Carbon Dioxide Basics for Cannabis Production

Carbon Dioxide Basics for Cannabis Production

Professor DeBacco


Cannabis is a C3 plant
C3 plants are most plants such as Tomatoes
Ex. C4 plants include corn and sugar cane
Ex. CAM plants are cacti



CO2 Is Heavier Than Air
Dry Ice to add CO2?
Not advised



Environmental Factors to Consider
Light Intensity
Amount of Carbon dioxide
Temperature



Carbon dioxide
Important input in the photosynthesis equation
All of the carbon that forms the end sugar products originated as a carbon dioxide molecule in the air.



Low [CO2] = Low Growth Rate
Looking at a lettuce study…
Notice the changes in dry mass (yield) at different light intensities across a range of CO2 concentration levels.



Reference Article
Chandra, S., Lata, H., Khan, I. A., & Elsohly, M. A. (2008). Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO 2 conditions. Physiology and Molecular Biology of Plants, 14(4), 299-306.
https://www.researchgate.net/publicat...

Net Photosynthesis in Cannabis Sativa
Optimal temperature for photosynthesis was observed at 30oC.
*Temperature higher than 30 oC had an adverse effect on photosnthesis
At 25 oC, rate of photosynthesis increased with increasing PPFD, but this trend peaked with 1500 μmol m-2s-1 PPFD at 30 oC, and decreased at higher light intensities.



CO2 Levels and Net Photosynthesis
Pn = Net Photosynthesis
WUE = water use efficiency on the leaves of cannabis sativa



Light Levels and Rate of Ps
Notice how at higher light levels plants can better utilize added carbon dioxide.
If adding CO2 make sure the plants are not light limited.
This should be measured with a PAR meter to ensure adding CO2 will be utilized.



CO2 Levels
Concentrations above 5000ppm can be harmful to humans
Called Hypercapnia



Estimation of CO2 Usage
A 32’ x 40’ high tunnel that is (32ft wide x 40ft. long and 12ft at the peak) operating at about 1000ppm of CO2 with the system turning off during venting (period of high heat) uses about 50lbs of CO2 per week.
*This is intended to be a rough estimation.



When Should CO2 Be Added?
In short from emergence to harvest.
However, if this is not possible, then it may be more critical in the early stages to get plants established early.
Seedling phase is a great time because often plants may be slow to get going but the CO2 can help increase root mass.



Autoflowers and CO2
All strains will benefit, but it is highly recommended for autoflowers because there is a set number of days between emergence and harvest.
Growers should be seeking every possible way to maximize each day.
CO2 enrichment allows for higher light intensities to be used which (assuming other factors are not limiting) will result in greater biomass production.
This will translate to higher yields on a plant that only has a set number of days to complete its life cycle.



Will CO2 Increase Plant Production? (Yes, but…)
Yes….. *If*….
No other factors are limiting!
If your plants are receiving optimum light, nutrients, water, aeration, then CO2 can be the boost your plants need.
Keep in-mind that with the addition of CO2 the plants will be able to take advantage of greater light intensity and will likely require more nutrients to meet the increased growth rates.





Link to Lecture Slides: https://drive.google.com/file/d/1JYPC...

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CO2 is Heavier than air
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