Replacing PAR light with far-red light:

“Far-red light boosts tomato yield”

The use of artificial lighting in greenhouse horticulture has significantly increased in recent years, both in acreage and intensity, resulting in a strong rise in power consumption. One of the advantages of LED lighting compared to SON-T lighting is the higher energy-efficiency of the LEDs. Another advantage is the fact that LEDs can emit light with specific colors. In the Carbon-LED project, Wageningen University & Research, Philips, Bayer CropScience, INRA and Startlife are working together on the design of energy-efficient production systems for greenhouse horticulture, using LED lighting.

In the 2016-2017 light season, different tomato varieties were cultivated using LED lighting with and without extra far-red light. All varieties benefited from the additional far-red light, with higher yields as a result. The beneficial effect differed per variety. In another test, far-red light was added to SON-T lighting, which also increased the yield.

More far-red light
Using additional far-red light for cultivation uses more power as well, so during the 2017-2018 light season researchers are investigating to what extent the far-red light can replace some of the PAR light. The test is being conducted at Wageningen University & Research, business unit Greenhouse Horticulture in Bleiswijk. Tomatoes of the varieties 'Progression' and 'Extension' were planted on October 20, 2017. The lighting consisted of 210 μmol/m2/s red/blue LED light and 35 μmol/m2/s far-red light in combination with 175 μmol/m2/s red/blue LED light. The amount of illumination in both setups is comparable, as is the power consumption. Researchers want to find out what the partial replacement of PAR light with far-red light means for photosynthesis, assimilate distribution, growth and yield.

In the winter months, about 80% of the PAR light that the crop receives comes from lamps. In the area with far-red light, that caused the total PAR light sum to decrease by 15%. Nevertheless, the tomato yield is comparable in both treatments. It is too early to draw conclusions, because there is still plenty of illumination being done. The trial runs until the end of April, at which point the data will be analyzed and used for recommendations for an effective lighting strategy for tomatoes.

The Carbon LED project is funded by the European Union (EIT via Climate KIC) and the Dutch Ministry of Agriculture, Nature and Food Quality.

For more information:
Kas Als Energiebron
www.kasalsenergiebron.nl

Publication date: Mon 16 Apr 2018