NEWS
HOME > NEWS
Photosynthesis and plant growth fill light
Jun 12，2022
1. Photosynthesis
The maintenance of life in nature is completely dependent on the supply of energy, and the sun is the source of energy. Plants absorb energy from the sun in photosynthesis, produce nutrients needed for plant growth through photosynthesis, and exchange carbon dioxide and oxygen with the outside world through respiration. Photosynthesis and respiration are the two main processes of plant growth.
Photosynthesis is a process in which green plants absorb sunlight energy, trigger two chemical reactions, photoaction and enzyme catalysis, absorb carbon dioxide and water in the air, produce carbohydrates, proteins, fats and other organic substances, and release oxygen at the same time.
Photosynthesis is done in the chloroplast. The chloroplasts in the plant cytoplasm contain chlorophyll and enzymes, and chlorophyll is the main substance that absorbs and transmits light energy during photosynthesis. There are two types of chlorophyll in higher plants: a and b. Chlorophyll a is blue-green and chlorophyll b is olive green. Among the red, orange, yellow, green, cyan, blue, purple and other components contained in sunlight, chlorophyll has the strongest ability to absorb red and blue light.
There are millions of green plants in nature, and the photosynthesis process in all kinds of green plants is the same. It is estimated that about 3 million tons of CO2 and 1.1 million tons of water are converted into 2.1 million tons of oxygen and 2 million tons of organic matter by photosynthesis every minute on Earth.
Second, the solar spectrum and the role of various colors of light
1) Visible light: There are three parts of sunlight, namely visible light, ultraviolet light and infrared light, which is the solar spectrum. Red, orange, yellow, green, cyan, blue, and purple light are visible light with wavelengths ranging from 700 to 400 nanometers, accounting for 71% of the total solar radiation. For the visible light part reaching the plant surface, 5% is reflected, 2.5% is transmitted through the leaves, and 42.5% is absorbed (of which about 40% is used for transpiration to consume heat, and about 2.5% is lost by the leaves through radiation, only about 0.5~ 1.0% energy for photosynthesis).
Among the visible light, the red-orange light (wavelength 600-700 nanometers) and blue-violet light (wavelength 400-500 nanometers) are most absorbed by green plants, and only a small amount of green light (500-600 nanometers) is absorbed. Substances produced under red light make plants grow taller. The substances generated under blue light promote the accumulation of proteins and non-carbohydrates and make plants gain weight.
2) Ultraviolet light: Light with a wavelength less than 400 nanometers is ultraviolet light, accounting for 7% of the solar radiation. Among them, the wavelength of 300-400 nanometers is near-ultraviolet, the wavelength of 200-300 nanometers is far-ultraviolet, and the wavelength of less than 200 nanometers is vacuum ultraviolet. High-intensity UV rays less than 300 nm are harmful to plants, and UV rays less than 280 nm can kill plants.
Most of the ultraviolet rays radiated by the sun are absorbed after passing through the atmosphere, especially the ozone layer. Very little UV light reaches the ground. The effects exhibited by UV light are often favorable. It plays an important role in the shape, color and quality of plants. High mountains and plateaus have more ultraviolet content, which makes plant stems and leaves short and darker in color. It has a good effect on fruit ripening and can also increase the sugar content of fruit. It can inhibit leggy effect, can promote the absorption of phosphorus and aluminum, and is conducive to the formation of various pigments.
3) Infrared light: The light with a wavelength of 700-3000 nanometers is infrared light, accounting for about 22% of the total solar radiation, of which 15% is reflected, 12.5% is transmitted through the leaves, and 22.5% is absorbed by the leaves. Infrared light can increase ground temperature and air temperature, providing the heat needed by plants.
In short, red light and blue-violet light are the most effective for photosynthesis of green plants. Chlorophyll in chloroplasts of green plants mainly absorbs red light and blue-violet light in sunlight, and carotenoids mainly absorb blue-violet light, which means that red light and blue-violet light are the most effective for photosynthesis.
Third, the method of adding red and blue light
1. Colored film and light conversion film
The colored film is a plastic film with organic dyes, and the light conversion film is a plastic film with organic rare earth compounds. The colored film can selectively transmit seven colors of sunlight, and the light conversion film can convert green light into red and blue light.
People can use plastic films of different colors to artificially adjust the composition of visible light. Cover seedlings with light blue vinyl plastic and grow stronger than those covered with clear film. Flowers and plants grow 50-70% higher in artificial light with twice the amount of natural light in blue light than under natural conditions; when planted in a red light environment, their growth rate is more than 40% higher than that in the control.
