When light strikes a material, the resulting light can be divided into three categories: transmission, reflection, and absorption. The amount of light that ends up in each of these categories is determined by the spectrum of the incident light as well as the absorptive properties and transmission spectrum of the material.

The method for determining these spectra is called spectroscopy. This measurement is done by shining a broadband source of collimated light at a material and collecting the reflected and/or transmitted beam. The collected beam is then separated into its constituent wavelengths via grating or prism. A linear array of detectors then measures the intensity of light at each spatially resolved wavelength.

Figure 1: An incident light is shone at a left surface, and the transmitted and reflected light is then separated via a prism and measured with a detector. The absorbed spectrum is inferred from the total amount of light that is not detected.

The result of this spectroscopic experiment tells us the spectral content of the transmitted and reflected beams of light after hitting a leaf. However, thanks to conservation of energy we can also infer the absorption spectra. If we sum the reflectance and transmittance spectra and subtract it from the incident spectra, we are left with the absorption spectra.

The outcome of a spectroscopic experiment is highly material-dependent. For example, even if we limit ourselves to only looking at leaves, the final spectra will be different from species to species and even cultivar to cultivar or strain to strain. See Figure 2 below for examples.

Figure 2: Absorption and reflection spectra of various leaf species. Results were averaged and smoothed from results of measuring 6 leaves per species.

Every atom in a given plant contributes to the absorption, transmission, and reflection profile of said plant. However, the characteristic peaks and dips in a given plant spectra are not attributed to its individual atoms. As atoms bond together to form larger molecules, they behave more like a singular unit than as individual atoms. These coupled molecular systems have a different and larger “bulk” spectral response than the atoms that make them up. In other words, the sum is greater than the whole. This is why we can attribute the features in a plant’s spectra to the organelles (IE chloroplasts) and macromolecules (IE chlorophyll) in the plant instead of the individual atoms in that plant.

Figure 3: The absorption spectra of chlorophyll a and b as well as beta-carotene. The dotted green line shows the typical absorption spectra of a green, leafy plant. The features of the bulk response correlate significantly with the features seen in the chlorophyll spectra. The actual photochemical efficiency is determined experimentally and mathematically.

This bulk response of molecules is why different plants will have different absorption spectra. Even though plants are all made of similar cells and organelles, the relative amounts of these systems in a given plant will affect the resulting spectra. For example, all leaves have cuticles and an epidermal layer (Fig. 4). A leaf with a thicker, more tightly formed cuticle will reflect more incident light than a leaf with a thinner, loosely formed cuticle. Likewise, a plant with a green stem will have more chlorophyll than a plant with a woody stem. A woody stem looks brown because it preferentially reflects red and yellow wavelengths, whereas a green stem reflects green wavelengths of light.

Figure 4: Diagram of the internal structure of a leaf.

Even within a single plant species, we can see different physical and biochemical characteristics of plants. For example, the leaf of a White Poplar (Populus alba) has a dark green top surface and a white bottom surface. This results in a completely different absorption and reflection spectra depending on the direction of the incident light. An example can be seen in Figures 5 & 6.

Figure 5: White poplar leaf

Figure 6: Absorption and reflection spectra of the White Poplar leaf for light incident on upper surface and incident on lower surface.

All of these facts make plant spectroscopy a fascinating and extremely useful tool when examining plants. One could even monitor the health of a plant by monitoring relative changes in its reflection and transmission data. In fact, NASA does uses this knowledge. Healthy plants absorb blue and red light to drive photosynthesis and make chlorophyll. Chlorophyll reflects near-infrared radiation. Since a healthy plant has more chlorophyll than an unhealthy plant, one can monitor the health of the plant by measuring the amount of reflected near-IR light. Satellites orbiting the Earth can collect infrared light reflected off of vegetation on the Earth’s surface and compare it to previously measured data to understand the health of various plant ecosystems.

1. Moss, R. A., and W. E. Loomis. “Absorption Spectra of Leaves. I. The Visible Spectrum.”Plant Physiology, vol. 27, no. 2, Jan. 1952, pp. 370–391., doi:10.1104/pp.27.2.370. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC540339/pdf/plntphys00397-0150.pdf
2. Light Absorption for Photosynthesis, hyperphysics.phy-astr.gsu.edu/hbase/Biology/ligabs.html
3. “Palisade Cell.” Wikipedia, Wikimedia Foundation, 30 Nov. 2017, en.wikipedia.org/wiki/Palisade_cell.
4. “Populus Alba.” Wikipedia, Wikimedia Foundation, 1 Dec. 2017, en.wikipedia.org/wiki/Populus_alba.

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1. Website: http://www.specteros.com/
2. Email: info@specteros.com

Drought has recently become a major concern for some growers. States like Washington, California, and Oregon are seeing major drought issues; water is becoming increasingly scarce and restrictions are getting tighter. With surface water, groundwater, and other water sources drying up, new “water rights regulations” are being put in place; these regulations have increased the cost of water.

