"More photosynthesis thanks to diffuse coating"
Cymbidiums aren’t exactly sun worshippers. During the summer, Eric van Paasen typically closes the screen at 450 Watt/m². "That usually means I close it at 10 am, and open it again at 6 pm," he says. "But I can’t close it completely because of ventilation. It usually remains open a quarter, so there’s still some sunlight creeping in. Conversely, the other three-quarters are a bit too dark."
Van Paasen cultivates 1.5 hectares of mini cymbidiums near the Dutch town of 's Gravenzande. The greenhouse’s diamond glass lets in extra light, including some UV-B. In autumn, winter and spring that extra light is attractive. In summer however, extra light equals extra heat.
There’s no shortage of screens on the lot. "With the outdoor screen you can remove the heat radiation on the glass, while still ventilating adequately. We can thus achieve a greenhouse temperature that is 5 to 6 °C below the outside temperature, say from 31 °C to 25 °C," says Van Paasen.
Letting in more light
It was the positive experiences with the outer screen, that stimulated Van Paasen to seek a better solution for the other half as well. "From colleagues I had heard about ReduFuse IR, which peeked my interest immediately. We’ve been working with it for about a month now, and the experience shows that we can easily allow more light in without the crop showing discolouration. Id’s say the biggest gain is that we don’t have to close the screen before noon, opening it again at about 5 pm. This way the plants get a few more hours of light.”
Increased photosynthesis
That extra light of course leads to increased photosynthesis, and thus to more reserves in the plant. For that reason, the grower expects to see a positive effect on both stem numbers and stem length. The control options on vegetative and generative growth have increased as well. "It just looks good," he says. Van Paasen will likely leave the coating on until the end of September, depending on the weather forecast.
More information:
Barry Zuidgeest
Mardenkro
06 2951 1880
[email protected]
