Effects of spectral range on Plant Physiology

·280 ~ 315nm – “this wavelength belongs to ultraviolet light. It has the function of directly suppressing the growth of all kinds of animals, plants and even fungi, and has little impact on morphological and physiological processes.

·315 ~ 400nm – “this kind of light wave also belongs to far ultraviolet light. Although there is no ultraviolet damage to plants, it has no direct effect on plant growth. It absorbs less chlorophyll, affects the photoperiodic effect and prevents stem elongation.

·400 ~ 520nm (blue) – “these wavelengths can directly promote the development of plant roots and stems, with the largest absorption ratio of chlorophyll and carotenoids and the greatest impact on photosynthesis.

·520 ~ 610nm (green) – green plants repel pushing, and the absorption rate of green pigment is not high.

·610 ~ 720nm (red) – the chlorophyll absorption rate of plants is not high, but this wavelength has a significant effect on Photosynthesis and plant growth rate.

·720 ~ 1000nm – “these wavelengths are generally infrared wavelengths, which have low absorption rate for plants, can directly stimulate cell elongation, and will affect flowering and seed germination.

·> 1000nm – “is close to the wavelength of laser light and has been converted into heat.

According to the above plant and spectral data, the influence of grow light of each wavelength on plant photosynthesis is different. Among the light required by plants for photosynthesis, 400 ~ 520nm (blue) light and 610 ~ 720nm (red) light contribute the most to photosynthesis, while 520 ~ 610nm (green) light has a low efficiency ratio for plants to exercise growth.

According to the above principle, plants only have the effect of directly helping the growth of the spectrum of 400 ~ 520nm (blue) and 610 ~ 720nm (red), so the plant grow lights under the academic concept are made into three forms: red blue combination, all blue and all red, so as to provide light lines with two wavelengths of red and blue, which are used to cover the wavelength range required for photosynthesis of plants.

On the visual effect, the red and blue combination of LED plant grow lights appear pink, which is very uncomfortable for biological lighting, but it can only be practical in its appearance and choose its practicality.

For general white LED beads, the most common is to use a blue core to excite the yellow phosphor to emit light, so as to compound and produce a visual white light effect. In the energy distribution on the integrating sphere test report, there are two peaks in the blue region of 445nm and the yellow green region of 550nm.

The 610 ~ 720nm red light required by plants is less covered, which can not supply light and the light efficiency required for their planting plants. This explains why under the irradiation of white LED, the growth speed and harvest effect of plants are not as good as ordinary outdoor planting.

Using the above data, the chromatographic ratio of red and blue lamp of general plant lamp is generally between 5:1 and 10:1, and the ratio of 7 ~ 9:1 can be selected. Only the proportion distribution needs to adopt the lamp bead brightness ratio as the light mixing basis, and the number of no grow lamp beads is the light mixing basis.

When LED grow lights are used in plant planting, the height of the leaves is generally about 30-50 centimeters, which needs to be given different light intensity according to the plant species. Adjusting the height is generally regarded as the most convenient way to adjust the brightness.