Science - February 24, 2005

PRI to test red greenhouse light

While greenhouses will not start flashing like the LED cycle lamps do, researchers at Plant Research International hope that greenhouse energy consumption can be reduced by using pulsating lights for assimilation lighting.

Tests will start at the end of April under the Dutch Horticultural Product Board. The idea behind using LEDs (Light Emitting Diodes) in greenhouses is that plants do not absorb light continuously. If chlorophyll absorbs energy in short bursts, it should in principle be possible to supply light in similar short bursts.

Plant Research International will investigate whether photosynthesis and growth of indoor plants is the same when pulsating light is used instead of continuous light. KEMA, an independent research and consultancy bureau for electrical energy will supply the lighting.

Plant Research International will test an LED system with mainly red LEDs that have a high pulse rate. Red light requires the least amount of energy to produce and is better absorbed by leaves than other colours. This contrasts with the sodium lamps currently used in greenhouses, which emit mainly yellow and orange light. ‘In addition to improving energy use, we may be able to reduce light pollution,’ explains PRI researcher Dr Tom Dueck. ‘Red light is less visible to humans, and the light pulses quicker than the human eye can see. Total light emissions will decline, but we don’t yet know how people will react to red greenhouse light at night.’ / YdH