Response of poinsettia to drench application of growth regulators

Author: Kristina Batelja Lodeta ^*, Smiljana Goreta Ban, Slavko Perica, Gvozden Dumičić and Lovre Bućan

Received 7 August 2009, accepted 30 December 2009.

Abstract

The effect of drench applications of combinations of chlormequat chloride (2-chloroethyl-N,N,N-trimethyl-ammonium chloride) and daminozide (N-dimethyl amino succinamic acid) on the growth and pigment concentration of the poinsettias cv. Christmas Feelings was studied. Combinations of chlormequat chloride (500, 1500 or 3000 mg·L^-1) and daminozide (2500 and 5000 mg·L^-1) were applied three times. Root drench application of a combination of chlormequat chloride and daminozide did not cause visible phytotoxic symptoms on plants. No interaction between chlormequat chloride and daminozide was found for height and diameter of the plants, or area and dry weight of the leaves and bracts. Daminozide after the second application caused shorter plants compared to the control, while after the third application both chlormequat chloride at 1500 and 3000 mg·L^-1 and daminozide at 5000 mg·L^-1 caused around 20% shorter plants. Leaves and bract area were affected only by chlormequat chloride, and compared to the control, they increased with application of 500 mg·L^-1 chlormequat chloride and decreased at higher application rates. An interaction between tested compounds after the third application was found for the length of laterals, dry weight of the main stem and laterals and pigment concentration. The length of laterals was the most reduced for the combination of the highest rates of both compounds, whereas the dry weight of the main stem and laterals increased at the lowest concentrations. Chlorophyll a, chlorophyll b and carotenoid content in leaves was enhanced compared to the control in combinations where daminozide was applied at 2500 mg·L^-1, whereas in bracts, the chlorophyll and carotenoid levels increased for all chlormequat chloride and daminozide combinations.

Key words: Chlormequat chloride, daminozide, Euphorbia pulcherrima, growth retardation, pigments..