DOES AUXIN STIMULATE THE ELONGATION OF INTACT PLANT STEMS?

Abstract

Contradiction exists in the literature as to the effect of exogenous auxin on the growth of intact plants, and the assumed lack of such an effect has been used as evidence that auxin does not function in regulating growth through changes in concentration. Indole‐3‐acetic acid (IAA), applied in lanolin to the third internode of intact etiolated Pisum sativum L. cv. Alaska stems, rapidly and markedly stimulated elongation, to an extent similar to that observed in excised segments. This was a short‐term effect and did not alter the final stem size attained after 24 or 50 h. Decapitated plants responded more slowly to IAA application but, again, the final size attained was similar to that of the untreated controls. The results show that changes in auxin amounts cannot be ruled out in discussions of growth regulation. Copyright © 1985, Wiley Blackwell. All rights reserved