The traditional view is that only light in the 400-700nm band will affect the photosynthesis of plants. Therefore, regardless of PPF or PPFD, only the micromolar number of photons in the 400-700nm range is calculated.
But is it the real? For example, does far-red light such as 730nm really have no effect on plant photosynthesis ? Scientists did an experiment.
Grow lettuce in 4 different grow boxes, including:
#Box 1 : PPFD=300umol/m2/s white light
#Box 2 : PPFD=350umol/m2/s white light
#Box 3 : PPFD=300umol/m2/s blue-red light
#Box 4 : PPFD=350umol/m2/s blue-red light
If we only look at the above data, it's easy to think that the harvest of the boxes No. 2 and No. 4 will be better than that of the boxes No. 1 and No. 3.
But the truth is the opposite.
After dewatering and weighing the lettuce in 4 boxes, if the dry weight of lettuce in box 4 is 100, the dry weight of lettuce in the other three boxes is 135, 100 and 127, respectively.
This also means that the harvest of Box 1 is 135% of that of Box 2 and Box 4.
How does this happen?
The reason is simple, because the far-red light is added to both box 1 and box 3.
The experiment proved that although far-red light will not be calculated into PPF or PPFD, it will actually affect the photosynthesis of plants.
As for the reason, scientists believe that the presence of far-red light can increase the rate of photosynthesis of plants and other light, resulting in an Emmerson enhancement effect.
Not only the lettuce, the scientists also conducted similar experiments on more than 20 kinds of different plants, including spinach, basil, kale, wheat, corn and sunflower, etc., and obtained the same results, effectively proving the effect of far-red light on plants. .
In addition to promoting photosynthesis in plants, there's also evidence proved that far-red light can induce early flowering of plants. For plant varieties whose commercial value is mainly concentrated in flowers, such as medical marijuana, it can shorten the growth cycle and improve the ROI.
All in all, this is why the All-In-One light source of Ultra Plant grow light, in addition to white light, red light, 405nm and 365nm, also contains 730nm far-red light.
More information, welcome to visit:https://www.ultraplantled.com/730nm-led-grow-light/
