By – Céline De Baere, Tomato Product Specialist.
More and more growers are testing led-lights in tomatoes, mainly to try and reduce energy costs. Depending on the lighting system used, the saving can be from 35% to 50% and maybe even more. LED-lights in tomato are being tested in North West Europe for two seasons, a good time to make an initial summary.
It is a well-known fact that plants have better assimilation under specific wavelengths. Tomato plants need more red and blue light then other colors. And since with better assimilation higher yield can be achieved, since leaves use red light more efficiently for photosynthesis, in theory up to 20% more yield is possible. However, the first two years of trials only averaged 5% yield increase, since a theory is good for a single leaf, and in a whole crop the result is different. On top of that, when a whole plant is involved the transportation of assimilates to their growing points is also an important factor.
LEDs emit almost no heat. This is why they can be placed inside the canopy thus delivering the light exactly where it is needed, much closer to the plant. And we also don’t “steal” any sunlight, like normal artificial lights (SON-T lights) do. Mine due, we might compensate for the loss of heating radiation when heat is needed for development of the crop.
Two main points limit the use of led-lights in tomatoes – efficiency and costs. Efficiency of the LED-lamps needs to be improved and cost must be compatible with conventional lighting system. A combination of energy saving with extra yield will make the LED a winning technology in greenhouse tomato production.
More information is still needed before we can say that LED is an established technology. Questions such as how to combine LED and non LED lights, the consequences of uncouple heat radiation, PAR-light and far red light as well as coping with lower plant temperature must be further investigated.