Microcuttings of apple rootstock 'Jork 9' were rooted by a 'quick dip' in IAA (IAA= indole acetic acid). For histological studies, sampling was done every 4 hours. A precise description of the main stages is, however, only possible between 20 and 140 hours after the auxin treatment. The three chosen biochemical markers evolved as follows: there were two peaks of total peroxidasic activity (day 2 and 7), the level of free IAA increased during the first day and gradually decreased until day 8, and the specific phenolic compound (tR 26.95)(tR= retention time) peaked twice (day 2 and 5) each time free IAA decreased.