The use of LED grows lights has seen a substantial increase in the planting industry recently. However, choosing the right spectra for plants and understanding how they affect photosynthesis can be challenging and often confusing.
This article aims to help you understand the spectrum required for plant growth and how full-spectrum LED lighting is now widely used in crop production. We will discuss what broad-spectrum lighting is, how different growth spectra affect different stages of plant growth and its impact on cannabis production.
The growth spectrum refers to the electromagnetic wavelength of the light generated by the light source to promote plant growth. For photosynthesis, plants use light in the PAR (photosynthetically active radiation) region of wavelengths (400nm-700nm) measured in nanometers (nm).
Nano is a universal unit of measurement, but it is also used to measure the spectrum-humans can only detect the wavelength of the visible spectrum ( 380-740nm ). On the other hand, plants can detect wavelengths, including our visible light, and longer wavelengths, including ultraviolet and far-red spectrum.
It is important to note that the effect of the spectrum on plant growth depends on environmental conditions, crop types, etc. Typically, the plant chlorophyll is responsible for the light energy into chemical energy of molecules, blue and red absorption spectrum, most of the light for photosynthesis. In PAR found peaks of red and blue range.
LED grow lights are energy-saving lamps used by indoor and greenhouse farmers and cannabis growers. LED is used as the sole light source (indoor) or supplementary light source (greenhouse), using full-spectrum lighting to help plants grow at a lower cost than traditional HPS lights.
Many growers use LED lights to help expand plant production because of their full spectrum capabilities, low heat waste and low maintenance, and extended lifespan. Considering that the physiology and morphology of plants are strongly affected by a specific spectrum, LED plant growth lights can effectively promote the growth of crops at a specific time in the growth cycle. With the ability to closely monitor quality, energy output can be easily assessed to expand crop production.
The figure above shows the PAR range-the spectrum of light plants used for photosynthesis. Growth spectra like this include the PAR range and other spectra because it has been found that wavelengths outside the PAR range also contribute to plant growth.
The peak of photosynthetic efficiency (light absorption) falls in the red and blue light spectrum in the PAR range. Red radiation (approximately 700 nanometers) is considered to be the most effective in driving photosynthesis-especially during the flowering stage of biomass growth (important for cannabis growers). Blue light is essential for both the vegetative and flowering stages of plant growth but is mainly used to establish vegetative and structural growth.
The ideal growth spectrum of a plant depends on several factors. These include how specific plants use PAR spectrum light for photosynthesis, and wavelengths outside the 400-700 nanometer range. This kind of light can help speed up flowering, increase nutrition, speed up growth, etc. If the light source is the only (indoor) or supplementary (greenhouse), it will also affect which growth spectrum should be used.
Normally, photosynthetic efficiency occurs at the red and blue peaks, which means that plants absorb the most of these spectra as they grow. You might think that the ideal growth spectrum is equal to sunlight—after all, it has millions of years of experience—however, it is more detailed than that.
Sunlight produces a lot of green, yellow, and orange—they are the easiest spectrum to obtain. Research tells us that although green light is not absorbed by chlorophyll and red and blue (so most plants look green), it is absolutely essential for photosynthesis.
Plants least use the spectrum other than blue and red wavelengths to grow because red and blue are the places where photosynthesis activity occurs most-this is an important reason why full-spectrum grow lights are very effective. After all, growers can become very specific.
Broad-spectrum lighting-usually referred to as full-spectrum lighting, refers to the complete spectrum provided by sunlight. This means that the wavelength of broad-spectrum lighting includes the range of 380nm-740nm (we see it as color) plus invisible wavelengths such as infrared and ultraviolet.
One advantage of LED growth lights is that they can be set to produce specific wavelengths during a specific time period during the day or night. This makes it an ideal choice for plants because growers can separate specific spectral colors based on crops and growing conditions. Full-spectrum lighting can also speed up or slow down the growth rate, promote root development, and improve nutrition and color.
In some crops, blue light is good for nutrient levels and coloration, and a higher ratio of red to far-red light helps leaf size and flowering. This is why today's full-spectrum LEDs are so advanced-because by choosing the right amount of red and blue light, chlorophyll pigments can absorb more of the light they need.
Other indoor growers are also trying to control the use of the far-red spectrum, such as salad leaf growers. Plants associate this spectrum with shadows from direct sunlight, which occurs under the tree canopy, which causes the leaves and stems to stretch when the plant is exposed to sunlight.
This means that when used strategically, larger leaves and blossoms can occur without unnecessary stress. Therefore, although there is no specific LED growth spectrum for any particular plant, the ratio of red light to blue light is very important for maximizing the rate of growth and photosynthesis.
In order to perform photosynthesis and chlorophyll absorbs the maximum amount of light for plant growth, plants use blue and red light most effectively. Other spectra, such as green/yellow/orange, are not very useful for photosynthesis, because the amount of chlorophyll b is mainly absorbed from blue light, while the amount of chlorophyll a is mainly absorbed from red and blue light.
