[Beta Test Team]

We'll use this thread to post graphs of the RQEs (relative quantum efficiencies) of Cannabis for various action spectra (plant responses to radiation spectrum) listed here:
https://www.icmag.com/ic/showthread.php?t=295933

All of these RQEs are approximate because they're made by using action spectra from other species weighted with Cannabis absorptance spectrum (as a mean of all growth phases for drug biotype Cannabis). And interspecies action spectra are not identical, meaning Cannabis will have slightly different response to radiation (light) spectrum vs. the species we used to create these RQEs. Here is the mean Cannabis absorptance spectrum we made we're using for the RQEs:
https://www.icmag.com/ic/showthread.php?t=293045

Assuming +/-2.5% to +/- 10% error margins for all the approximate RQE of Cannabis ("aRQEc") we will post is probably safe. In 2015 we hope to start creating action spectra using Cannabis, to create accurate RQEs for Cannabis. For now though, these are probably the best option there is currently.

Each post in this thread will have a different RQE graphed. Over the holiday I'll try to get other graphs posted to this thread.

Briefly, these graphs are made by dividing action spectrum (commonly used in published literature) by mean Cannabis absorptance spectrum to create the quantum yield (efficiency) for that action spectrum, which is then normalized to 1 to create relative quantum efficiency (RQE).

Here are good reviews and info of the science behind these graphs:
https://plantsinaction.science.uq.edu...ght-absorption
https://plantsinaction.science.uq.edu...action-spectra
https://www.photobiology.info/Gorton.html

[Beta Test Team]

So to start off the thread here's the approximate RQE for Cannabis photosynthesis for growth chamber and field conditions. This graph represents the response during vegetative and flowering growth, because there isn't a lot of difference in Cannabis leaf absorptance for 'veg' and 'flowering.'

You'll notice some big differences between indoor (growth chamber) and outdoor (field) RQE Cannabis photosynthesis, those include:

a) The waveband range of about 500 to 600 nm. The cause of the difference is due mostly to the reduction in growth chamber leaf absorptance from the work of Keith McCree (1972a), where at 550 nm it's about 67%, while field grown leaf absorptance at 550 nm is about 76%. And the mean Cannabis field grown leaf absorptance at 550 nm is about 76%.

b) The beginning and ending of the graph was smoothed, using Gaussian smoothing and a little manual smoothing. The beginning and ending wavebands (about 300 to 375 nm and 750 to 800 nm) are likely around +/- 2.5% to +/- 20% inaccurate. In later versions I will better smooth the waveband range of 750 to 800 nm.

Here are good reviews with info and study:
(webinar) https://www.licor.com/env/webinars/we...10.html?form=1
https://www.photobiology.info/Brennan.htm
https://elibrary.asabe.org/abstract.asp?aid=30952

[Beta Test Team]

Here's one lots of people may like: UV-B and UV-A biological spectral weighting functions (BSWF) to create RQE for Cannabis:

These data are based upon an improved version of the data (weighting functions) used by researchers studying UV-B effects on THC and CBD, for example, the well known study by Lydon, Teramura, and Coffman (1987), where they report the radiation by "UVBbe" (i.e. UV-B adjusted with the correct BSWF):
https://onlinelibrary.wiley.com/doi/1...757.x/abstract

These data, like all RQEs, are used to weight the radiation measurement (for example, PPF) to reflect how the spectrum effects Cannabis for the given response (in this case, response to UV radiation). So when researchers study effect of UV-B on Cannabis, they measure the UV-B irradiance, and then adjust that measurement with those data (weighting functions), to find the amount of 'effective' radiation the plants get, instead of the total UV-B the plants get.

What we did is take the BSWF for UV plant growth inhibition one step further and adjusted it with Cannabis absorptance, to create the aRQEc presented below. However, the Cannabis absorptance for UV-B and narrow UV-A wavebands may be inaccurate by +/- 2.5% to greater than 10%, so the resulting UV-Bbe and UV-Abe measurements need to be seen in that light.

We are going to carry out research studies on UV-B and UV-A effect on THC and CBD in the coming year, so calculating these data was the first required step. And these data (found in this spreadsheet*) can be used by anyone who uses UV-B to correctly measure irradiance (though you'll need to first analyze your radiation source's SPD).

Please ask if something isn't clear. We hope these data for UV-B will be useful to growers, and growers will start reporting UV-B irradiance as UV-Bbe weighted with our aRQEc of UV growth inhibition, or using Flint and Caldwell's BSWF (action spectrum) that is also included in the spreadsheet.

* https://www.icmag.com/ic/showthread.php?t=295933

Here are good reviews with info:
https://plantsinaction.science.uq.edu...-plant-biology
https://www.photobiology.info/UVphoto.html
https://www.photobiology.info/Jenkins.html
https://www.photobiology.info/Jagger.html

[Beta Test Team]

Here's another one lots of people may like and make use of, at least we will:

This is the response (approx.) to blue light (from UV-A to 500 nm) for Cannabis in terms of things like phototropism (growing toward radiation source), stomatal opening (also see this thread*), chloroplast movement, photonastic responses, etc. - in the end, severing to optimize photosynthetic efficiency.

