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Cannabis Selective Light Training (SLT Training)

Cannabis selective light training

Table of Contents

Selective Light Training (SLT) involves striking certain areas of a plant with light to manipulate proteins. A standard plant will contain over 1,000. Blue light is used to control the phot1 and phot2 Phototropin proteins. Blue causes cannabis plant cells to not elongate (as much), resulting in a more compact plant when hit with blue. Plant cells, such as those found in leaves, may rapidly expand in the absence of blue light. The issue is that a minus blue only light source may cause significant stem elongation, and some plants, such as sweet basil, may not grow at all. You get the best of both worlds with selective light training in a low-cost mass-production product.

Selective Light Training can be utilized with any type of light source, such as genetically modified organism research, protein research, bonsai trees (maybe even cannabis bonsai), and industrial-scale agriculture for early-stage plant growth, such as apple, citrus, coffee and tea tree nurseries. SLT only needs to be administered in the early stages of a plant’s life to reap the benefits of early-stage stem elongation reduction on an industrial scale. Additionally, the Selective Light Training is not intended for novice growers but rather for intermediate to expert growers who want to master cutting-edge growing technologies and like getting their hands dirty with some experimenting.

How to make SLT work for you

To use on cannabis stems, position the blue LED array close to the stem and provide continuous light. That is why 2055-degree oval LEDs are recommended. The 20-degree side-to-side aiming slop and the 55-degree vertical provide little overlap. By connecting three in series with a 330-ohm resistor and constructing a linear array, you may use an unregulated 12-volt power source. All of this is done to reduce expenses. According to experts, no one has ever seen one of these blue LEDs burn out at a lower power level. A close-up of the light sticks is shown on the left, and an even closer view of the epoxy encapsulation is shown below. These light sticks are easy to make (for personal use only, legal of course). Other wavelengths of light can be employed on different areas of the plant, with blue light blasting only the stem.

Plant reactions to SLT

Not all cannabis plants react the same way, and the findings appear to be strain-dependent (sweet basil, lettuce leaf basil, and purple basil respond differently). As a result of selective light training, the Mystery Skunk cannabis plant produces 4-5 internodes per inch. A Mystery Skunk plant will provide 4-5 internodes per inch, even at reduced primary lighting levels. Excess stem elongation is no longer an issue, and you can expect substantially higher growth per area or volume. Use light sticks solely for veg development and the first two weeks of flowering on short-day plants.

SLT training cannabis

For example, consider a Purple Arrow strain that has undergone selective illumination training (this is a low-yielding strain). This plant was not topped and demonstrated how various strains could produce morphological variances. The blue light on the stem produces narrower plants, but you must test the strain to see how well SLT works for that strain. Again, intracanopy illumination allows for more plants per area and higher production. Intracanopy sunlight frequently necessitates foliar nitrogen feeding and will result in a higher heat load and increased humidity due to the enhanced photosynthesis rate. You cannot accomplish this only through the use of blue side illumination. Blue side lighting blocks light from reaching the stem, causing the leaves to grow downwards. You must deliver the blue light near to the stem, which distinguishes side lighting, intracanopy lighting, and selective light training.

Intracanopy lighting

According to the pressure-flow concept, the sugars produced by the lower leaves through photosynthesis from reduced illumination are transferred through the phloem to where there is a lot of new growth (sink), cannabis flowers in this example. Because of the cellular respiration required to keep leaves alive, they become a sugar sink rather than a sugar supply if they fall below their compensation threshold. Use intracanopy illumination to get higher yields per square foot than would otherwise be achievable. Use SLT to increase intracanopy illumination efficiency by bringing the lower leaves closer together.

Light spectrum

Cannabis plants may use green light, and green is more photosynthetically efficient at greater illumination levels than red. This is due to the saturation of the top layer of chloroplasts holding chlorophyll, allowing green to penetrate deeper into leaf tissue (sieve effect) and be reflected around until absorbed by another chloroplast containing chlorophyll (detour effect). The fluorescence of chlorophyll can be used to evaluate this efficiency. When utilized alone, green light causes a lot of elongation. HPS grow lights emit an abundance of green, yellow or amber light. Because the two primary protein groups involved in photoperiodism control, cryptochrome and phytochrome proteins, are generally unresponsive to green light, you can utilize a green LED “safe light.” This has absolutely nothing to do with photosynthesis. Many additional proteins are involved in photoperiodism and blooming.

Why should you use a blue light?

In most skilled cultivators’ experience, the bottom underside blue light on the stem helps most plants stay compact. It is resisting the effects of gravitropism, or a plant’s inclination to grow upwards. The same hormone, auxin, controls both of these phenomena (gravity and blue light impacts).

