only slightly or not at all. The basipetal movement of indole-3-acetic acid (IAA) was inhibited by concentrations of 2-sec-butyl-4,6-dinitrophenol (dinoseb) which stimulated respiration (5 × 10−7M to 5 × 10−8M). Acropetal movement was stimulated by dinoseb concentrations greater than 10−5M. Translocation of root-applied amiben and 2,4-D to the stems and leaves of whole plants of bean, squash (Curcurbita pepoL.), and cucumber (Cucumis sativusL.) was stimulated by dinoseb root applications only at concentrations which were highly injurious to the plants. Amiben, 2,4-D, and their metabolites were extracted from dinosebtreated and untreated tissues. The stem exudate from cucumber plants fed amiben and 2,4-D via the roots contained primarily the parent compounds, which indicates that the parent compounds are the primary components translocated through the xylem.

Movement of Several Herbicides Through Excised Plant Tissue

“…When the present data are compared with the mathematical models of Leopold and Hall (12), fixation of 2,4-D by the tissue is indicated. This agrees with results of other studies for 2,4-D translocation in whole plants which show that 2,4-D translocation following root ab sorption is strongly inhibited in some species due to bind ing in root tissue (7,19). However, the apparent conjuga tion and resistance to movement is less for 2,4-D than for amiben (19).…”

“…Therefore, the use of excised petiole section appears to give comparable translocation data to that obtained with whole plants. Little metabolite formation was detected in these tissues by the extraction, separation, and assay methods discussed in another paper by the authors (19). This probably ac counts for the good movement through the tissue, the estimated velocity being 2 mm/hr.…”

Root Absorption and Translocation of Picloram by Oats and Soybeans

“…Another possibility is that the inhibitors stimulated translocation. Several metabolic inhibitors stimulate the movement of herbicides that tend to be bound in transporting tissue (15).…”

Translocation and Complex Formation of Picloram and 2,4‐D in Wheat Seedlings

“…Activity is given in per cent of applied activity. free form of the herbicide is that translocated, one would speculate that any compound which would successfully prevent the metabolic binding of the herbicide could result in increased translocation (Taylor and Warren 1970). However, no stimulation of translocation as a result of cycloheximide pretreatment was observed in spite of the fact that the level of free 2,4-D was substantially increased in the leaves' of these plants (Table 5).…”