Effect of Growth Regulators on the Vegetative Growth of Boronia megastigma ‘Lutea’

Abstract

A survey experiment was carried out to examine the effect of five growth regulators on the vegetative growth of Boronia megastigma. Promalin, daminozide, and chlormequat chloride were shown to have potential for modifying plant growth in the development of a commercial pot plant. Promalin restricted plant height and promoted lateral branch formation; concentrations of 0.5 and 1.0 g·liter–1 restricted height by ≈40% while branch number doubled. Daminozide significantly restricted plant height at concentrations of 5 and 10 g·liter–1. Plants that received a single application of daminozide also showed an increase in branch number. Dikegulac-sodium completely inhibited vegetative growth even at the lowest concentration used (2.5 g·liter–1) while chlormequat chloride, applied as a foliar spray (3 and 6 g·liter–1), restricted both height growth and plant dry weight. Chlormequat chloride and paclobutrazol, applied as root drenches, were ineffective. Chemical names used: butanedioic acid mono(2,2-dimethylhydrazide)(daminozide); N-(phenyImethyl)-1H-purine-6-amine and GA4+7 (Promalin); Na 2,3:4,6-bis-O-(1-methylethylidene)-α-l-xylo-2-hexulofuranosonic acid (dikegulac-sodium); 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat chloride); (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl) pentan-3-ol (paclobutrazol).