The solar spectrum is a continuous spectrum, in which the blue and green spectra are stronger than the red spectra, and the visible spectrum ranges from 380 to 780 nm. The growth of organisms in nature is related to the intensity of the spectrum. For example, in the equatorial region, most plants grow very fast and grow in larger size. However, the higher the irradiation intensity of the sun, the better. It is selective for the growth of plants and animals. Several key auxins affecting plant growth differ significantly in light absorption spectra. Therefore, the application of LED plant growth lamp is not a simple matter, but very targeted. Here it is necessary to introduce the concepts of two most important elements of photosynthesis plant growth.
Chlorphyll is one of the most important pigments related to photosynthesis. It exists in all photosynthetic organisms, including green plants, prokaryotic cyanobacteria and eukaryotic algae. Chlorophyll absorbs energy from light, which is then used to convert carbon dioxide into carbohydrates. Chlorophyll a mainly absorbs red light, chlorophyll b mainly absorbs blue and purple light, mainly to distinguish between shade plants and sun plants. The ratio of chlorophyll b to chlorophyll a of shade plants is small, so shade plants can make strong use of blue light to grow in shade. Chlorophyll a is blue-green and chlorophyll b is yellow-green. There are two strong absorption bands of chlorophyll a and chlorophyll b, one in the red region with wavelength of 630-680 nm and the other in the blue-violet region with wavelength of 400-460 nm.
Carotenoids (carotenoids) are a group of important natural pigments. They are commonly found in yellow, orange red or red pigments in animals, higher plants, fungi and algae. So far, more than 600 natural carotenoids have been found. Carotenoids absorb light ranging from OD303 to 505 nm, which provides food color and affects human food intake; in algae, plants and microorganisms, they cannot be presented because their color is covered by chlorophyll. In plant cells, carotenoids not only absorb and transfer energy to help photosynthesis, but also protect cells from being destroyed by stimulated single electron bond oxygen molecules.
Different wavelengths of light have different effects on plant growth.
Blue-violet light and blue light in visible light play an important role in plant growth and bud formation. This kind of light energy keeps the plant elongating and makes it form a short and thick shape. At the same time, blue-violet light is also the most important light controlling cell differentiation. Blue-violet light can also affect the phototropism of plants. Ultraviolet radiation inhibits the formation of some growth hormones in plants, thus inhibiting the elongation of stems. Ultraviolet radiation can also cause phototropic sensitivity and promote the formation of anthocyanins as blue, purple and blue light in visible light. The red and visible light in visible light can promote the germination of seeds or spore and the elongation of stems. Red light can also promote the decomposition of carbon dioxide and the formation of chlorophyll.
The influence of spectra on Photosynthesis of plants has great influence on the light of plants, mainly in three categories. Ultraviolet, visible and infrared rays.
Plants are most sensitive to red light spectrum, less sensitive to green light, and the most sensitive region is 400-700 nm. The spectrum of this region is usually referred to as the effective energy region of photosynthesis. About 45% of the energy of sunlight lies in this spectrum. Therefore, if the artificial light source is used to supplement the amount of light, the spectral distribution of the light source should also be close to this range. When we know the effect distribution of spectral wavelength on photosynthesis, we can get the accurate index of photosynthetic active radiation (PAR) by spectral radiometer. At present, the LED plant light source can be configured according to the most effective spectrum of photosynthesis. It is the most efficient plant light source. Led lighting plant lights need to be in accordance with the growth pattern of plants. The plant supplemental light is a kind of lamp which provides the better growth and development environment by using the principle of sunlight and lighting instead of sunlight.