STUDIES ON ABSCISSION: THE INHIBITING EFFECT OF AUXIN

摘要: THE FIRST INDICATION that abscission of leaves is controlled by auxin was given the work Laibach (1933). He showed pollinia orchids, applied to distal cut end a petiole, inhibited petiole. Orchid were known contain auxin, and few years later La Rue (1936) reported an experiment showing synthetic in form indoleacetic acid (IAA) also very effective delaying abscission, if it dark or shade. The first thorough investigation as whether factor which typically nature petiolar Myers (1940a). Using Coleus his experimental miaterial, he those normally stayed longest on plant gave greatest amount diffusible auxin; removing leaf blade greatly accelerated abscission; presence IAA debladed petiole well did blade. experiments cited above give picture speed with any abscises directly coming down from That is, so far concerned, each seems act physiological entity. be described below confirm extend these earlier experiments, while second paper this series (Rossetter Jacobs, 1953) show we must discard being too simple view "with respect entity." METHODS. A clonal stock blumei Benth. grown greenhouse. variety same used Jacobs (1952), Rossetter (1953), Bullwinkel (1953). Supplementary lighting during winter months obtain faster growth. plants trained two-branched excising main stem allowing only two axillary branches develop. All other removed. terminology referring parts shoot (1952) shown diagrammatically fig. 1. "spiral" pattern deblading used: one member pair apical bud excised, petioles arranged spiral (see 1 1953). intact listed control; treated naphthaleneacetic (NAA) at per cent concentrations lanolin; 8