Studies on the stimulation of abscission by malformin on cuttings of Phaseolus aureus Roxb

Abstract

White light irradiance required for complete and slight inhibition of malformin-induced abscission by cuttings of Phaseolus aureus was 13.5×103 and 0.1×103 ergs/cm2. sec, respectively. Longer photoperiods and higher irradiances were required to inhibit abscission by malformin-treated cuttings than by controls. Malformin stimulated dark abscission more rapidly, and at lower concentrations, than Ethrel or abscisic acid. The ability of light to inhibit malformin-induced abscission diminished rapidly after 36 hr in the dark. Malformin accelerated chlorophyll and fresh and dry weight loss of leaves in the dark. The loss in fresh and dry weight, and perhaps chlorophyll, were inhibited by light. Hydroxyproline had little effect, but sucrose, hadacidin, kinetin and indoleacetic acid delayed malformin-induced abscission. Although puromycin, an inhibitor of protein synthesis, stimulated abscission on controls, it inhibited malformin-induced abscission.