Eindhoven, the Netherlands – Taste matters when growing tomatoes, and our research shows that tomatoes grown under LED grow lights have great taste. Over the years, we have noticed that consumers, and therefore retailers and growers as well, find flavor increasingly important. The choice of cultivar plays an essential role, of course, but so do the growth conditions which influence the taste. Therefore, plant specialist Charlotte Pijnenburg has done research into the effect of LED lighting on the flavor of the fruits. She investigated two hypotheses: first, are tomatoes grown under LED as tasteful as those grown under HPS, and second, can LED light help to increase the taste?
Finding the right spectrum
There are several spectra which could have a beneficial effect on the flavor of tomatoes. Blue light, for example, is known to have an interesting effect. In several crops it is shown that increased levels of blue light positively influence taste and smell. Another interesting light spectrum is far-red, of which it is also known that it can improve the taste of the fruits. However, far-red can cause undesired effects, like increased stem-length. We also know that blue light can do the opposite and decrease the stem-length. By combining blue and far-red we might get the best of both worlds: increased taste without additional stretching.
For this first trial, we looked at four different spectra:
1. The control spectrum: our standard red, blue, light blue spectrum, which is optimized for tomatoes.
2. The control spectrum plus additional far-red.
3. A high blue spectrum, where part of the red light is replaced by blue.
4. A high blue plus far-red spectrum, where we have both the extra blue and the extra far red added.
As for the trial set-up, we looked at two cultivars: Piccolo and De Ruiter cultivar 564. These are both cherry tomatoes, they are both comfortable in the same climate, of a similar size, and they are also both known for their good taste. Yet genetically they differ greatly.
The trial was performed at the WUR (Wageningen University) greenhouse in Bleiswijk, using a full LED lighting solution. We used a PAR-intensity of 210 µmol/m2/s, consisting of 135 µmol/m2/s toplighting and 75 µmol/m2/s interlighting. The far-red was additional, so on top of the PAR intensity, and was only added from the interlighting. The trial area was about 110m2.