La présence de l'acide abscissique dans les tiges de hêtre et sa relation éventuelle avec l'activité cambiale

Summary Endogenous abscisic acid was quantified by gas—liquid chromatography in apical and basal parts of upper beech branches, cut in november and january from trees 6 m in heigth. The amount of ABA per g. dry weight was higher in the apical part than in the basal part of branches, in the cortex than in the wood. ABA—GE level also seemed to predominate in the cortex of apical stem part. The transport of 3H-ABA, laterally applied on the stem of beech, was essentially acropetal. Microautoradiographs indicated that label was located in the phloem and in the cambial zone. Endogenous ABA level in the upper cm of the stem, quantified by gas—liquid chromatography and radioimmunoassay, varied irregularly and did not appear to be correlated with seasonnal variations of cambial activity.