Naar een duurzame chrysantenteelt: effect van LED lichtspectra en -intensiteit : Deelrapport I van het project 'LED licht met de zon mee'

Achieving the desired stem length is important in the winter cultivation of chrysanthemums under LED lighting. Earlier research showed that stem length under full-LED can be controlled by “end of day” lighting with 20 μmol/m²/s far-red light for 30 minutes. The question is whether the same effect can be achieved with a lower intensity or a shorter period of “end of the day” far-red light. Measurements on four chrysanthemum varieties grown under 200 mol/m²/sfull LED showed that the effect of 20 or 10 minutes of “end of the day” far red light was comparable to 30 minutes of 20 μmol/m²/s far red light. Reducing the intensity of the “end of the day” far red to 10 or 5 μmol/m2/s also had asimilar effect. To obtain this effect, lighting with “end of the day” far red light only during the first weeks of cultivation is not sufficient. The “end of the day” far red light has a greater effect on elongation or time to harvest than the lightspectrum during the day, where the proportion of green light was varied between 0 and 15% at the expense of red light. These results show that it is quite possible to grow chrysanthemums under full LED, and that there are sufficientpossibilities with light colors to control the crop in such a way that a desired stem quality can be achieved.