Chrysanthemum can do with less "end of the day" far red light

Added on 06 October 2022

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Chrysanthemum can do with less end of the day far red light

In recent years, interest in LED lighting among chrysanthemum growers has increased considerably. When choosing the LED lighting system, it is important to make a good choice with regard to the efficiency of the lamps and the right spectrum for the crop. When growing under full-LED, growers fear that the branches might remain too short in winter. Therefore, we are looking for possibilities to control the elongation of chrysanthemums with light spectrum.

Research conducted by the business unit Greenhouse Horticulture of Wageningen University & Research in 2021 showed that stem length under full-LED can be controlled very well by "end of day" far-red light of 20 ?mol/m˛/s far-red light for 30 minutes. In addition to longer flower stems, cultivation was accelerated with a few days. The question now is whether the same effect can be achieved with a lower intensity or a shorter period of "end of the day" far-red light. Other questions addressed in this study are whether the "end of the day" far-red light is needed throughout the entire cultivation, and whether extra far-red light during the day at the start of the crop improves root growth of the cuttings.

To answer these questions, the cultivation of four chrysanthemum varieties (Magnum, Baltica, Chic and Pina colada) under 200 ?mol/m˛/s full LED in the Innovation and Demonstration Centre LED lighting (IDC LED) started in May 2022. "End of day" far-red light duration was reduced from 30 to 20 and 10 minutes (20 mol/m˛/s) and the intensity of the far-red light was reduced to 10 and 5 mol/m˛/s (for 30 minutes). In addition, in the base spectrum, the percentages of green and far-red light were varied and cultivation was carried out at a lower light intensity (100 ?mol/m˛/s) in order to reduce the energy consumption of an illuminated chrysanthemum cultivation.