Effects of Paclobutrazol on Growth and Flowering of Bouvardia humboldtii

Abstract Plant height of potted Bouvardia humboldtii Hort. was controlled effectively by foliar or drench applications of paclobutrazol. Three foliar applications of 250 mg·liter −1 paclobutrazol or a drench of 2 mg/100-mm-diameter pot reduced plant height by≈30% and increased the total number of flowers per plant by ≈35%. Overall, paclobutrazol significantly reduced total plant dry weight, and sprays were more inhibitory than drenches. Paclobutrazol altered the shoot : root ratio in favor of the shoot. Foliar sprays of daminozide (5000 mg·liter −1 ) or chlormequat (2000 mg·liter −1 ) were ineffective in controlling growth or flowering. It is concluded that paclobutrazol application may be a useful technique in the commercial production of Bouvardia as a flowering pot plant. Chemical name used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1 H -1,2,4-triazole-l-ethanol [paclobutrazol (ICI-PP333)].