THE EFFECT OF TEMPERATURE AND LIGHT QUALITY ON STEM ELONGATION OF CHRYSANTHEMUM

It has been generally accepted that the change from night to day temperature has to coincide with daybreak to obtain a reduced stem elongation at negative DIF (low day/high night room temperature). It is necessary to ventilate at sunrise to get a quick drop in temperature.
This resulted in a higher energy consumption at negative DIF.

However, investigation under controlled environmental conditions at the Department of Horticultural Engineering, have proven that the internode length of Dendranthema grandiflora can be significantly reduced when the low temperature regime is started two hours before daybreak.
Irradiation with red light during these hours did not alter this result.

First European Workshop on Thermogenesis and Photomorphogenesis in the Cultivation of Ornamentals

Lars H. Jacobsen, Marius G. Amsen

https://doi.org/10.17660/ActaHortic.1992.305.5