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How much CO2 do your cannabis plants need?

“One of the most defining events in the history of Earth is the emergence of photosynthetic organisms.”



How much CO2 do your cannabis plants need?
Home » News » Production » How much CO2 do your cannabis plants need?

In this article, Gary Yates, chief scientific officer at PharmaSeeds, discusses optimum levels of CO2 for the best cannabis yield. 

Photosynthesis is the process by which light energy is used to catalyse the oxidation of water, essentially splitting water molecules and producing hydrogen ions, oxygen and electrons. These products are transferred through intermediators to produce organic carbon compounds, mostly carbohydrates (sugars), in a process called carbon fixation (Blankenship 2014). 

This is a very basic summary of a complex process that involves many enzymes and complexes through both the light-dependant and dark reactions centres to produce energy which is stored as sugars (Whitmarsh 1999, Buchanan 2016).

One of the most defining events in the history of Earth is the emergence of photosynthetic organisms. This started a cascade which ultimately changed the composition of the air, renewed the natural fauna and ramped up production of the highly reactive and toxic element oxygen. When these organisms first evolved, the ratio of CO2 to oxygen was vastly different and is almost completely opposite to what we see on Earth today (Beerling 2012).

This is important because in a CO2 rich atmosphere, the chemistry which enables photosynthesis did not have to be highly specific to bind CO2. However, as the composition of the atmosphere changed due to continual uptake of carbon dioxide and production of oxygen from photosynthetic organisms, it affected the efficiency of the process (Lowe and Tice 2004).


Nowadays, photosynthesis (particularly in C3 plants such as cannabis) is not as efficient a process as one may assume. The central catalytic enzyme for carbon fixation, rubisco, is well known for its promiscuity, and in many species rubisco binds oxygen at roughly the same efficiency as carbon dioxide, leading to photorespiration – an energetically negative pathway. However, optimising rubisco by increasing the availability to inorganic carbon has been modelled in crops and is predicted to increase yields by up to 60 per cent (Long et al., 2016).

In some cases, simply elevating the ambient CO2 levels can increase yields by 30 per cent (Poorter 1993, Kimball 1983). This clearly demonstrates that the photosynthetic process at current ambient CO2 Levels is less effective than it could otherwise be, probably a result of the difference in CO2 levels now compared to when photosynthesis first evolved where atmospheric CO2 could have been as high as 10 per cent, currently 0.04 per cent (400ppm) (Lowe and Tice 2004).

Read more from PharmaSeeds: Improving cannabis yield 

At maximum efficiency 90 per cent of a plants dry biomass is derived from photosynthetic CO2 capture, thus there is a very tight correlation between the yield of a crop and the sequestration of CO2 (Zelitch 1975, Zelitch 1982). This is evident throughout a plant’s life cycle and the effects of elevated CO2 can be seen from the seedlings through to the mature plant, in both temporary short term and consistent long-term exposure to elevated CO2 (Kimball 1983).

Elevating levels of CO2 will encourage extra growth only when other limiting factors are abundant. Therefore, for example when other nutrients, light or temperature are limited, elevating the CO2 will have minimal effect (Poorter and Perez-Soba 2001). In addition to this, Minorsky 2002 showed that the effects of elevating CO2 can be variety-specific and not all cultivars will react the same if all else is equal.

In cannabis, an interesting study from 2008 compared temperature, light intensity and CO2 levels to uncover the most optimal criteria for indoor cultivation, particularly in terms of pharmaceutical cannabinoid production. The study showed that the overall productivity of photosynthesis was increased at elevated CO2 levels when all other parameters were optimal, and was measured by water use efficiency, intercellular CO2 and ratio of ambient CO2 to intercellular CO2 amongst other parameters (Chandra et al 2008).

Read more from PharmaSeeds: Do we still need master growers now that there’s more research on cannabis?

The authors concluded that under optimal light and temperature, cannabis species respond positively to elevated levels of CO2, and 0.07 per cent CO2, increased the photosynthetic rate by 44 per cent (Chandra et al 2008, Chandra et al 2011). Furthermore, as the CO2 levels increase, so does the photosynthetic output. 

