Old technique, new application in cannabis

Back in our high school biology or in a first year botany class you may have done this very practical experiment with spinach leaves.

Isolation of Chlorophyll from Spinach

If you substitute the cultivar you want to know more about the amount of pigments present.

Why would I want to know what pigments are present in my favorite plants? Well the spectrums you want for LED lighting.

Light that is absorbed by the plant is totally based on pigmentation. We know the absorption of light based on the form of chlorophyll. The ratio of chlorophyll a and chlorophyll b. The absorption spectrum is different for for the two forms of chlorophyll, and well documented. This is where PAR comes from, but is only part of the story.

What is not well documented for cannabis is the absorption of your secondary pigments. But, these secondary pigments are know to be key in the production of secondary plant compounds. And why we want to grow cannabis is the secondary plant compounds, THC and CBD.

Secondary plant pigments are generally the starting point for for secondary plant compounds. You excite the pigments with light just like we excite chlorophyll, with light.

If we know the absorption spectrum of the secondary pigments we should see more secondary plant compounds. (Reference needed here, Look at Erthroxylum coca and Glycine max).

I would start by picking the cultivar you like best. Pick a really fine looking plant, you need one of your best, that is in flower. You only need the leaves.

Use the extraction method I sited above.

Additional equipment needed
A high quality Pyrex flask beaker in the 1000 milliliter size. This beaker is flat on two parallel sides. I like the purists silica glass I can find. They have an absorption spectrum of there own and is documented.

With a really fine quality light and a good spectrometer. Do the following.
See what the light spectrum is of your light.
See what the light spectrum of light is through the empty flask beaker.
See what the light spectrum of the the extraction liquid is prior to extraction.

Now fill the flask with your extraction. Take your your spectrum readings from both the light passing through and light reflecting from the front. The front measurement is harder. To help with the front collection, I use a good quality 10x broad lens to help capture the light for the spectrometer.

The light passing through shows what light is not used by the plant. Light reflecting from the front shows what is not being absorbed but reflected.

With these two pieces of information you can determine the exact spectrum your plants need for optimal growth.

It not just total PAR we care about. We want to know what the total absorption spectrum of the secondary pigments.

Now you know why I want tunable spectrums from my light source and why LED lights are my dream come true.

I have done this very experiment on a lot of floriculture crops. Most particularly in Latherus oderatera cultivars (sweet pea).

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One more thing you can do with the extract is chomogrophy. You put a drop of solution on the bottom of a strip of chronograph paper. Let it dry place the end of the paper in ascitone and the pigments will separate by weight up the paper.

Using a standard botany book you can determine the types of pigmentations present by where they end up on the strip.

@Hunter you will have fun with this.

@GrowFlux, @LED_Cultivation, take a look at the primary post. I would be interested in your thought?

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Firstly, I don’t have the formal education required to properly understand this. However, members of our team absolutely do, and I will be forwarding this information to them.

This is precisely the type of depth we’re pursuing. I will see what everyone else has to say about this, as again, I’m simply not qualified.

“It not just total PAR we care about. We want to know what the total absorption spectrum of the secondary pigments.”

I whole-heartedly agree. We are taking absorption spectrum, photochemical efficiency, etc. - Into consideration regarding the article we’re working on. This definitely provides a better understanding in terms of how in-depth the subject at hand is, and the types of things one could do to help further the optimization of our spectral configurations, etc.

I will of-course be taking a more in-depth look at this content. But the real wisdom will come from the team. I’m merely a messenger in this situation.

Thank-you for taking the time to share. Very cool stuff.

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One interaction of spectrum and chlorophyll absorption is that the topmost layer of leaves and cells in a leaf will absorb these colors first.

This means red and blue (common narrowband LED colors) get trapped at the top of the canopy, whereas other colors (yellow, green, IR) pass through.

Food for thought :slight_smile:

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I know from doing this experiment more than once “granted” on spinach. That the light that passes through the flask, and then through a prism to split the visible spectrum gives some vary intriguing results. As does the splitting of the reflected light from the front. The cost of doing this experiment is under a $100. I used to do the prep work for my mothers biology high school class every year for more than 10 years. I would do the prep work in our family kitchen. Only takes about 1.5 hours prep work and the solution is good 5 days.

I had to use this demonstration with FFA horticulture students visiting the university as a graduate. They used me because I had done it more than anyone else on the team.

I think it would be a perfect sales tool for light manufacturers. Growers are vary touchy feely learners as a group.

The only trick is setting up the mirror for focusing the reflected light, from the front. I learned to barrow a lens from my father the eye surgeon, portable eye testing kit.

The reflected light is as interesting as The absorbed light.

Plus, you can identify execactly the pigments and there relitive ratios to one another. You can show the different molecular weight of each pigment and there effect on light.

Also the solution makes carbohydrates when light is turned on so you can show parts of the creb cycle.

Just more food for thought, I think using cannabis as the plant material would sell the lights themselves.

My dream after doing this experiment was the ability to tune my future greenhouse lights. I would have to look at our inventory for build cost in 1990 but I bet my HID lights cost about half of my greenhouse structure frame cost. And we used Nexus greenhouses with 12 foot sidewalls. Today lighting is such a lower investment cost and negligible on operating expenses. I bet my fans electric usage would be higher than my, electric bill than LED lights. This was certainly not true with HID lights. I would cringe every time we needed supplemental lighting. The meter would spin so much faster with the HID lights on.

This is one reason I want to know my cost accounting down to the gnats ass. I want to pay my workers not my utility company. Employee are your biggest cost and my biggest asset. Training a good junior grower cost about a years wages before they are truly engrained in your production techniques and can show a return on the investment.

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Additional methods for pigment extraction. I would shoot for scaling up for a liter at a time.

The first paper is the why this is a really useful method.

Paper from 1940

The method I use from Carolina Biological. Fun and may be best for cannabis demonstrations :heart_eyes: @Growernick this makes a show stopper display for a lecture on growing. It shows why we care about light and pigments. It is highly dramatic. You get lots of gasps.

https://users.stlcc.edu/mhauser/Col%20Chrom.pdf

http://www.chem.ucla.edu/~bacher/CHEM14CL/Handouts/Spinach_Pigments%20handout_Spring%202016.pdf

https://www.hamline.edu/WorkArea/DownloadAsset.aspx?id=4295023241

There are many other methods.

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The problem is more complex. Only some of the leaves are doing 90% of the work. The leaves closest to the axial branch buds do most of the heavy lifting. Lighting anything else is not practical from a cost benefit ratio. There is a good paper from ww2 looking at photosynthesis in hemp. I will try to remember to post the link. @Hunter did I forward a paper to you on “photosynthetic properties of hemp in carbohydrates synthesis”? I have a note I have the paper, but I can’t find it.

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