Studies on the Absorption, Translocation, and Action of CMU

Publisher Website
Google Scholar
Abstract
CMU, 3-(p-chlorophenyl)-l, 1-dimethylurea, was shown to be less volatile than the isopropyl or butyl esters of 2,4- dichlorophenoxyacetic acid (2,4-D) and less selective. No cellular modifications were induced except for the collapse of the softer cells and tissues. The action of this chemical was slow, no effect being obtained for several days after treatment. Entry took place readily through leaves, stems, or roots. Entry was much more rapid through the ventral leaf surface than through the dorsal. Movement of CMU in the leaf was most rapid between the veins and appeared to be blocked by the larger veins. It did not translocate readily from the leaf to the stem. Velvetbean plants were killed by an immersion of one-half of the root system in 200 ppm. CMU solution for 15 min., demonstrating that entry and translocation were very rapid in the roots. Movement of the CMU was primarily upward and the experimental evidence indicated that the path was through the xylem and the transpiration stream. Conditions favoring reduced transpiration resulted in a reduced CMU injury. Excision of the xylem prevented passage of the CMU, but excision or burning of the phloem did not prevent the movement upward. Excised roots were grown successfully for 3 months in sterile nutrient culture containing CMU in amounts'' sufficient to kill intact plants in 2 weeks indicating that the toxic action of CMU is primarily on the aerial portion of the plant.