This is fairly self-evident, but what is less obvious is the maximum levels at which one can increase CO2 before it has little or no further effect. If, like temperature and light intensity, there is a saturation point beyond which the effects can then become negative, then staying under that limit is crucial.

Maximum overdrive

As extensive work by Chandra and colleagues has shown, increases of up to 0.075 per cent CO2 can increase net photosynthesis, however the work does not explore levels over this range. In other species CO2 levels of up to 0.2 per cent (2000ppm) has been shown to improve the photosynthetic rate and increase yields (Silvola 1990, Hutchins et al 2007).

In Contrast, a recent study has shown that at over 0.09 per cent (900ppm) CO2 effects start to taper and may not provide further gains in the long term (Drag et al 2020). Based on the cultivation set-up in many successful licensed producers and experienced cannabis growers, although anecdotal, the advice states optimal CO2 levels are in the range of 0.12 to 0.2 per cent CO2 (1200-2000ppm).

However, optimisation on all fronts is key and small increases in CO2 will still show pronounced effects and so each cultivar, grow environment, feed system, and light set-up will need to be individually optimised in order to attain the maximum affects. In general, any supplemental CO2 will help with cultivation/yield optimisation, but there is no substantial difference at the high end and up to 0.1 per cent (1000ppm) would suffice in providing further gains (Canadell et al 2007).

Gary Yates
Chief scientific officer


New research could help cultivators control THC and CBD levels in crops

A team of researchers has used firefly genes to understand cannabis biology.



New research could help cultivators control THC and CBD levels in crops
Home » News » Production » How much CO2 do your cannabis plants need?

A better understanding of how cannabis produces THC means scientists could selectively knock out the enzyme that synthesises THC using genome editing techniques such as CRISPR. This would produce plants with lower levels of, or no levels of, THC.

With strict regulations surrounding the levels of CBD and THC in cultivated cannabis, controlling these levels is vital to prevent destruction of crops and lost licences, for example. 

Cannabinoids are produced by trichomes, the small, spikey and sticky protrusions on the surface of cannabis flowers, however, scientists know very little about how cannabinoid biosynthesis is controlled.

To discover the underlying molecular mechanisms behind trichrome development and cannabinoid synthesis, Yi Ma, research assistant professor, and Gerry Berkowitz, professor in UConn’s College of Agriculture, Health and Natural Resources received funding through the National Research Initiative from the US Department of Agriculture.

The research has been published in the journal Plants.

Read more: Cannabis cultivation – the artificial lighting minefield

Cannabinoid biosynthesis

Berkowitz and Ma, and former graduate students Samuel Haiden and Peter Apicella, have discovered transcription factors responsible for trichome initiation and cannabinoid biosynthesis. 

Transcription factors are molecules that determine if a piece of an organism’s DNA will be transcribed into RNA, and thus expressed. In this case, the transcription factors cause epidermal cells on the flowers to morph into trichomes. 

With this new grant, the researchers will continue to explore how these transcription factors play a role in trichome development during flower maturation.

Berkowitz and Ma will clone the promoters – the part of DNA that transcription factors bind to – of interest, and will then put the promoters into the cells of a model plant along with a copy of the gene that makes fireflies light up, known as firefly luciferase; the luciferase is fused to the cannabis promoter so if the promoter is activated by a signal, the luciferase reporter will generate light. 

Berkowitz commented: “It’s a nifty way to evaluate signals that orchestrate cannabinoid synthesis and trichome development.”

The researchers will load the cloned promoters and luciferase into a plasmid. Plasmids are circular DNA molecules that can replicate independently of the chromosomes. This allows the scientists to express the genes of interest even though they aren’t part of the plant’s genomic DNA. They will deliver these plasmids into the plant leaves or protoplasts, plant cells without the cell wall.

When the promoter controlling luciferase expression comes into contact with the transcription factors responsible for trichome development (or triggered by other signals such as plant hormones), the luciferase ‘reporter’ will produce light. 

