Effects of LED lamps with different light qualities on plant growth quality
Light quality has great influence on plant growth and development, photosynthetic characteristics, yield and quality. The results showed that green light and red light obviously promoted the elongation of stem of color sweet pepper seedlings. Blue light had Dwarfing Effect on seedlings. The effect of compound light was better than that of monochromatic light. Red light is not conducive to the increase of chrysanthemum stem, red light treatment of stem length is 43.0% less than the control; there are also reports that red light is conducive to the thickening of chrysanthemum plant stem. Increasing the ratio of blue light to red light could effectively reduce the plant height of cucumber seedlings. Increasing the ratio of red light could make more photosynthate transported to the leaves of cucumber seedlings. Chlorophyll a, chlorophyll b and carotenoids of lettuce increased with the increase of blue light. The content of chlorophyll in plants was significantly increased by blue light treatment or increasing the proportion of blue light. It is suggested that the higher proportion of blue light intensity may be beneficial to the synthesis of photosynthetic pigments. The photosynthesis of plants with 7% blue light in the combination of red and blue light could operate normally. With the increase of the proportion of blue light, the photosynthetic capacity of leaves also increased, but the photosynthetic capacity of leaves decreased after the proportion of blue light exceeded 50%.——LED Growth lamp
Under the single red light, more dry matter was accumulated, the internodes were longer, the stem was smaller, the leaves were smaller, and the total sugar content was higher. The soluble sugar content of cucumber seedlings treated with red light was the highest, while the soluble protein content of cucumber seedlings treated with blue light was the highest. The chlorophyll content, stomatal conductance and transpiration rate of tomato seedlings treated with red light increased, and the photosynthetic rate was significantly higher than that of other treatments. The chlorophyll content of tomato seedlings treated with blue light was slightly lower, but the photosynthetic rate was still significantly higher than that of control. The reason may be that blue light promoted stomatal opening and increased the intercellular CO2 concentration of leaves. The increase of stomatal conductance of plants was induced by blue light.——LED Growth lamp
For most plants, red light has a promoting effect on leaf area. Under red light treatment, the leaves of radish seedlings, toon seedlings, tomato, cucumber seedlings, tobacco, herb poison and lettuce expanded faster and the leaves were larger. Blue light can also increase leaf area, but blue light inhibits leaf expansion of tobacco, poinsettia and mosaic. Blue light added to red light can significantly increase the leaf area of lettuce. The area of spinach leaf treated with red, blue and yellow light was significantly larger than that of other treatments. Red light treatment was beneficial to dry matter accumulation of tomato, eggplant, cucumber, lettuce and other crops. Red and blue composite light increased biomass of chilli, Phalaenopsis, vetch and cucumber. The biomass of lettuce, cherry tomato and Non-heading cabbage was significantly affected by adding green light, yellow light, purple light and white light on the basis of red and blue light combination.——LED Growth lamp
Red light is beneficial to carbohydrate accumulation in plants. The soluble sugar content of spinach, cucumber, hot pepper, tomato seedlings and radish sprouts could be significantly increased by red light treatment. Red light can promote the accumulation of starch, which has been reported in soybean, cotton, oil sunflower sprouts and Brassica napus and other crops. Because the output of photosynthates in leaves can be inhibited by red light, so starch accumulates in leaves. The change of soluble protein content in leaves is one of the reliable indicators reflecting physiological functions of leaves. Blue light is conducive to protein synthesis. Blue light promoted the soluble protein content of pea seedlings, lettuce, cucumber and sprouts. Blue light significantly increased the total amino acid content and sugar content of chrysanthemum leaves. Current studies have shown that blue light can significantly promote dark respiration of mitochondria, and organic acids produced during respiration can be used as carbon scaffolds for amino acids synthesis, thus facilitating protein synthesis.——LED Growth lamp
Compound spectra also promoted the photosynthetic products of plants. Yellow light was beneficial to the synthesis of soluble sugar and protein in lettuce, the formation of sucrose content in tomato and the accumulation of free amino acids in rapeseed sprouts. Low dose UV-B and red light compounded significantly increased sugar content in tomato. Blue light and UV-A can promote the protein synthesis of cucumber fruit. The combination of blue and red light promoted the accumulation of soluble and soluble proteins. Red, blue and white light promoted the synthesis of soluble sugar and nitrogen. The total starch content of tomato seedlings treated with red, blue and green light was the most. SOD, as an endogenous scavenger of reactive oxygen species (ROS) in plants, can effectively scavenge ROS and keep it at a low level, thus reducing its damage to membrane structure and function.
