"Filtering out blue light improves stem length"

The colour of light has an impact on the growth and development of the plants. Plants can ‘see’ colours with light-sensitive pigments such as phytochrome, cryptochrome and phototropins. Each of these pigments is sensitive to a certain range of colours. The colour of light causes such a pigment to be switched to a particular setting. It is the starting signal for a whole series of processes that ultimately determine the structure of the plant. Therefore by controlling light, you can control the plant’s shape.

Longer stems on cut flowers
With cut flowers, you often want more length. After all, a longer stem earns more money. It is a well-known fact that stem growth is largely determined by the ratio between red and far-red light. The more far-red light (compared to red light), the taller the plants.

Using coatings, you can change the ratios between colours of light by selectively blocking a certain colour. You could therefore inhibit red light from entering the greenhouse. Even though this is technically possible, this remains a difficult approach. It is quite critical and too much far-red (compared to red) quickly leads to thin, elongated plants. Although the stems are then longer, the quality of their appearance clearly decreases.

Blue light offers more possibilities. This colour has a whole range of effects on the plant. Although it causes the stomata to open wider, it reduces their numbers on new leaves. Blue light also makes it easier for water to flow through the foliage. However, the most interesting property in this respect is that this colour inhibits stem growth.

Natural variety
ReduFlex Blue specifically inhibits blue light from entering the greenhouse, thus changing the ratio of light colours in the PAR range.
In theory, this could result in longer stems in all cut flowers. However, in a greenhouse the conditions change constantly. Firstly, there is already a lot of variation in sunlight. In spring, the proportion of blue in natural light is greater that it is in summer and when a cloud floats by in summer, there is temporarily more blue light. At dusk there is a lot of far-red, which stimulates stem growth. However, when the assimilation lighting is on at the same time, it produces so much red light that the far-red effect isn’t seen at all.

Roses love ReduFlex Blue
The combination of natural conditions and coating will produce different results in different regions. For this reason, it is a question of trying out which crops and in which regions ReduFlex Blue is able to play a useful role. In the case of roses, this has already been well demonstrated. Growers all across the world have seen positive results: in the Netherlands, Belgium, Austria, Germany, Poland, Ukraine, Russia, Kazakhstan, Ecuador and Colombia.

In many cases, an added benefit is that in summer ReduFlex Blue has a cooling effect on the greenhouse. This is due to the fact that blue light is relatively energy-rich. If you filter it out, the plant heats up less quickly. In addition, the coating has infra-red resistant properties.

For more information
Mardenkro The Netherlands
Geerstraat 8
5111 PS Baarle-Nassau
The Netherlands
T: +31 (0)13 507 70 69
Email: sales@redusystems.com

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