Auxin-gibberellin relationships in their effects on hypocotyl elongation of light-grown cucumber seedlings III. Gibberellin specificity in its enhancing effect on IAA-induced elongation

Pretreatment effects of different gibberellins, helminthosporic acid, cyclic AMP and Kinetin on subsequent IAA-induced elongation were tested in cucumber hypocotyl sections. Gibberellin A7 was more active than GA3, while gibberellin A3 was almost inactive. Both helminthosporic acid and cyclic AMP mimicked GA3-action, though the degree of their activity was less. Kinetin pretreatment resulted in marked inhibition of IAA-induced elongation. The pretreatment effect of GA3 was also reflected in a greater responce of the sections to synthetic auxins.