It is worth noting that photosynthesis is more complicated than chlorophyll absorption, but it is important to understand the basic principles.
For growth, blue light is essential to help plants produce healthy stems, increased density, and established roots-all of which occur in the early vegetative growth phase. Then it continues to grow as the absorption of red light increases, resulting in longer stems, increased leaves, and fruit/flowering, etc. It is here that red light plays a leading role in plant maturity and size.
Finally, yield-this boils down to a combination of spectra, which is usually very unique to growers, including growers of multiple varieties of the same crop (such as hemp). No single spectrum can produce more crops-optimal lighting is largely a holistic, constantly changing process.
Certain spectra trigger the growth characteristics of plants. In general, the blue light spectrum promotes nutrient and structural growth, and red light promotes flowering, fruit, leaf growth, and stem elongation. Each crop type is sensitive to different spectra and light amounts at different times throughout the daylight cycle-this directly affects the speed of photosynthesis.
Essentially, we know that controlling the growth spectrum will have a significant impact on the growth area-such as flowering, flavor, color, compactness, etc. However, it is important to realize that specific growth factor signals are part of a larger and more complex cycle. The results also vary depending on the environment (indoor or greenhouse), relative temperature/humidity, crop type, light intensity (lumens per watt), and photoperiod.
UV spectrum ( 100 - 400 nm )
The ultraviolet spectrum that is invisible to the human eye is outside the PAR range ( 100nm-400nm ). Approximately 10% of sunlight is ultraviolet light. Just like humans, plants are also harmed by excessive exposure to ultraviolet light. There are 3 types, UV-A (315-400 nm), UV-B (280-315 nm), and UV-C (100-280 nm).
Although the benefits of ultraviolet light used in gardening are still being researched, ultraviolet light usually brings a deeper purple-in fact, a small amount of ultraviolet light can have a beneficial effect on color, nutritional value, taste, and aroma.
Studies have shown that using controlled amounts of ultraviolet light can also reduce environmental stress, fungi, and pests. Studies have shown that the use of UV-B light ( 280 nanometers to 315 nanometers) can increase the THC (5) and other cannabinoids in cannabis.
Recommend products: CT2 720w UV IR Led Grow Light
Blue light spectrum ( 400 - 500 nm )
The blue light spectrum is widely responsible for improving plant quality-especially in leaf crops. It promotes stomata opening-allowing more carbon dioxide to enter the leaves. Blue light drives the peak absorption of chlorophyll pigments required for photosynthesis.
This is essential for seedlings and seedlings in the vegetative stage, as they will establish a healthy root and stem structure - especially important when stem extension must be reduced.
Greenlight spectrum ( 500 – 600 nm )
Compared with the red or blue spectrum, the green wavelength is less important for plant photosynthesis because it (not) easily absorbs chlorophyll. Nevertheless, green is still absorbed and used for photosynthesis; in fact, only 5-10% is reflected-the rest is absorbed or transmitted to a lower place! This is because green light can penetrate the canopy of plants
In the greenhouse, due to the presence of sunlight, the use of LED grow lights to supplement the green light spectrum is less important than crops that are only grown indoors (such as hemp or vertical crop cultivation).
Red spectrum ( 600 - 700 nm )
As we all know, red light is the most effective spectrum for promoting photosynthesis because it is highly absorbed by chlorophyll pigments. In other words, it is located at the peak of chlorophyll absorption. The wavelength of red light (especially around 660nm ) promotes the growth of stems, leaves, and general vegetative growth-but most commonly, the tall and stretched leaves and flowers.
It must be balanced with blue light to counteract any excessive stretching, such as deformed stem elongation. It is important to consider that although red is the most sensitive spectrum to plants, its efficacy will come into play when combined with other PAR wavelengths.
Far-red light spectrum (700 – 850 nm)
Far-red affects plant growth in several ways-one is to initiate the shade avoidance response. At about 660nm (dark red), plants will feel bright sunlight. From 730 nanometers and above-that is, the ratio of far-red light to a red light is higher, the plant will detect the light "shadow" from another plant or a leaf higher in the canopy, so stem and leaf stretching will occur.
Far-red is very useful for promoting flowering and can increase fruit yield in some plants (6). In short-day plants like cannabis that rely on longer periods of darkness, 730nm can be used at the end of the photoperiod to promote flowering. Many growers are trying to use bursts of red light to interrupt the cycle of darkness to promote growth and flowering.
Find the right grow light
When we understand the way planets interact with different spectra, we need to understand a lot of information and science. We learned that optimized yields and consistent plant quality are due to the use of spectrum together-much like natural sunlight.
We continue to develop our knowledge and research to understand how the spectra of specific crops and strains work best - and what period in the plant's photocycle. Our LED growth lighting system is designed and developed through detailed scientific research, allowing growers to control the use of the ideal spectrum to optimize plant yield, quality and variability.