Light quality refers to the spectral composition of light that plants receive. The energy distribution of each spectrum has different effects on plants. For plant morphology, growth and development, from ultraviolet to far-red light has an effect. It has a relatively large impact on plant growth and nutritional quality.
LED grow light blue
The blue light of LED grow lights is very important. If there is no blue light, most plants will not grow normally. Plants have several different methods to measure the blue light of LED grow lights, and each method has its own effect. When you see a plant growing in the direction of the light, it only responds to the blue light of the LED grow light. Without any blue light component, the plant will not know where to grow.
The blue light of LED grow lights also affects the growth mode of stems and leaves. Plant seedlings and plants that emit blue light of LED grow lights tend to be short and strong, and they tend to grow large leaves and spread out.
The blue light and red light of the LED grow light can help the plant "know" whether it is day or night, and help set the circadian rhythm. Cannabis plants start to sag every day before the LED grow light is off, and they start to stretch when the LED grow light is on. This is a way for plants to save energy when they "sleep". Since the blue color in the LED plant light helps to "understand" the schedule, it will make the greatest preparations for the lights to go out and lights to turn on.
LED grow light red light
Of course we can see red light, but generally humans cannot see far red light, but plants can perceive red and far red light.
Red light may be the type of light most needed by plants. When it comes to photosynthesis, plants can best generate energy from red light. In fact, even if they only get pure red light, many plants can actually grow, although they will not be as big and healthy as under full-spectrum light. Each type of growth light, even blue-rich light like metal halides, can provide a considerable amount of red light.
After the seed ruptures, the shell opens, but before the shell reaches the surface, the root drops, and the growth direction of the seed is a higher red light direction than far red. Blue light usually does not make the roots penetrate deep into the ground, but the seeds can feel red from the surface and grow in that direction.
After the seed reaches the surface and is exposed to blue light, it will stop acting like a root and begin to act like a seedling, opening its leaves and growing toward the closest blue light source. If it does not get enough blue light on the surface, it will continue to grow longer and longer main stems without leaving any leaves, and its behavior is more like root growth, because it still "thinks" that it is underground, at least hidden in sunlight Down.
The seed moves towards the light, and once the plant hits the surface, the leaves inside will not open... it is looking for the right amount of light of the right color! If the plant cannot get enough light from the surface, it will stay in "root mode" and maintain a higher height without opening the leaves.
In bright sunlight, cannabis plants tend to be relatively short, because direct sunlight usually has more red than far red, and plants respond to this ratio. Therefore, if the plant gets more light at 660nm than 730nm, the stem tends to be shorter and the plant will grow many nodes with shorter stems.
If the plant gets more light at 730nm than at 660nm, it tends to grow taller and more flexible. When plants are surrounded by a lot of vegetation, the surrounding leaves will absorb a lot of red light, so no matter what light is filtered to hidden plants or stems, the proportion of far red is higher.
In response to a high level of far-red light, the stem will begin to stretch and grow taller because the plant is stretching "toward" the light until its ratio to red increases and it "feels" that it is under direct sunlight again . If the plant is surrounded by greenery, it will begin to sense a higher proportion of far-red light and begin to "stretch" upwards until it passes over other vegetation and obtains better quality light.
Far-red light is the last thing the plant "sees" at sunset, so when the far-red light level is accompanied by a period of darkness, the plant "knows" that it is night. When the plant starts to get higher levels of red and blue light from the morning sun, it "knows" that the day has begun again. If a plant is exposed to red light during a dark period, it will be "awakened" because it thinks that daylight is happening. Blue light also affects plants by disrupting their circadian rhythms.
These processes can help greenhouse farms set their own internal clocks for the plants. Tracking the night time is the main way for cannabis plants to know when they begin to bloom (sprout). When the night gets longer, it will send out a flowering response, because it "thinks" that winter is coming! Therefore, the grower only needs to change the light schedule of the plant and can force the plant to start blooming at any time!
LED grow light green light
There is a lot of research on how different spectra affect plant growth, especially in the past ten years, NASA researchers have tried to find a way to use LED grow lights to grow plants most effectively in space.
We have long known that plants need at least red and blue light to grow normally, but recent discoveries have found that although green light is not the most effective spectrum of photosynthesis, it also has an important impact on plant growth. The green light of LED grow lights has been proven to be related to the seedling and growth period as well as the beginning of the flowering period, the use of CO2/water, the growth of the stem and the height of the entire plant. There may be more we don’t know yet.
