Heteroauxin und polaritaet, morphologische und elektrische, bei Coleus-stecklingen

Transport of 3-indoleacetic acid (IAA) in Coleus cuttings is only towards the base (indicated by root formation). The physical basis of Went's theory (1932) on IAA anion attraction by a positive pool and repulsion by a negative pool, was shown to be incorrect. Yet potential difference (PD) could be responsible for polar transport. PD-measurements showed that with both normal and inverted cuttings the upper end was always more negative than the lower (held) end. As also no apical transport of basally applied IAA took place in inverted cuttings, PD was not the cause of polar transport. But in inverted cuttings with apically applied IAA upward basal transport took place, against the assumption of electrical transport. Before root formation, the PD was equal in normal and inverted cuttings, independent of IAA application. After root formation, however, the cuttings with and without IAA all showed a marked PD.

An electrical field did not influence IAA transport but weak electric currents induced apical root formation in normal cuttings with apically applied IAA, so that IAA is probably retained. 0,01μg IAA only induced root formation, larger doses also cambial activity, formation of callus, tracheal elements and sclerenchyma bundles (otherwise occurring at older age),