Lichtspectrum als middel voor energiezuinige rozenteelt : praktijkproef bij Van der Arend Roses

During the winter 2014-2015 a research was conducted at a commercial rose nursery to learn more about the influence of a special lamp light spectrum on the production and quality of the rose Avalanche. A “hybrid” lighting system was installed with 103 µmol /m2s PAR from High Pressure Sodium and from Valoya LED lamp G1 in two different intensities: 57 or 103 µmol /m2s PAR. Compared with the conventional installation of the company (191 micromol SON-T), the spectrum of the hybrid installation allowed, depending on the intensity of the added LED, a 7.2% to 9% higher light use efficiency (LUE) by the crop. This offers possibilities for energy saving, but therefore the energy efficiency of the lamps used (Valoya G1) needs to increase to an output of 1.7 µmol PAR per watt electric. Valoya is already working on this improvement. The performed plant measurements (SPAD, bud temperature, photosynthesis, leaf area, etc.) do not contribute to explain this positive effect. More research about the effects of light colour on the rose production is needed. Remaining questions are if other rose varieties react the same to the combined spectrum, if the crop can grow more compact in winter when there is more blue in the spectrum, and if a larger proportion of far-red light could make the flowers even heavier, with a larger flower bud. The research was funded by the program “Greenhouse as Energy Source” (Ministry of Economy and the Horticultural Product Board) and Valoya.