Bioregulators and poinsettia plant quality

Abstract

Paclobutrazol at 0, 12.5, 25 and 37.5 mg/L and uniconazole at 0, 5, 10 and 15 mg/L were applied both as a foliar spray and as a soil drench to 'Eckespoint Freedom Red' and 'Gross Supjibi Red' poinsettia plants. In both poinsettia cultivars plant size was effectively reduced by paclobutrazol and uniconazole as soil drenches at all concentrations. Applying paclobutrazol (12.5 mg/L) or uniconazole (5 mg/L) as a soil drench reduced poinsettia plant size for a longer period of time than applying either as foliar spray. Growth regulators applied as a soil drench also reduced the bract diameter of both cultivars. The use of growth regulators such as paclobutrazol and uniconazole on poinsettia production can improve plant quality (size) in Puerto Rico.