The results showed that SOD activity of Color Sweet Pepper Seedlings under green light was the highest, but there was no significant difference between blue light and red light; POD was a scavenger of reactive oxygen species (ROS), and POD activity was the lowest under green light. White light had the highest CAT activity, followed by blue light, green light had the highest CAT activity, yellow light and red light had the same activity. Purple light and blue light can alleviate the senescence of Cucumber Seedlings by increasing the activity of CAT and other antioxidant enzymes and their gene expression, delaying the degradation of chlorophyll and soluble protein and membrane peroxidation.——LED Growth lamp
Red and blue light are the main light sources for plants to absorb, and they are also the signal source of the main photoreceptors in plants. Under the condition of weak light, supplementing light with LED red and blue light source can effectively control the elongation of cucumber seedlings, improve the quality of seedlings, and alleviate the damage of physiological stress under weak light. Red and blue composite light promoted biomass accumulation of seedlings and lettuce plants in pepper and rice. The red and blue combination light source, which is 60% of Blu ray, may be the better source of cherry tomato fruit quality. The leaf area value of Tomato Seedlings under red/blue (2:1) light supplementation was the largest, but the leaf area value under red/blue (7:1) light supplementation was relatively small in red and blue light, indicating that the increase of red light proportion could only promote leaf growth in a certain range.——LED Growth lamp
Red light is beneficial to the radial growth of stem and leaf of rapeseed, and the appropriate increase of blue light ratio is beneficial to the lateral growth of stem and leaf, root development and photosynthetic pigment synthesis, plant lodging is not easy, and can improve leaf photosynthesis, transpiration and fluorescence characteristics, thereby promoting the growth of rapeseed, and increasing biomass and nutrient content. The content of soluble protein in cucumber seedlings decreased under low light, and increased significantly after red and blue light supplementation. The content of soluble sugar and soluble protein in tomato seedling leaves reached the maximum under red/blue (2:1) light supplementation. Red and blue LED mixed light source treatment of gourd and pumpkin seedlings developed root system, high dry matter content, strong seedling index increased, seedling quality improved; red and blue LED mixed light components increased, inhibited the elongation of seedling stem, promoted the increase of seedling stem diameter.——LED Growth lamp
The cotyledon area, soluble sugar, starch, carbohydrate, sucrose and C/N of lettuce seedlings under red and blue light were the largest and significantly higher than those under red light, indicating that adding appropriate amount of blue light to red light was more conducive to the accumulation of carbohydrates in lettuce seedlings. 25% and 50% Blu-ray treatments were beneficial to the accumulation of biomass, the content of photosynthetic pigments, the larger leaf area, the thicker leaves, and the photosynthesis of lettuce. The content of chlorophyll in strawberry leaves was greatly affected by R / B ratio, and the content of chlorophyll in strawberry leaves was significantly reduced by blue light. The chlorophyll content of lettuce was regulated by 660 nm red light and 450 nm blue light. With the increase of blue light and the decrease of red light, the contents of chlorophyll a and chlorophyll b decreased gradually. The net photosynthetic rate and stomatal conductance of cucumber seedlings treated with red and blue light were the highest, while the net photosynthetic rate, stomatal conductance and transpiration rate of cucumber seedlings treated with single red and blue light were lower, but the intercellular CO2 concentration was higher. The activities of SOD, CAT and other antioxidant enzymes increased first and then decreased with the increase of red light ratio, while the activities of SOD decreased under R / B (2:1) supplementation.——LED Growth lamp
Most studies have shown that blue light can reduce plant fresh weight and dry weight. With the increase of blue light, the dry weight and fresh weight of lettuce increased first and then decreased. At different growth stages, the effect of blue light on the biomass was different, but the increase of biomass in early growth stage was inversely proportional to the red / blue value, and was directly proportional to the red / blue value in late growth stage. Blue purple light inhibited the elongation of stems. Compared with white light, blue purple light significantly reduced plant height and increased stem diameter. In light quality on the root system, studies have shown that blue and purple light treatment of oat roots more roots, root development.——LED Growth lamp
It was found that the combination of red and blue (1:1) could significantly improve the growth and quality of lettuce, and red and blue (7:3) was the most suitable light quality condition for cucumber seedling growth, and the maximum photosynthetic rate could reach four times that of monochromatic red light. When red / blue was 8: 1, lettuce showed obvious photosynthetic advantage. Adding yellow light on the basis of red and blue light was beneficial to the synthesis of photosynthetic pigments in spinach, and promoted the growth of spinach significantly. Adding yellow light and purple light could improve the photosynthetic potential of cherry tomato seedlings and alleviate the red and blue light stress.——LED Growth lamp
Effect of light quality on vegetable quality
Light quality can affect many physiological processes of plants, especially in photosynthesis and plant morphogenesis. Rational use of specific light waves is conducive to improving vegetable nutritional quality.