Utilizing a cheap lux meter as a plant light meter

To evaluate the light intensity, you should use a light meter. Light intensity has a significant impact on photosynthetic rates. The rate of photosynthesis is the most important factor influencing your harvests. To a certain extent, greater light equals more yield. A light meter just determines the amount of light, not the spectrum. This is close to the values we desire with an inexpensive lux light meter at the top of the plant canopy level for everything except LED grow lights:

Using a lux meter to analyze light requirements

  • 15000-20000 lux: this is the lower end of what you desire for vegetation growth.
  • You want to aim for 35000-40000 lux for blooming.
  • 75000 lux or so: Going above this degree of light intensity and saturation is unnecessary.

This information is used to establish how far away the light source should be from the cannabis plant. You should not just aim to bring the plant as near the light as possible without burning it. There are much too many different types of lighting, as well as far too many other factors, to apply that as a general guideline. For instance, blowing air on the light and cannabis plant will allow us to bring the plant closer to the light without burning it, but we may exceed the 75000 lux limit in the process. Because you’re now overloading the plant, that’s just a waste of energy. Choose the 35000-40000 lux level for the greatest yields per lighting level. You do not utilize this information to decide the type of light you use.

If in doubt, consider 75 as a near enough conversion figure. This implies that for veg development with a white light source, you should aim for at least 15000-20000 lux (approximately 200-250uMol). For blooming, you should aim for 35000-40000 lux (about 500uMol), and they do not exceed the line for blooming is suitable for around 75000 lux (about 1000uMol which is the photosynthesis saturation point).

Note: It is usually ideal to use a light meter with the sensor or meter facing straight up rather than directly at the light source. This is compensated for by the light meter’s little white semi-sphere or flat piece of plastic. The lesson here is that a lux meter is precise enough to provide significant data with white illumination.

The dos and don’ts when using SLT

A lux meter cannot be used with LED grow lights, although you may use it with white LEDs. The conversion factor is just incorrect. A red 647 nm LED, for example, had a conversion ratio of 10.3 when tested with my own spectrometer, but a red 620nm LED had a conversion factor of 44. A blue 462nm LED weighed about 12.8 grams. When comparing two distinct light sources in a grow comparison, the lighting intensity must be the same.

Why?

  1. First, photosynthesis is not linear unless between around 50-500 uMol. LEDs frequently used in grow lights provide dramatically different readings than white lights such as HPS.
  2. Second, several plant proteins are expressed at varying illumination levels, which may and will influence plant growth.
  3. Third, chloroplasts can migrate to the sidewalls at increasing blue light intensity, reducing plant photosynthesis efficiency. This is known as cytoplasmic streaming, and it is used for photoprotection.

Here are some instances of light as measured in power by spectrum and how human eyes and a lux meter experience it; a genuine spectrum of a 2700K CFL and how a lux meter reads it. The red or green (middle and right spike) ratio will shift dramatically. This is because your eyes and lux meters are far more sensitive to green light. Why are quantum light meters so exorbitantly priced? Scale economies and increased precision The cheapest quantum light meter capable of providing accurate readings with LED lights is $800.

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Taylor Christianson
Taylor Christianson
Taylor is an indoor expert. Through their writing, they offer a masterclass on growing cannabis indoors, maintaining a productive growing environment, and guiding growers through all the stages of growth both indoors and outdoors. Combining multiple fields of expertise allows for Taylor to give in-depth insights into cannabis growing overall. If you want to know about different lighting, temperatures, and humidity for different stages of growth then Taylor can offer you this knowledge. Taylor has mainly worked in the background of the cannabis industry for many years, they have provided articles for numerous publications and had their work published in print dozens of times during the late golden years of print media. Taylor’s approach is continuously innovative and it’s always exciting to see where they’re going to go next and how far they can push the development of cannabis cultivation one article at a time.
Taylor Christianson
Taylor Christianson
Taylor is an indoor expert. Through their writing, they offer a masterclass on growing cannabis indoors, maintaining a productive growing environment, and guiding growers through all the stages of growth both indoors and outdoors. Combining multiple fields of expertise allows for Taylor to give in-depth insights into cannabis growing overall. If you want to know about different lighting, temperatures, and humidity for different stages of growth then Taylor can offer you this knowledge. Taylor has mainly worked in the background of the cannabis industry for many years, they have provided articles for numerous publications and had their work published in print dozens of times during the late golden years of print media. Taylor’s approach is continuously innovative and it’s always exciting to see where they’re going to go next and how far they can push the development of cannabis cultivation one article at a time.

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