A New Laboratory Method Used for Investigating the Uptake, Translocation and Metabolism of Bark Banded Morphactin by Trees

Abstract

AbstractCut twigs of Monterey pine(Pinus radiata D.Don) were banded with a 14C labelled morphactin formulation and the lower half of the twig placed in a Scholander type pressure bomb. Water was pumped through the twig from a reservoir inside the bomb and exudate collected from the protruding end of the twig. Using this method it was possible to determine that the slowest step in the translocation of morphactin was the passage across the outer layer of bark. Subsequent passage through the twig was not affected by girdling the bark suggesting that morphactin was translocated upwards via the xylem. The 14C compound in the exudate from live twigs differed from morphactin and was tentatively identified as the carboxylic acid derivative of the morphactin ester.The cut twig system facilitated studies on the uptake, metabolism and translocation of morphactin and should prove useful for studying the uptake and fate of other chemicals considered for bark application to trees.