Sounds dismal, right? But limited clean water availability doesn’t have to doom you to lower plant yields. You can take a few basic measures that will:

1. Reduce overall water consumption
2. Maintain supplies of clean, usable water for plant growth without significant additions to supply, and
3. Maintain the quality and volume of yields

Lights are, of course, the source of grow room heat. If you keep light usage controlled so that temperatures maintain at ideal levels, plants won’t overheat, become stressed, and give you lower yields. Overheating forces plants to take up more water and then quickly transpire it, which can cause humidity overload when the lights go off. That leads to problems like powdery mildew, it also means that water is used less efficiently than it could be, a major consideration in drought conditions.

Plants need CO2 supplementation during the day to facilitate increased photosynthesis, but not at night. At night, they exhale CO2 and take in oxygen just as humans do. What else do they exhale? Water. As mentioned above, grow room temperatures drop to their lowest at night, which can lead to condensation. That condensation must be removed to prevent mildew and other problems. This is where dehumidifiers enter the picture. Moisture from inside the grow room can be recycled and used again.

Dehumidifiers are essential to maintaining optimal moisture levels in the grow room – and keeping you supplied with a good source of clean, readily accessible water even in drought conditions. Some growers enjoy debating this point, but the issue is settled as far as the science is concerned. With a couple of basic precautions and an occasional quick check with your existing meters, condensate water can be handled just like clean tap water. More on that next time.

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Want to get in touch with Quest Hydro? They can be reached via the following methods:

1. Website: https://questhydro.com/
2. Email: info@questhydro.com
3. Phone: 877-420-1330

A struggle is happening in healthcare research these days and it’s not what you might expect. Over the past 50 or so years, the medical industry has shunned many natural compounds. Research scientists have been struggling to gain recognition for their work surrounding natural organic compounds such as terpenes and flavonoids. If you ask me, it’s a breath of fresh air (literally) after years of personal dedication to the power of plants. I find the change in attitude almost silly, but we’ll leave it up to the experts.

Much of the pleasure derived from cannabis is owed to what’s called the terpene synthase family. Many are quick to cast aside terpenes as purely aesthetic. After all, like many organic compounds found in nature, they have been used by mankind for things like perfumes. but when you really consider it you see that terpenes were in every aspect of early humans’ lives. But terpenes were used for more than just frilly things:

1. Terpenes in certain plants could be used to deter scavengers and predators.
2. Terpenes can dull food taste better, keep longer, and ease certain health conditions too.
3. Terpenes can mask unpleasant scents.

Today, the value of terpenes can be found in the growing popularity of cannabinoid therapy. In cannabis, we can see the brilliance of nature. There are 127 identified terpenes, many of which are responsible for solutions to illness and its symptoms. However, cannabinoids seem to get most of the credit for these medicinal benefits. In fact, Canada’s legal program only requires cultivators to quantify the THC and CBD in each strain, regardless of terpene content.

You can imagine my excitement when I heard about Dr. Dedi Meiri and researchers from Technion, Israel Institute of Technology. Dr. Meiri holds a B.Sc in Biochemistry and a PhD in Plant biotechnology, making him uniquely qualified to investigate the therapeutic potential of phytocannabinoids. Not only are they involved in eight clinical trials but they’re also creating an integrated confidential database to study each strain and its chemical compounds in relation to different ailments. The “Cannabis Database Project” will help future patients and healthcare professionals to effectively recommend strains based on this evidence. His laboratory may be the only one in the world that can identify each and every chemical compound in Cannabis that contributes to the “entourage effect” proposed by Dr. Sanjay Gupta. I recently had the chance to watch Dr. Meiri speak at United In Compassion’s Cannabis Symposium. I urge you to watch the video, but if you don’t have time, I have included a set of quick answers below.

I for one will be keeping my eyes on Dr. Meiri and his team. In researching this piece I emailed one of their team members to see how the studies were going and received a reply the next day. Hopefully we’ll see lots of data coming out of it.

Yes! You can find the answer approximately 26 minutes in.

Cannabinoids treat cancer by causing cell death, a process called Apoptosis. This is a process that all healthy cells have the ability to do in times when they are unneeded or are sick, but cancer cells don’t use this built-in off-switch. Certain cannabinoids force them to do what they should instinctively do, self-destruct. Along the bottom are 12 different extracts made from 12 different Cannabis strains and as you can see, some kill these particular cancer cells better than others.

No! You’ll find the response approximately 27 minutes in.

Just look at all of these organic chemical compounds! There’s almost no doubt in my mind that they have a purpose and it may be necessary to measure more than just those two main cannabinoids.

Yes! The response is approximately 28:50 minutes in.

As you can see here, the C02 extraction method performs so much better than the Ethanol extraction method. This expands the number of questions I have! Is it because C02 pulls more cannabinoids than the Ethanol?

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Want to get in touch with Boveda? They can be reached via the following methods:

1. Website: https://bovedainc.com/
2. Email: dan.cleveland@bovedainc.com