It is generally believed that red light is conducive to the accumulation of carbohydrates, can promote the synthesis of soluble sugar, but not conducive to the accumulation of soluble protein; and blue light can promote the formation of protein. Red and blue light helps to reduce the amount of nitrate absorbed. The soluble sugar content of lettuce was higher under blue light or red blue light treatment. Compared with white light, red and blue light treatments significantly reduced nitrate content in the aerial parts of lettuce. Under the same light intensity and duration, red, blue and white mixed LED illumination could reduce more nitrate content in Hydroponic Lettuce than red and blue illumination; under the white light condition, the treatment supplemented with blue light or green light reduced nitrate content in lettuce.——LED Growth lamp
Different light qualities have different effects on the formation of secondary metabolites in plant organs. Red light, blue light and red-blue mixed light can promote the degradation rate of chlorophyll and increase the synthesis rate of carotenoids and anthocyanins, but slow down the synthesis rate of flavonoids. Blue light could induce the accumulation of flavonoids and anthocyanins. Increasing the proportion of blue light could promote the formation of lycopene and flavonoids in tomato fruits. Adding UV-B and blue light at night to lettuce can increase quercetin content in lettuce. The contents of anthocyanins and carotenoids in leaves of lettuce supplemented with ultraviolet light and blue light were significantly increased; the contents of chlorophyll in lettuce were increased by blue light, and the contents of total phenols and flavonoids and antioxidant capacity were the highest in leaves of lettuce supplemented with blue light at night. The highest content of anthocyanin in the aerial part of lettuce under blue light treatment. Red light: white light: blue light for 8:1:1 treatment increased the total anthocyanin content of Perilla frutescens. The total phenolic content of red, purple and green lettuce was the highest under red and blue light or white light, the content of flavonoids and anthocyanins was the lowest under red light, and the content of anthocyanins was the highest under red and blue light. 100% blue light could significantly increase the fresh weight of the raw menu plants, and vitamin C content was 2.25 times higher than that of the control. The total phenolic content of basil treated with 20% blue light, 39% green light, 35% red light, 5% far red light and 1% ultraviolet light was significantly higher than that of other treatments.——LED Growth lamp
A large number of studies have shown that the effect of red and blue light combination on plant nutritional quality is significantly higher than that of monochromatic light. Compared with white light, the content of vitamin C in lettuce and Komatsu vegetables increased significantly under blue light or red and blue light treatment. Under controlled environmental conditions, red and blue light is the most suitable light treatment for increasing the content of perillaldehyde, limonene and anthocyanin in Perilla frutescens. The chlorophyll content, total phenol content, total flavonoids content and antioxidant capacity of green lettuce and red lettuce were significantly increased when a certain proportion of blue light (59%, 47% and 35%) was added to the red light. Compared with white light treatment, red and blue compound light could increase the content of soluble protein in celery, but decrease the content of nitrate. Soluble sugar in eggplant meat and total phenol, red pigment, yellow pigment and total antioxidant capacity in eggplant skin were also improved. Compared with white light, red-blue combination light (1:1) increased the content of soluble sugar and lycopene, red-blue combination light (3:1) significantly increased the content of free amino acids and soluble protein. Compared with other treatments, 70% red light + 30% blue light could significantly increase the fresh weight, chlorophyll and carotenoid content of fresh menu plants.——LED Growth lamp
Green light and yellow orange light, although there are not many reports and studies, also have important physiological effects on vegetables. Different light quality had different effects on photosynthetic pigments of lettuce, and the content of beta carotene was the highest under green light. Supplementary orange light increased the content of total phenols in rapeseed, and supplementary green light increased the content of alpha-carotene and anthocyanin. Supplemental green light can promote the accumulation of soluble sugar in lettuce, and also reduce nitrate content.——LED Growth lamp
