Influence reciproque de quelques substances de croissance dans la culture de tissu de topinambour (Helianthus tuberosus L. var. ‘Violet’). III. Comportement du tissu apres transfert sur milieu depourvu d’auxine

Jerusalem artichoke tissues were cultured for 1-4 days on media containing different labelled auxins (IAA-1-14C and 2,4-D-14C) before being transferred to a medium without growth substances. The development of tissues and the fate of the incorporated substances were studied and compared with those of tissues maintained on the same medium throughout. Explants had absorbed enough IAA in 2 or 3 days to develop like others kept on the original medium. In the case of 2,4-D development of the explants was even better when transferred after 3 days to a medium without auxin. When IAA was used incorporated radioactivity was found in lAAsp and an unidentified substance A; growth is determined by the ratio of substance A to lAAsp. With 2,4-D label is retrieved as 2,4-D itself as well as another unidentified substance D: here also growth is determined by the ratio of 2,4-D to substance D.