The Influence of Cobalt and Sugars upon the Elongation of Etiolated Pea Stem Segments

Abstract

Although the fresh weights of sub-apical segments from etiolated pea stems were consistently increased by sucrose added to test solutions containing indole-3-acetic acid (IAA), the elongation of such segments was either only slightly promoted or slightly inhibited by the sugar. Cobaltous salts, when added to IAA solutions, slightly promoted elongation. When sugar and cobalt were added together to the IAA solution, great increases of elongation occurred. The evidence reveals a distinction between the roles of water uptake and cell wall increase in the enlargement of plant cells. It is suggested that sucrose primarily causes increases of cell volume and that cobalt promotes the ability of the cell walls to increase in surface area.