UV and infrared light also had certain effects on the quality of vegetables. The vitamin C content of pea seedlings did not change after supplementation with UV-C (254 nm), but decreased significantly after supplementation with UV-A (365 nm), but increased the content of flavonoids. The light source without UV-B can significantly reduce the content of oxalic acid in sugar beet compared with the control. Supplementation of ultraviolet light enhanced the content of phenolic compounds and alpha carotene in lettuce. The content of ascorbic acid was the lowest in spinach irradiated with 6 kJ M 2 UV B every day, and the anthocyanin content was higher in spinach irradiated with 4 kJ M 2 UV B. After UV-A and UV-B treatment, the anthocyanin content of purple cabbage and green cabbage increased significantly, and UV-B treatment was more effective than UV-A treatment in improving the anthocyanin content, which was closely related to the increased expression of downstream structural genes in anthocyanin biosynthesis under UV irradiation. UV-A irradiation significantly increased the activity of antioxidant enzymes in radish sprouts, and increased the expression of genes related to L-galactose pathway and the activity of GLDH enzymes. Anthocyanidins, carotenoids and chlorophyll contents in lettuce leaves were significantly decreased under far infrared irradiation. Supplementation of far-infrared light promoted the accumulation of vitamin C in lettuce, and reduced biomass and pigment content. The contents of total phenol, chlorogenic acid and caffeic acid in lettuce were significantly increased by adding far infrared light on the basis of red and blue light.——LED Growth lamp
For sprouts, it is generally believed that blue-purple light can make seedlings robust, but also promote the accumulation and synthesis of antioxidant substances. Supplementary UV-A and blue light could increase anthocyanin content, blue light could increase carotenoid content, red light could increase total phenol content, while far red light could decrease anthocyanin, carotenoid and total phenol content. Red and blue light treatment could increase the content of vitamin C in pea seedling leaves. The content of carotenoids in stem and leaf of pea seedling was higher under white light and red and blue light treatment, and the content of anthocyanin was the highest under white light treatment. UV-B irradiation for 24 hours could promote the accumulation of kaempferol and quercetin in broccoli sprouts, and UV-B could induce the synthesis of glucosinolates (GS). UV-B and blue light can increase the content of total phenolic substances in radish sprouts and improve the antioxidant capacity of radish sprouts. The contents of chlorophyll a, chlorophyll b and total chlorophyll were the highest under red LED irradiation, and the accumulation of vitamin C was promoted by blue LED irradiation. Compared with white light, the content of amino acid, vitamin C and total flavonoids in Toona sinensis sprouts could be increased and the content of nitrate, crude fiber and tannin could be decreased by blue light and red-blue light. Blue light treatment was beneficial to increase the content of protein and carotenoids, promote the synthesis of vitamin C, and reduce the content of crude fiber in pea sprouts. Red light treatment can reduce chlorophyll, soluble sugar and crude fiber, but inhibit vitamin C synthesis.——LED Growth lamp
As the largest country in the world, China urgently needs to develop LED lamps, LED lighting automatic control system and LED regulator to meet the needs of facility horticulture (including tissue culture, Factory Seedling raising, greenhouse lighting, artificial light production and so on). With the development of LED technology and the decrease of production cost year by year, especially with the development of plant photobiology research, the theoretical basis of plant lighting application technology is constantly strengthened and improved. Various technologies and products related to LED plant lighting will be widely used in the production practice of facility horticulture.——LED Growth lamp
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