2. Light Emitting Diode (LED)
Light-emitting diodes are a kind of semiconductors. The light-emitting diodes have strong illumination and low power consumption. Different diode light sources have obvious effects on leaf growth, chlorophyll content and root weight of flower seedlings. Orange-red and blue-violet light are advantageous.
3. Plant lights
The main spectrum of plant lights is concentrated in the blue and red regions. Scientists found that the spectral energy distribution of this lamp is very close to the efficiency curve of plant photosynthesis (the efficiency is even more significant for green plants), and it is the best light source for plant growth. The lamps that promote plant photosynthesis use three-band lamps with wavelengths of 430 nanometers, 555 nanometers and 630 nanometers. This kind of lamp can promote the metabolism of flowers and accelerate the photosynthesis of flowers.
4. Supplementary light factors affecting plant growth
The modern agricultural factory controls and regulates the industrial process of plants by using the method of growing light in the greenhouse. The advantage of this approach is that it can get rid of the influence of natural climate change on the growth of crops, so that the entire agricultural production process is always in a controllable state.
The light factors affecting plant growth mainly include light intensity, light wavelength and light time.
Light intensity: According to botanical theory, only a certain intensity of light stimulation can cause effective photosynthesis in plants. According to the growth characteristics of different plants, the light intensity suitable for plant photosynthesis is generally 2000-5000 lux.
Light wavelength: According to botanical theory, different wavelengths of light have different effects on plant growth. On the basis of natural lighting, adding supplementary lighting of blue band and red band has a significant effect on regulating the growth of plants.
Lighting time: The photosynthesis of plants has its own rules. Generally speaking, during the day, plants absorb sunlight to produce photosynthesis. At night, plants exchange carbon dioxide and oxygen through respiration.
In the modern agricultural factories that have been built, most of them have set up lighting devices to promote plant growth, and provide supplementary light to plants through close-up illumination.
This lighting device can control the intensity and time of light through a pre-implanted program according to the needs of plant growth, thereby promoting the growth of plants.
my country is a big agricultural country. Breakthroughs in this area will not only increase crop yields and improve quality, but also make efficient use of land resources. Therefore, vigorously carry out research on the selective absorption of light band by plant growth and development, and develop and apply plant-specific lighting equipment according to the influence of different spectral components on plant growth and development, which will bring huge economic and social benefits.
The maintenance of life in nature is completely dependent on the supply of energy, and the sun is the source of energy. Plants absorb energy from the sun in photosynthesis, produce nutrients needed for plant growth through photosynthesis, and exchange carbon dioxide and oxygen with the outside world through respiration. Photosynthesis and respiration are the two main processes of plant growth.
Photosynthesis is a process in which green plants absorb sunlight energy, trigger two chemical reactions, photoaction and enzyme catalysis, absorb carbon dioxide and water in the air, produce carbohydrates, proteins, fats and other organic substances, and release oxygen at the same time.
Photosynthesis is done in the chloroplast. The chloroplasts in the plant cytoplasm contain chlorophyll and enzymes, and chlorophyll is the main substance that absorbs and transmits light energy during photosynthesis. There are two types of chlorophyll in higher plants: a and b. Chlorophyll a is blue-green and chlorophyll b is olive green. Among the red, orange, yellow, green, cyan, blue, purple and other components contained in sunlight, chlorophyll has the strongest ability to absorb red and blue light.
There are millions of green plants in nature, and the photosynthesis process in all kinds of green plants is the same. It is estimated that about 3 million tons of CO2 and 1.1 million tons of water are converted into 2.1 million tons of oxygen and 2 million tons of organic matter by photosynthesis every minute on Earth.
Second, the solar spectrum and the role of various colors of light
1) Visible light: There are three parts of sunlight, namely visible light, ultraviolet light and infrared light, which is the solar spectrum. Red, orange, yellow, green, cyan, blue, and purple light are visible light with wavelengths ranging from 700 to 400 nanometers, accounting for 71% of the total solar radiation. For the visible light part reaching the plant surface, 5% is reflected, 2.5% is transmitted through the leaves, and 42.5% is absorbed (of which about 40% is used for transpiration to consume heat, and about 2.5% is lost by the leaves through radiation, only about 0.5~ 1.0% energy for photosynthesis).
Among the visible light, the red-orange light (wavelength 600-700 nanometers) and blue-violet light (wavelength 400-500 nanometers) are most absorbed by green plants, and only a small amount of green light (500-600 nanometers) is absorbed. Substances produced under red light make plants grow taller. The substances generated under blue light promote the accumulation of proteins and non-carbohydrates and make plants gain weight.
