Zonal Geranium Growth and Flowering Responses to Six Growth Regulators

Two experiments were conducted to compare the efficacy of uniconazole (10-ppm spray and drench), paclobutrazol (15-ppm spray and drench), triapenthenol (132-ppm spray and drench), chlormequat (1500-ppm spray only), ethephon (500-ppm spray only), and chlormequat + daminozide (2500 + 1500 ppm spray only) combination for controlling stem elongation of zonal (cutting) geraniums [Pelargonium hortorum (L.H. Bailey)]. Additionally, the effect of these materials on days to anthesis, inflorescence number, and phytotoxicity was evaluated. Spray applications provided effective height control and did not affect days to anthesis or inflorescence number. Drench applications severely restricted growth and reduced inflorescence number, but did not delay flowering. None of the treatments was phytotoxic. Chemical names used: β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-l,2,4-triazole-1-ethanol (paclobutrazol); 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat); α-cyclopropyl-α-(4-meth-oxyphenyl)-5-pyrimidinemethanol (ancymidol); (2-chloroethyl) phosphoric acid (ethephon); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide); β-(cyclohexylmethylene)-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol (triapenthenol); (E)- 1-(p-chlorophenyl)-4,4-diemethyl 1-2(1,2,4-triazol-2-yl)-1-penten-3-o1 (uniconazole).