THE BASIC ACTION OF GIBBERELLIC ACID IN ELONGATION OF ‘METEOR’ PEA STEMS

Abstract

The published evidence on the histological action of gibberellins does not favour the widespread belief that the primary action of gibberellic acid (GA) in stem growth is on cell elongation. Histological evidence from Meteor pea internodes shows that the main effect of GA is to stimulate cell division; and even when applied to internodes which have passed into the vacuolation phase of growth GA often re‐activates cell division. Mitotic activity in the apical meristem of Meteor pea stems is also stimulated by GA. The experimental results suggest that the primary effect of GA on caulescent plants, as on rosette plants, is to increase mitotic activity in apical and sub‐apical meristems; the cell elongation effect of GA may well be a derivative of the increased mitotic activity, possibly through an increased production of auxin in the meristematic region. Copyright © 1966, Wiley Blackwell. All rights reserved