What kind of light do LED Grow Lights emit, and what effects do these lights have on the growth of plants, the answer is directly given below:
Among the visible light, the red-orange light (wavelength 600~700nm) and blue-violet light (wavelength 400~500nm) are most absorbed by green plants, and only a small amount of green light (500~600nm) is absorbed. Red light is the earliest light quality used in crop cultivation experiments, and it is necessary for the normal growth of crops.
The number of biological requirements ranks first among various monochromatic light qualities, and it is the most important light quality in artificial light sources. Substances produced under red light make plants grow taller, while those produced under blue light promote the accumulation of proteins and non-carbohydrates, giving plants weight gain.
Supplementing far-infrared infrared rays reduced the concentrations of anthocyanins, carotenoids and chlorophyll by 40%, 11% and 14%, respectively, and increased the fresh weight, dry weight, stem length, leaf length and leaf width of the plant by 28%, 15%, and 15%, respectively. 14%, 44% and 15%.
Red light regulates photomorphogenesis through phytochromes; red light drives photosynthesis through photosynthetic pigment absorption; red light promotes stem elongation and carbohydrate synthesis, which is beneficial to the synthesis of VC and sugar in fruits and vegetables; but inhibits nitrogen assimilation. It is still a bit difficult to cultivate plants well with red light alone.
Blue light is the necessary supplementary light quality for red light for crop cultivation, and it is the necessary light quality for the normal growth of crops. The biological amount of light intensity is second only to red light. Blue light inhibits stem elongation, promotes chlorophyll synthesis, is beneficial to nitrogen assimilation and protein synthesis, and is beneficial to the synthesis of antioxidant substances.
Blue light affects phototropism, photomorphogenesis, stomatal opening, and leaf photosynthesis in plants. The LED red light supplements the LED blue light to improve the dry matter quality, numerosity and seed yield of wheat, and increase the dry matter quality of lettuce. Blue light significantly inhibited leaf lettuce stem growth.
Adding blue light to white light can shorten internodes, reduce leaf area, reduce relative growth rate and improve N/C efficiency. Blue light is required for chlorophyll synthesis and chloroplast formation in higher plants, as well as for having high chlorophyll a/b ratios and low chloroplasts.
Excessive blue light is not conducive to plant growth and development. The combined spectrum of red and blue light can promote the growth and development of vegetable seedlings more than red light or blue light monochromatic light. Different plants need different ratios of red and blue light.
Green light and red and blue light can harmoniously adjust and adapt to the growth and development of plants. Generally, under the red and blue LED compound light, the plant is slightly purple-gray, which makes the disease and disorder symptoms difficult to diagnose, which can be solved by adding a small amount of green light.
The green light effect is usually opposed to the red and blue light effect, for example, green light can reverse the blue light-promoted stomatal opening, etc. Under strong white light, the photosynthetic quantum yield of the upper chloroplasts on the near-illuminated surface was lower than that of the lower chloroplasts.
Because green light penetrates the leaves more than red and blue light under strong white light, the lower chloroplast absorbs additional green light to increase leaf photosynthesis to a greater extent than the additional absorption of red and blue light.
Green light may not be considered for low-light intensity cultivated plants, green light is not considered for low-density and low-canopy-thickness facility plants, and green light must be considered for high-light-intensity, high-density, and high canopy thickness.
4. Yellow and orange -ray
Yellow light, orange light, green light, and violet light are all important photosynthetically active radiations, but plants require less light. Adding yellow light on the basis of red and blue light can significantly improve the growth of spinach seedlings.
Yellow light had the best effect on improving the nutritional quality of leaf lettuce, but blue light was more beneficial to significantly improve the content of mineral elements in lettuce. Adding yellow light and purple light can improve the photosynthetic capacity of cherry tomato seedlings and relieve the red and blue low light stress.
Compared with white light, violet light and blue light increased the activity of antioxidant enzymes and delayed the senescence of plants, while red light, green light and yellow light inhibited the activity of antioxidant enzymes and accelerated the senescence process of plants.
5. Far red-ray
Although far-red light at 730 nm has little significance for photosynthesis, its intensity and its ratio to 660 nm red light play an important role in the morphogenesis of plant height and internode length. Plant morphology and plant height were controlled by light quality regulation, R/FR ratio.
When the ratio increases, the spacing between the stem nodes of the plant becomes smaller, the plant becomes dwarfed, and the propagating plant tends to elongate. The selective absorption of red light and the selective transmission of far-red light by plants make the plants located in the shade in a far-infrared-enriched light environment.
6. Ultraviolet light (UV)
The wavelength band less than 380nm is called ultraviolet light. According to the physical and biological characteristics of ultraviolet rays, the wavelengths of 320-380 nm are long-wave ultraviolet (UV-A), medium-wave ultraviolet (UV-B) with wavelengths of 280-320 nm, and short-wave ultraviolet (UV-C) with wavelengths of 100-280 nm.
95% of the UV species reaching the ground is UV-A. In the sunlight spectrum, photosynthetically active radiation, UV and far-red light have regulatory functions on plant growth and development. UV radiation reduces plant leaf area, inhibits hypocotyl elongation, reduces photosynthesis and productivity, makes plants vulnerable to pathogens, but induces flavonoid synthesis and defense mechanisms.
Under the environment of low UV-B radiation, it will cause leggy plants and hinder the synthesis of phytochromes, making it difficult to cover nightshade vegetables. An important feature of plant factories is the lack of UV-A and UV-B radiation in sunlight.
The complete lack of UV radiation will bring negative effects on production and affect plant growth and development. Therefore, it is necessary to regulate the level of UV radiation in plant factories. , it should be noted that it is based on production demand and plant tolerance response law.
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