For plants to grow well in greenhouses, they need the right temperature and also the right light. Light in the deep red spectrum plays an important role in plant growth because the absorption of chlorophyll in this red range is very high. OSRAM SYLVANIA’s Golden DRAGON Plus and OSLON SSL now provide this deep red light with particularly high efficiency with typical power of 330 mW at an operating current of 400 mA. Their chips are based on OSRAM’s thin-film technology, and with a life of 100,000 hours they offer maintenance-free operation for many years.
Golden DRAGON Plus has a wide beam angle of 170° and can be used with good effect in reflector systems for illuminating large areas under cultivation. OSLON SSL has a smaller footprint and a narrow beam angle of 80° which means they can be arranged close to one another. They can also be equipped with external optics. Their unique characteristics make them ideal for special applications such as “multi-layer cultivation” in which salad plants are grown on stacked levels. In this arrangement it is important for the lighting to be both compact and uniform.
A recent pilot project, completed in cooperation with Fionia Lighting A/S and the OSRAM distribution partner Arrow in Denmark, confirmed the energy-saving potential of LEDs in horticultural applications. As part of the project, Fiona Lighting A/S developed a luminaire system specifically for greenhouses which was equipped with a total of approximately 50,000 Golden DRAGON Plus LEDs. Over a cultivated area of several thousand square meters it was possible to reduce power consumption by 40%.
“Flowers cultivated under LED lighting developed just as quickly as the control specimens under conventional lighting. Also the flowers cultivated under the LED lights had more buds which attracted higher sales prices”, said Thomas Rubaek of Fionia Lighting A/S with justified pride. “At the same time we were able to reduce the use of chemicals such as growth regulators.”
The colors red and blue are particularly important for plant growth. The emission curve of the new red LED is a good match for the spectral sensitivity of chlorophyll. Depending on the type of plant and the growth phase, the ratio of red and blue has to be individually adjusted between 10 and 30%. Dr. Christoph Gärditz from the SSL Business Development department at OSRAM Opto Semiconductors explains: “If the emission curve of the light source is mapped against the spectral sensitivity curve of the plant (according to DIN 5031-10) the system luminous efficacy with LEDs is 60% higher than with the high-pressure sodium lamps currently used. The combination of deep red and blue LEDs offers impressive energy savings in this project as well.”
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