Ma and Berkowitz will use an instrument called a luminometer, which measures how much light comes from the sample. This will tell the researchers if the promoter regions they are looking at are controlled by transcription factors responsible for increasing trichome development or modulating genes that code for cannabinoid biosynthetic enzymes. They can also learn if the promoters respond to hormonal signals.

In prior work underlying the rationale for this experimental approach, Ma and Berkowitz along with graduate student Peter Apicella found that the enzyme that makes THC in cannabis trichomes may not be the critical limiting step regulating THC production, but rather the generation of the precursor for THC (and CBD) production and the transporter-facilitated shuttling of the precursor to the extracellular bulb might be key determinants in developing cannabis strains with high THC or CBD.

Most cannabis farmers grow hemp, a variety of cannabis with naturally lower THC levels than marijuana. Currently, most hemp varieties that have high CBD levels also contain unacceptably high levels of THC. This is likely because the hemp plants still make the enzyme that produces THC. If the plant contains over 0.3% THC, it is considered federally illegal and, in many cases, must be destroyed. 

The researchers said: “We envision that the fundamental knowledge obtained can be translated into novel genetic tools and strategies to improve the cannabinoid profile, aid hemp farmers with the common problem of overproducing THC, and benefit human health.”

This knowledge could lead to the production of cannabis plants that produce more of a desired cannabinoid, making it more valuable and profitable.

As well as sharing these findings with cannabis scientists, industry, and growers, the researchers will incorporate this new knowledge into UConn courses on cannabis horticulture.

This grant will also support the training of undergraduates interested in cannabis research, providing them with the skills to enter the workforce.

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Planning application submitted for Isle of Man cannabis facility

The facility will include a science and innovation centre.



Planning application submitted for Isle of Man cannabis facility
SIRC CGI Isle of Man Eye Level (Peel NRE)
Home » News » Production » How much CO2 do your cannabis plants need?

Plans to kickstart the medical cannabis industry on the Isle of Man have progressed with the submission of a formal planning application for a cultivation facility on the island.

Earlier this year, Peel NRE proposed to establish a multi-million-pound science innovation and research centre (SIRC), sustainable energy park and medical cannabis facility on the Isle of Man.

The regeneration and clean energy specialist has now applied for planning consent for its proposals for the 72-acre site in between the A6 and A5 on New Castletown Road. 

The plan, which represents an investment of over £150m from Peel NRE, would create around 250 jobs across a range of skills from botany and technology to security and exports. More than 178,000 sqft of cannabis cultivation space will be created with around 102,000 sqft for research and development.

Read more: Isle of Man opens for business to the medical cannabis industry

Managing director of Peel NRE, part of Peel L&P, Myles Kitcher, said: “This is a game-changing opportunity for the Isle of Man to get ahead in a new and exciting industry that will bring many benefits to the Island and its people and we also hope that it will encourage more renewable projects in the area.

“As expected, our proposals have attracted a lot of attention and, we are pleased to say, significant support from the community during the extensive public consultation. This includes positivity around the emerging industry on the Island, the proposed campus-style development and new educational and career opportunities.

“We will continue to work with the community over the coming weeks and months as the project progresses and will be holding an industry event later in the year for businesses interested in finding out more about available opportunities.”

Read more: Proposal for medical cannabis facility put forward on Isle of Man

The proposals (22/00678/B) follow a change in the legislation of cannabis production and exportation on the island. The Isle of Man Government announced in June last year that opening the island up could make it “a world-leading exporter” of cannabis, and establish it as a global destination for science and technological excellence that will contribute to cutting-edge research into cannabinoids for pharmaceutical uses.

It will also set a gold standard for the burgeoning cannabis industry across the world and unlock partnerships in the public and private sectors.

Additionally, the scheme will feature a solar farm to power the site which would be the Island’s only grid-scale renewable project, contributing to the Isle of Man Government’s ambitions on climate change.

SIRC Isle of Man CGI – A5 Looking East (Peel NRE)

Peel NRE launched a public consultation to help shape the plans before the application was submitted to the Department of Environment, Food and Agriculture later this year, and has stated that it has had positive feedback from the Isle of Man community. 

