Translocation of 14C assimilates in Rumex obtusifolius and Polygonum bistorta

1. Rumex obtusifolius and Polygonum bistorta were labeled with 14CO2 at 4 and 3 growing periods respectively and the distribution of 14C-activity was measured. A partly quantitative connection between translocation of 14C-assimilates and 14C-phenoxy herbizides rises the possibility to find the optimum application period for herbizides. 2. In Rumex obtusifolius before shooting the assimilates were translocated at an appreciable amount into the roots. While shooting and flowering however, the assimilates were predominantly found in the shoot. Independently in the first three growing periods young roots are the prefered target of 14C-assimilates. At seed maturity the roots are hardly provided with assimilates. 3. In Polygonum bistorta the assimilates especially at flowering are translocated to the shoot. After flowering a turn back takes place so that the roots and the end points of the rhizomes are prefered targets of 14C. 4. In order to get maximum effect applying phenoxy herbizides Rumex obtusifolius should be treated before flowering, Polygonum bistorta after flowering. (orig.)