This helps to show why Cannabis responds well to MH, and a combination of MH/HPS. Work by Dr. Bugbee, and others, have found around 8% to 10% of total PPF as blue light range (400-500 nm) is adequate for supplementing common HPS spectra; but we have found for Cannabis around (and greater than) 15% is better (personal testing).

* https://www.icmag.com/ic/showthread.php?t=295194

Here are good reviews and info:
https://plantsinaction.science.uq.edu...-and-responses
https://plantsinaction.science.uq.edu...3-phototropism
https://www.photobiology.info/Christie.html
https://www.photobiology.info/Franklin-NLE.html
https://www.photobiology.info/Shinkle.html
https://www.csulb.edu/~cwallis/170/te...tropins.02.pdf
https://www.mcdb.ucla.edu/Research/L...ience-STKE.pdf
https://www.plantcell.org/content/13/5/993.full

[Beta Test Team]

Another good one, this time specific to stomatal opening as effected by UV-A to cyan spectrum range. These source data (using wheat seedlings), like the other source data for the graphs above, are commonly used throughout the published research literature:

This is pretty self-explanatory, however, note the similarities between this graph and the one above, for phototropin mediated responses. Also, here's a thread where I posted some other graphs and info relevant to this post (like about green light effects):
https://www.icmag.com/ic/showthread.php?t=295194

Here is good reviews and info:
https://plantsinaction.science.uq.edu...tal-physiology
https://plantsinaction.science.uq.edu...matal-aperture
www.plantphysiology.org/content/119/3/809.full

[Beta Test Team]

Here's the opposite of the graph above, basically. In simple terms, this graph shows how green to yellow wavelength ranges close stomatal (reduce aperture size):

This graph depicts how radiation (generally, yet inaccurately, termed 'green light') reverses the stomatal opening from 'blue light' (again, that term is inaccurate, it's really UV-A to cyan).

Something I wrote in a different thread:

Stomatal opening as a function of spectrum is affected by ultraviolet, blue, green and red wavelengths.

In the case of green that's the reversal of blue light stomatal opening, so green light reduces (narrows) stomatal apertures after blue light increases (widens) stomatal apertures.

Blue light has by far the strongest effect on stomatal opening, it takes a lot more red light to have the same effect as blue light (somewhere around 10x the amount if I recall correctly).

In terms of blue light photoreceptors and effect on stomatal apertures, using the generalized phototropin action spectrum is likely a good route. However, there are specific blue spectrum action spectra for some plants that are used as a generalized action spectrum for stomatal opening.

For full reversal of blue light mediated stomatal opening when there's blue and green light present, by green light, it takes about a 1:2 ratio of blue:green photon flux (if I recall correctly, I have to check my notes).

Here are good reviews and studies with info:
https://5e.plantphys.net/article.php?id=267
https://www.amjbot.org/content/89/2/366.full
https://pcp.oxfordjournals.org/content/41/2/171.full.pdf

[Beta Test Team]

This one is pretty neat, showing damage to photosystem II (PSII) by wavelength:

PSII 'damage' means photoinhibition, which isn't good for plant growth or photosynthetic rate, among other things.

This shows green/yellow light has greater PSII damage than most of blue and red ranges, with UV having the greatest PSII damage (sharp spike at narrower blue range). The spectrum was normalized to 1 at 400 nm (thus the obvious increase), but in reality the UV-A and UV-B waveband ranges have far greater relative PSII damage than PAR range.

What I find interesting is how this graph (based on a mean of two separate PSII photodamage action spectra) mirrors what other researchers have found in terms of green/yellow light reducing plant growth and causing issues including photoinhibition and increase in photorespiration.

Here are good reviews and studies for info:
https://jxb.oxfordjournals.org/content/58/12/3099.full
https://cpl.usu.edu/files/publication...b__4116525.pdf
https://www.amjbot.org/content/100/1/70.full
https://www.doria.fi/bitstream/handl...pdf?sequence=1
https://www.plantphysiol.org/content/153/3/988.full
https://pcp.oxfordjournals.org/content/47/3/391.full
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2955740/

[Beta Test Team]

Okay, no more aRQEc graphs for a little while. We still have to create 4 or 5 more, but we haven't yet created the data for the graphs.

[Feijao]

Thanks so much for all the info! Broncos's game and researching approximate RQE of Cannabis all day for me.

[Beta Test Team]

I'm glad you like them. Please ask anything that isn't clear, of if you see issues or have suggestions.

Here are the options we're considering for the next round of action spectra we're using to create other new aRQEc. Though these may not be done until next month, and some may be not accurate enough to use (like UV stomatal opening):

Cryptochrome 1 (growth inhibition, e.g. reduces stretch)
Cryptochrome 2 (degradation)
Photoreactivation (regarding UV-B photodamage)
DNA photolyases for photorepair of cyclobutane pyrimidine dimers (regarding UV-B photodamage)
Flavinoid biosynthesis
Red light stomatal opening
UV light stomatal opening