Summary.Seedlings of Galinsoga parviflora and Polygonum convolvulus were cultured in nutrient solution and soil with C‐1983‐14C. Uptake and translocation of herbicide was followed by measuring radioactivity in roots, stems and leaves as a function of time. The capacity of the two plants to take up C‐1983 from nutrient solution and to translocate it into stems and leaves was found to be strikingly different. The difference in herbicidal effect of C‐1983 on the two species parallels the concentration of radioactivity translocated into leaves. Uptake of C‐1983 from nutrient solution as well as subsequent translocation to top parts by lowering temperature increasing humidity and transfering the plants from light to darkness.In soil cultures, the two plants were found to take up and to translocate smaller quantities of C‐1983 than was to be expected from the calculated soil solution concentration.The mechanisms regulating the rate of uptake C‐1983 from nutrient cultures and soils are discussed. The strong adsorption of C‐1983 in tissues appears to be a decisive factor in controlling movement of the herbicide in plants.Le comportement de la N'‐(4‐chlorophenoxy)‐phenyl‐NN‐dimethyluric (C‐1983) dans les terres et dans les plantes II. Absorption e
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