Isle of Man Minister for Treasury, Dr Alex Allinson MHK, said: “The development of the Island’s medicinal cannabis sector is a key part of the Government’s ambitions to diversify the economy as well as creating a vibrant new sector to attract more investment and skills to the Isle of Man. 

“We are looking to create a world-class infrastructure and continue to welcome interest in developing this sector further.”

Speaking to Cannabis Wealth at the time of the proposal’s announcement, Laurence Skelly, President of Tynwald and Minister for Enterprise, commented: “Diversifying the economy is a significant part of the Isle of Man Government’s Island Plan and the development of Medicinal Cannabis for export is one of the key sectors to bring forward this diversification.

“The Island’s Medicinal Cannabis export proposition is to develop high-quality products and attract new investment through utilising the Island’s stellar reputation as a well-regulated jurisdiction.”

Planning application submitted for Isle of Man cannabis facility

SIRC CGI Isle of Man Aerial view (Peel NRE)

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MoU to establish medical cannabis production facility

The site will be based in Madrid, Spain.



MoU to establish medical cannabis production facility
Home » News » Production » How much CO2 do your cannabis plants need?

Kanabo has signed a Memorandum of Understanding (MoU)  for an indoor medical cannabis cultivation project in Spain.

The facility will enable 4,000kg per annum indoor cultivation and processing of cannabis. The facility, which is to be established in Madrid, Spain, will focus exclusively on medical cannabis.

Kanabo Group has formed an Israeli subsidiary company, Kanabo Agritec Ltd. (Agritec), which Kanabo Research Ltd, a wholly owned subsidiary of Kanabo Group, holds a 40 per cent shareholding, together with certain additional control rights over the strategic direction of the subsidiary.

Kanabo Agritec will enter into agreements with customers to offer consulting advice and support on cultivation, processing and production of medical cannabis products to organisations and entrepreneurs entering or already active in the cannabis market.

Read more: Kanabo Group extends GP Service contract with major UK retailer

CEO of Kanabo Group, Avihu Tamir, commented: “We are truly excited by today’s announcement. Agritec provides Kanabo Group plc an opportunity to realise the value of our extensive, existing intellectual capital in medical Cannabis cultivation and production, providing near-term consulting revenues.  

“Secondly, it provides us a way to diversify, secure and quality control our supply of medical-grade Cannabis that will always meet our exacting standards, avoiding any wasted margin from product that does not meet the grade.  

“In short, the new venture provides all the benefits and value of owning the cultivation supply chain, without the Capex and Opex requirement of building a cultivation operation ourselves.  Furthermore, Kanabo consumers will be guaranteed a consistent, highest quality supply of medical Cannabis products, at all times.”

Read more: Kanabo launches online CBD store for UK customers

CEO of Agritec, Ophir Shimshi, commented: “We are excited to combine Agritec’s team experience with Kanabo’s extensive R&D knowledge and expertise, to bring this powerful, full-service consultancy offering to market.  

“Agritec’s clients will benefit from Kanabo’s immensely valuable, tried, tested and proven playbook.  

“Our range of consulting services deliver every strategic and operational consideration required by enterprises and entrepreneurs who wish to take advantage of the immense growth opportunities this market has to offer.”

Kanabo has stated that Agritec provides the company with complementary near-term revenue opportunities and will offer Kanabo improved security of cannabis supply through a diverse range of suppliers, who will all adopt Kanabo’s high-quality manufacturing standards without Kanabo having to fund or become directly involved in cannabis cultivation.

Agritec customers will benefit from Kanabo’s services including: procurement, design and build of commercial scale, medical cannabis cultivation facilities; high-quality genetics and standard operating procedures for optimal medical cannabis cultivation; post-harvest services including offtake agreements with Kanabo Group; design and draft reporting and documentation filing services with the local authorities; and, local training and ongoing consulting services.

As per the terms of the MoU, Agritec may elect to receive up to 20 per cent ownership of the project based on the achievement of agreed milestones.

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