|dc.description.abstract||Plants of gorse (Ulex europaeus L.) were grown from cuttings in a glasshouse, and studies were made on metabolism, absorption and translocation of picloram-l-¹⁴C or 2,4,5-T-l-¹⁴C applied to a spine or to a branch of a cutting. Experiments were carried out under constant conditions in a growth cabinet.
Both picloram-l-¹⁴C and 2,4,5-T-l-¹⁴C were rather stable in gorse tissues, although there might be metabolites in little amounts, which could not be identified by chromatography techniques in the experiments. The decarboxylation of the herbicides by gorse was not significant.
Picloram did not significantly increase the ebsorption of 2,4,5-T by single spines incubated in solution, and 2,4,5-T did not affect the absorption of picloram. Quantities of the herbicide in tissues might depend on concentration, amount of the applied herbicide and length of exposure to the solution.
In detached branches, the absorption of picloram and 2,4,5-T by a spine was low. In a whole plant system, the herbicides were translocated towards regions of high metabolic activity such as apical meristems, floral organs, nodules and root apices. Picloram was more mobile than 2,4,5-T. picloram tended to accumulate in floral organs and nodules while 2,4,5-T remained in the main stem of the cutting. In a root system, the herbicides accumulated in root apices rather than in fully differentiated root tissues. Because ring girdling, involving the removal of a ring of bark, did not prevent the translocation of 2,4, 5-T in a detached branch, the herbicide may be translocated in xylem was well as in phloem. The radial movement of 2,4,5-T between xylem and phloem was demonstrated in gorse stems.
Picloram was shown to leak from a root system to the surrounding nutrient solution. An addition of picloram did not significantly alter the distribution of 2,4,5-T, and 2,4,5-T had no effects on the translocation of picloram.||en