Some Properties of a Plant Growth Inhibitor Present in Xylem Sap of Woody Species

Abstract

An ether-soluble, non-toxic inhibitor of plant growth was shown to be present in varying amounts in xylem sap from shoots of various woody species. Some chromatographic properties of the inhibitor are described. The inhibitor reduced growth of wheat coleoptile sections and lettuce hypocotyls, and inhibited germination of lett,uce and cress seeds. The inhibitor did not interact competitively with either auxin in the wheat coleoptile elongation test or with gibberellic acid in the lettuce hypocotyl test. Gibberellic acid did not overcome the inhibitory effect on seed germination. The inhibition of coleoptile section growth was reversed on transfer from inhibitor solution to sucrose solution.