Abstract
Numerous successful methods of the cutting propagation of woody plants performed in the last ten years are based on the high pressure Fog-system. Not much is known about the role of the auxin applied to the cuttings before being put into the substrate. The most important issues are the uptake and distribution of the added auxin in the cuttings and its metabolism. Three experiments have been carried out to resolve the questions. The auxin IAA naturally present in plants was used in these experiments. The cuttings of both fruit rootstocks, the easy-to-root 'Gisela 4' and the difficult-to-root 'M9/4-80' took up ca. 30 % of the added IAA. The distribution of IAA differed between the two rootstocks. In the cuttings of 'Gisela 4' a greater amount of IAA remained, taken up for a longer time in the lower parts of the cuttings (root emergence zone) than in the cuttings of 'M9/4-80'. In the cuttings of 'Gisela 4' the auxin was present during the first six days mostly in the form of free acid. These results could explain the better rooting of the cherry cuttings. The auxin taken up was translocated to the upper parts of the water saturated cuttings with the same speed as in normally treated cuttings (or even more quickly). The mass-flow is not the cause for this translocation. There must be other mechanisms in the plants which coordinate the auxin movement.

Key words:Prunus, Malus, green cuttings, auxin uptake, IAA.