HorticultureSpectrum

Basic Knowledge of LED Grow Lighting

What is light?
Light is an electromagnetic wave. This wave contains a wavelength which will be measured in meters, nanometers to be precise. Mathematically speaking that’s 0.000000001. this can be abbreviated by exploitation nm. White light could be a mixture of all wavelengths of light. The hue or color that a light provides off is owing to the number of light from a curtain wavelength. Below 400nm is termed ultra-violet or ultraviolet illumination. on top of 700nm is infrared or IR lighting. The wavelength of every color is as follows: (note that as colours meet up with to every alternative the hues mix together)
  • UV C: 100-280nm
  • UV B: 280-315nm
  • UV A: 315-400nm
  • Violet: 380-450nm
  • Blue: 450-495nm
  • Green: 495-570nm
  • Yellow: 570-590nm
  • Orange: 590-620nm
  • Red: 620-750nm
  • IR A: 700-1400nm (near infrared)
  • IR B: 1400-3000nm (mid infrared)
  • IR C: 3000nm-1mm (far infrared)
The human eye sees light from ~400nm to ~700nm. There are an oversized variety of measurements utilized in lighting and optics. i’m progressing to cowl the common ones during this thread. If you’d prefer to see a lot of click here.

Lumens

This is directly from Wikipedia, as they explain it all right.
“ The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total “amount” of visible light emitted by a supply. radiant flux differs from power (radiant flux) in this luminous flux measurements mirror the variable sensitivity of the human eye to totally different wavelengths of sunshine, whereas flux measurements indicate the whole power of all light emitted, freelance of the eye’s ability to understand it. A lux is one lumen per square meter. “
Lumens area unit skew toward what the human eye sees higher. Therefore, lights that contain a high amount of greens and yellows have the next worth given to them than those that contain less or no green and yellow. this can be an okay measure to use once comparing two bulbs/panels of the precise same lighting sort or wavelengths, however terribly poor once comparison light sources of various varieties. For example: once comparison 2 HPS bulbs (with roughly identical spectral output) the one with the upper lumens are going to be a brighter bulb. However, if you’re making an attempt to match two CFL bulbs one that’s cool white and one that’s heat white, the nice and cozy white can have roughly five a lot of lumens per watt.
Photosynthetically active radiation
Photosynthetically active radiation or PAR could be a measurement of all light between 400 and 700nm. this can be wavelengths of light that management MOST chemical process. in contrast to lumens, PAR doesn’t skew the results of the photon count toward any given color and is expressed in µmol photons/ m2/second. It merely records the amount of photons of the wavelength(s) being measured. you’ll additionally see the term PPFD or photosynthetic photon flux density expressed as W/m2. this can be the measure that’s most valuableeful|most respected|Most worthy} to us as plant growers.
Radiant Flux
“Radiant flux or radiant power is that the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light). the ability could also be the whole emitted from a supply, or the whole landing on a selected surface.” Again, Wikipedia contains a nice definition. this can be largely utilized in technical publications and development, however is that the most correct measure which will tend. it might be nice to use this measure for growing but you’re unlikely to examine it on any packaging.
Chlorophyll and light absorption.
Chlorophyll is that the main a part of photosynthesis. this can be why leaves area unit green once light by white light. chlorophyll could be a inexperienced pigment that is found all told plants. However, there’s quite one sort of chlorophyll. There area unit a minimum of six well-known varieties of chlorophyll and possibly a lot of (the last chlorophyll to be discovered was in 2010). We tend to all recognize that chlorophyl is what makes plants grow and that they absorb the sun/light to create that happen. many of us aren’t awake to all of the opposite photoreceptors (light catchers) in plants. There area unit between two hundred and 300 photoreceptors in each plant. Some botanists believe that there area unit still a whole lot if not thousands to be discovered. These antenna or accent pigments play a far larger role than most of the people assume. The reactions that occur inside a plant area unit terribly complicated. light hits the leaf, excites a photoreceptor pigment that then performs a chemical reaction that’s passed on to subsequent. As PS1 loses and negatron it gains one from PS2, this can be referred to as hill reaction. This method happens in chlorophyll, move through carotenoid, zeaxanthin, carotene, lycopene, and so to chlorophyll. this can be only for the assembly of sugars that the plant uses to grow. after we quote cannabis or alternative higher plants there area unit variety of alternative reactions that occur for the building of cannabinoids and alternative compounds used inside the plant. Below area unit a number of the wavelengths for plant photoreceptors. (Note that almost all photoreceptors have multiple peak absorption points.)
  • Chlorophyll A: 430, 662
  • Chlorophyll B: 453, 642
  • Alpha Carotene: 442, 444, 478
  • Beta Carotene: 425, 480
  • Zeaxanthin: 423, 451, 483
  • Lutein: 420, 447, 477
If you compare that list with the above list of wavelengths, you may see that none of those photoreceptors are in the green or yellow region. this can be another example of however the lumen measure doesn’t equate to the expansion of plants. Or find more knowledge of Spectrum
Emerson Impact
This leads ME to the Emerson impact or Emerson enhancement effect. This has been utilized in virtually every plant photoreceptor study since he revealed his 1st paper on that in 1957. once illuminating plants with 700nm wavelength red light, he noticed  that photosynthesis was slowed greatly. identical occurred once light with 650nm red light solely. However, the mix of the 2 generated a dependent response and increased  the expansion rate to double that of the only sources combined (a fourfold over every light alone). His later work indicated that there wasn’t one however 2 photosynthesis traps. we tend to currently decision these PS1 and PS2, wherever every system transfers energy and electrons to every other increasing productivity.