How the Lighting Spectrum Affects Plant Growth

In order to facilitate the study of the chromatic properties of light, the visible spectrum is enclosed into a circle and divided into nine regions (see figure), which are called color rings. The number on the color ring indicates the wavelength of the corresponding color light, the unit is nanometer (nm), and the color in any two pairs of top position sectors on the color ring is called complementary color. For example, the complementary color of the led plant growth lamp blue (435 to 480 nm) is yellow (580 to 595 nm).

It has been found through research that the shade has the following characteristics: (1) The complementary colors are mixed in a certain ratio to obtain white light. White light is obtained by mixing blue light and yellow light. Similarly, the combination of cyan and orange light is also white light; (2) any color on the color ring can use two kinds of monochromatic light on the adjacent sides, and even two kinds of monochromatic light from the next nearest neighbor Mix and copy it out. Such as yellow light and red light mixed to get orange light. More typically, red and green light are mixed into yellow light; (3) if three independent monochromatic lights are selected on the color ring. It can be mixed in different proportions into various shades that may appear in daily life. These three monochromatic lights are called three primary colors of light. The three primary colors in optics are red, green, and blue. It should be noted here that the three primary colors of the pigment are red, yellow and blue. However, the choice of the three primary colors is completely arbitrary; (4) When the sunlight illuminates an object, the light of a certain wavelength is absorbed by the object, and the color (reflected light) displayed by the object is the complementary color of the color light. If the sun shines on the object, if the object absorbs violet light with a wavelength of 400 to 435 ntn, the object appears yellow-green. It should be noted here that some people say that the color of an object is that the object absorbs other colored light and reflects the light of this color. This statement is wrong. For example, the yellow-green leaves actually absorb only the violet light with a wavelength of 400 to 435 urn, and the yellow-green color is the mixed effect of other colored light reflected, instead of only reflecting the yellow-green light.

1. The spectral range of LED plant growth lamps affects plant physiology

280 ~ 315nm: minimal impact on morphology and physiological processes

315 ~ 400nm: less chlorophyll absorption, affecting photoperiod effect and preventing stem elongation

400 ~ 520nm (blue): chlorophyll and carotenoid absorption ratio is the largest, the greatest impact on photosynthesis

520 ~ 610nm (green): the absorption rate of the pigment is not high

610 ~ 720nm (red): low chlorophyll absorption rate, significant effect on photosynthesis and photoperiod effect

720 ~ 1000nm: low absorption rate, stimulate cell elongation, affect flowering and seed germination

>1000nm : Converting to heat

2. From the above data, the light required for plant photosynthesis is about 400 ~ 720nm. Light from 440 to 480 nm (blue) and 640 to 680 nm (red) contribute the most to photosynthesis. Light from 520 to 610 nm (green) is absorbed by plant pigments at a very low rate.

3. According to the above principle, the plant growth lamps are basically made into three forms of red and blue combination, all blue and all red, covering the wavelength range required for photosynthesis. In terms of visual effects, the red and blue combination plant lights appear pink. In particular, it is pointed out that white light is similar to green light in photosynthesis, and it has no effect on the influence of different spectral components of LED plant lights on plants.

4, the red and blue light chromatogram ratio of the plant lamp is generally between 5:1 ~ 10:1, usually the ratio of 7 ~ 8:1 can be selected. Of course, it is conditioned to adjust the ratio of red and blue light to the plant growth cycle.

5. When using the plant fill light to fill the plant, the height of the blade is generally 0.5 ~ 1 meter.

One thought on “How the Lighting Spectrum Affects Plant Growth

  1. Anna Summers says:

    This was interesting information about the light and why they are the colors that they are. I will look forward to reading more of your blogs as I am interested in the whole realm of the grow industry at the moment. Thank you for the insight.

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