2) Ultraviolet light: Light with a wavelength less than 400 nanometers is ultraviolet light, accounting for 7% of the solar radiation. Among them, the wavelength of 300-400 nanometers is near-ultraviolet, the wavelength of 200-300 nanometers is far-ultraviolet, and the wavelength of less than 200 nanometers is vacuum ultraviolet. High-intensity UV rays less than 300 nm are harmful to plants, and UV rays less than 280 nm can kill plants.
Most of the ultraviolet rays radiated by the sun are absorbed after passing through the atmosphere, especially the ozone layer. Very little UV light reaches the ground. The effects exhibited by UV light are often favorable. It plays an important role in the shape, color and quality of plants. High mountains and plateaus have more ultraviolet content, which makes plant stems and leaves short and darker in color. It has a good effect on fruit ripening and can also increase the sugar content of fruit. It can inhibit leggy effect, can promote the absorption of phosphorus and aluminum, and is conducive to the formation of various pigments.
3) Infrared light: The light with a wavelength of 700-3000 nanometers is infrared light, accounting for about 22% of the total solar radiation, of which 15% is reflected, 12.5% is transmitted through the leaves, and 22.5% is absorbed by the leaves. Infrared light can increase ground temperature and air temperature, providing the heat needed by plants.
In short, red light and blue-violet light are the most effective for photosynthesis of green plants. Chlorophyll in chloroplasts of green plants mainly absorbs red light and blue-violet light in sunlight, and carotenoids mainly absorb blue-violet light, which means that red light and blue-violet light are the most effective for photosynthesis.
Third, the method of adding red and blue light
1. Colored film and light conversion film
The colored film is a plastic film with organic dyes, and the light conversion film is a plastic film with organic rare earth compounds. The colored film can selectively transmit seven colors of sunlight, and the light conversion film can convert green light into red and blue light.
People can use plastic films of different colors to artificially adjust the composition of visible light. Cover seedlings with light blue vinyl plastic and grow stronger than those covered with clear film. Flowers and plants grow 50-70% higher in artificial light with twice the amount of natural light in blue light than under natural conditions; when planted in a red light environment, their growth rate is more than 40% higher than that in the control.
2. Light Emitting Diode (LED)
Light-emitting diodes are a kind of semiconductors. The light-emitting diodes have strong illumination and low power consumption. Different diode light sources have obvious effects on leaf growth, chlorophyll content and root weight of flower seedlings. Orange-red and blue-violet light are advantageous.
3. Plant lights
The main spectrum of plant lights is concentrated in the blue and red regions. Scientists found that the spectral energy distribution of this lamp is very close to the efficiency curve of plant photosynthesis (the efficiency is even more significant for green plants), and it is the best light source for plant growth. The lamps that promote plant photosynthesis use three-band lamps with wavelengths of 430 nanometers, 555 nanometers and 630 nanometers. This kind of lamp can promote the metabolism of flowers and accelerate the photosynthesis of flowers.
4. Supplementary light factors affecting plant growth
The modern agricultural factory controls and regulates the industrial process of plants by using the method of growing light in the greenhouse. The advantage of this approach is that it can get rid of the influence of natural climate change on the growth of crops, so that the entire agricultural production process is always in a controllable state.
The light factors affecting plant growth mainly include light intensity, light wavelength and light time.
Light intensity: According to botanical theory, only a certain intensity of light stimulation can cause effective photosynthesis in plants. According to the growth characteristics of different plants, the light intensity suitable for plant photosynthesis is generally 2000-5000 lux.
Light wavelength: According to botanical theory, different wavelengths of light have different effects on plant growth. On the basis of natural lighting, adding supplementary lighting of blue band and red band has a significant effect on regulating the growth of plants.
Lighting time: The photosynthesis of plants has its own rules. Generally speaking, during the day, plants absorb sunlight to produce photosynthesis. At night, plants exchange carbon dioxide and oxygen through respiration.
In the modern agricultural factories that have been built, most of them have set up lighting devices to promote plant growth, and provide supplementary light to plants through close-up illumination.
This lighting device can control the intensity and time of light through a pre-implanted program according to the needs of plant growth, thereby promoting the growth of plants.
my country is a big agricultural country. Breakthroughs in this area will not only increase crop yields and improve quality, but also make efficient use of land resources. Therefore, vigorously carry out research on the selective absorption of light band by plant growth and development, and develop and apply plant-specific lighting equipment according to the influence of different spectral components on plant growth and development, which will bring huge economic and social benefits.