But like other spectra, plants seem to only need the right amount of green light to achieve optimal growth, rather than excessive or insufficient. After many green light experiments, NASA's biological science research team reported that a light source composed mainly of green slows the growth of plants. The combination of red and blue (including up to 24% of green) actually enhances the growth of certain plants than pure red and blue light.
Cannabis is definitely different from lettuce, which does not necessarily mean that adding green light ingredients will increase the production of cannabis! Almost all LED grow lights provide a certain proportion of green light components, adding too much green may reduce the yield. It is necessary to explore to obtain greater growth efficiency from green lighting.
Ultraviolet rays
When we talk about plants, sometimes UV-A (315 to 400 nm) and UV-B (280 to 315 nm) are classified as part of the "blue" spectrum, although in recent years, it has been found in some studies The ultraviolet spectrum has a unique effect on plants.
Plants exposed to high-intensity ultraviolet light can also be damaged, and we understand that plants can respond to ultraviolet light by producing chemicals, antioxidants and enzymes to help prevent and repair damage. They are making their own "sunscreen!" This is a bit like how our body tans us after UV exposure to protect us from further skin damage.
Some growers believe that providing UV-B light to the plant may increase the THC content or other aspects of the potency of cannabis buds. This is possible because we know that UV-B light does change the way plants grow. But we don’t know how cannabis reacts to UV-B. It may increase the level of THC, but it may also decrease it, or it may not affect THC at all. Since we have very little information today, it is difficult to know whether supplementing cannabis with extra UV-B is really beneficial.
Most LED grow lights also produce a certain amount of ultraviolet light, although it is much lower than the sun. The only exception is LED grow lights with narrow-band spectrum, which require special installation of UV diodes. There are other ultraviolet light sources.
The effect of LED grow light quality on the growth of crop roots, light can pass through the internal light environment, through the regulation of photoreceptors, and regulate its growth and development. The blue light of LED grow lights is conducive to the growth and development of plant roots. The cultivated rice seedlings were irradiated with the blue light of the LED grow light, and it was found that the protein content accumulated in the root system of the rice seedlings was high, the non-protein nitrogen content was low, the ratio of protein nitrogen to total nitrogen was high, and the total nitrogen content was also high. The synthesis of nitrogen compounds in the root system of the seedlings, the production of protein accumulates in the root system. Seedling raising based on the blue light effect of LED grow lights on crop roots has been applied by reproducers.
The effect of LED grow light quality on leaf growth, leaves are the main organs for photosynthesis of plants, and the change of LED grow light quality directly affects leaf growth. The leaf area of birch seedlings grown under blue light is twice that of seedlings under red light, and the leaf epidermal cell area, palisade tissue, sponge tissue and functional chloroplast area are larger than those under white light and red light. Studies have also shown that increasing the proportion of LED red light in the compound light has a certain promotion effect on the increase of tobacco leaf area, but the leaf weight of the leaf is reduced, and the leaf becomes very thin.
The influence of the light quality of the LED grow light on the regulation of the stoma. The stoma is the channel for water and oxygen to enter and exit, and the gateway for plant photosynthesis. Stomatal movement is regulated by many external environmental factors and internal factors, of which light is an important regulating factor. It is found in both monocot and dicot plants that the blue light of LED grow lights can promote the opening of stomata. The principle that the blue light of LED grow lights promotes the opening of stomata, that is, the blue light activates the plasma membrane ATPase to continuously pump protons to form a transmembrane electrochemical gradient ,
The effect of the light quality of the LED grow light on the growth of crop stems. Different wavelengths of light can regulate the growth of the stems by affecting the level of endogenous hormones in the plant. Blue-violet light can increase the activity of indole acetic acid oxidase and reduce the level of auxin, thereby inhibiting the growth of plants. At the molecular structure level, red light can promote cell elongation, while blue light has the opposite effect. In general, the long-wavelength LED grow light red light promotes the elongation of the stem, while the short-wavelength light inhibits the elongation of the stem.
The effect of LED grow light quality on the photosynthetic characteristics of plants has a regulatory effect on the synthesis of chlorophyll. According to the needs of planting plants, the light quality is matched and supplemented to give the plants a better growth state.
