End-of-day treatments as a way of controlling growth in ornamental pot plants

• With the introduction of light emitting diode (LED) technology for greenhouse lighting, the possibility to apply narrow band light becomes available to the grower. With narrow band light, it is possible to target the different photoreceptors of the plant, and thus control plant growth and development. Applying a brief period of narrowband light at the end of the photoperiod (end-of-day lighting) has been suggested as a way to control growth with a low total input of electric energy. Controlling stem elongation is an important part of greenhouse horticulture, especially for ornamental crops but also for vegetable transplants. Chemical plant growth regulators are efficient and widely used for this purpose, but questioned from an environmental point of view and not compatible with organic practices. In a series of experiments, end-of-day treatments with different wavebands were applied to poinsettia plants in order to evaluate the concept and to establish the most suitable wavelength. Red (660 nm), green (525 nm), and white (continuous spectrum) LED lights were evaluated. End-ofday light was applied for one hour after the main photoperiod, at an intensity of 10 µmol m-2 s-1. A treatment without end-of-day light was used as the control treatment. The results displayed significant differences among treatments.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Trädgårdsvetenskap/hortikultur (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Horticulture (hsv//eng)

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