DCPTA Suppresses Growth and Flowering of Amaryllis

Abstract

DCPTA is a synthetically produced tertiary amine bioregulator with potential for increasing crop productivity at high light intensities. DCPTA reduces the number of days from planting to maturity in various potted ornamental crops, including `Fortune' daffodil (Narcissus L.), `Sonora' tulip (Tulipa L.), and `Jan Bos' hyacinth (Hyacinthus orientalis L.). Our objective was to examine how light intensity and DCPTA application influence growth and flowering of amaryllis (Hippeastrum hybridum Hort.). Flowering size bulbs of a micropropagated amaryllis clone were treated with 30 μm or no DCPTA and grown in full sun or 63% shade for 1 year. Number of scapes produced, flowers per scape, change in bulb fresh weight, number of bulblets produced, and bulblet weight were recorded and analyzed. There were no significant differences in days to first flowering or in number of flowers produced per scape among the treatments. DCPTA application at the recommended rate significantly reduced number of emergent inflorescences and the bulb biomass increase of hybrid amaryllis. Additionally, the interaction between light level and DCPTA appeared weak for amaryllis, and was only slightly significant relative to bulblet production. Chemical name used: 2-(3,4-dichlorophenoxy)triethylamine (DCPTA).