Cannabis water use efficiency (WUE) refers to the amount of water a cannabis plant uses to produce a certain amount of biomass or yield. Supplemental light, such as artificial lighting in indoor cultivation, can have significant effects on a plant’s water use efficiency. 

Here’s how:

1. **Increased Photosynthesis:** Supplemental light, especially in indoor growing environments, can enhance photosynthesis in cannabis plants. When plants can capture more light energy, they can convert more carbon dioxide and water into sugars and other organic compounds. This increased photosynthetic activity can potentially lead to improved water use efficiency, as more water is used for productive processes.

2. **Transpiration and Stomatal Regulation:** Transpiration is the process by which water is released from a plant’s leaves through small openings called stomata. These openings also allow for the exchange of gasses, including carbon dioxide and oxygen. When more light is available, plants often open their stomata wider to take in more carbon dioxide, which can lead to increased water loss through transpiration. This could potentially decrease water use efficiency if not properly managed.

3. **Optimal Lighting Management:** To maximize water use efficiency under supplemental light, it’s important to manage light levels effectively. Providing the right amount of light for the growth stage of the cannabis plant can help maintain a balance between photosynthesis and transpiration. Using light intensity and duration strategies, growers can optimize the plant’s ability to produce energy while minimizing excessive water loss.

4. **Growing Medium and Watering Techniques:** The choice of growing medium (soil, coco coir, hydroponics, etc.) and the watering techniques employed can also influence cannabis water use efficiency. Proper substrate choice and irrigation practices can help regulate water availability to the plant roots, preventing both water stress and waterlogging — both of which can impact WUE.

5. **Genetics and Environmental Factors:** Cannabis cultivars vary in their response to light intensity and other environmental factors. Some strains may exhibit better water use efficiency under supplemental light compared to others. Additionally, environmental conditions such as temperature, humidity, and CO₂ levels can also influence water use efficiency.

To push these limits, Callado and Hernandez regulated and analyzed the quantity and demand of resources and plant growth factors on an ongoing basis. They added light and water-control and measuring capabilities to every plot in the greenhouse, in addition to measuring temperature and evapotranspiration. 

As shown in Figure 1, the cannabis crops were grown under four light levels using two Current dimmable fixtures per plot supplementing sunlight. The L1000 PPB lighting fixtures delivered uniform supplemental light intensities of 150, 300, 500, and 700 μmol m⁻² s⁻¹ for 18 hours, while the Daily Light Integral (DLI) from the sun and LEDs were on average around 18, 30, 40, and 52 mol m⁻² d^-1. However, they present preliminary results for the three highest light levels. 

Moreover, the fertigation system was triggered independently at each plot when the pots’ water container capacities were 80%. This maintained consistent water and nutrient levels in pots regardless of the crop growth rates. Finally, the water use was quantified with load cells (scales) under the plants.

The Results and Conclusions

It’s easy to conclude from known knowledge that the impact of supplemental light on cannabis water use efficiency can be complex and depends on various factors, including light intensity, duration, genetics, and environmental conditions. Proper management of these factors, along with optimized growing practices, can help improve water use efficiency in cannabis cultivation. 

As the cannabis industry continues to evolve, research and experimentation in this area will provide more insights into how to achieve the best water use efficiency outcomes.

The results from Callado and Hernandez suggest that increasing the light amount not only increases the number of branches or cuttings per plant but also could increase the water demand (Figure 2b) and water-use efficiency to produce cuttings (less water per cutting) (Figure 2b). 

In other words, plants grown under an average DLI of 30 mol m^-2 d^-1 for 21 days produced close to 29 cuttings per plant, while plants grown at 52 mol m^-2 d^-1 produced 47 cuttings per plant from new secondary branches. 

Furthermore, plants grown under 30 mol m^-2 d^-1 produced 2.5 cuttings per every liter of water, while plants grown under 52 mol m^-2 d^-1 produced 4.3 cuttings per the same liter of water. This means the crops were more efficient at transforming water into branches under higher light intensities.

So how does this impact commercial growers?

The current research highlights the ability of a cannabis crop to use higher light levels to increase yield and water-use efficiency (higher yield per liter of water). The water-use efficiency for cutting production went from 2.5 to 4.3 cuttings per liter of evapotranspirated water when growing plants under 30 versus 52 moles of light per day, respectively. This would mean that to produce 100 cuttings using 52 moles of light, growers needed 23 liters of water instead of 40 liters under 30 moles of light. 

Figure 1. The top-left picture shows the experimental layout and greenhouse with two L1000 PPB fixtures at each plot or light treatment area (12 plots in total). The top-right picture shows a plot sensor that measures light from the two LED fixtures and the sun. The bottom pictures and arrows represent typical cannabis flower and plant production cycles.

Figure 2 shows the number of secondary branches or cuttings (a) water use per plant, (b) water-use efficiency (branches or cuttings per liter of water) and (c) under three light levels (30, 40, and 52 mol m⁻²) using LED lighting in addition to the sunlight.

To see other research from Hernandez and Callado, please follow this link:  www.gecurrent.com/eu-en/inspiration/researching-the-impact-of-supplemental-lighting-on-cannabis-production

Press Release – Resource Innovation Institute Executive Director Derek Smith previewed the forthcoming Cannabis Water Report as part of MJBizCon’s 2020 Associations Day on Tuesday, Dec. 1. The presentation provided information about past and current cannabis cultivation water usage and shared a sneak peek of proposed conservation benchmarks that will be relevant to cultivators, industry leaders, supply chain members, policymakers and media representatives. 

Water is a critical component of the cannabis industry, used for treatment, storage, fertigation and other non-cultivation activities like heating and cooling processes, fogging for humidification, pest-management, cleaning activities and more. The expansion of legal markets and increased consumer demand has driven huge cannabis production surges and increased water needs. 

“We live in an era of climate change where droughts are increasingly common,” Smith said. “A significant portion of cannabis cultivation is located in Western states, which will continue to be affected by water scarcity. It has never been more important to understand how our industry can improve efficiency. Previously, a lack of data stymied efforts to quantify water usage, but the transition to legal production provides a unique opportunity to establish new standards and key performance indicators that will help us do better in the future.” 

Whereas old data and press narratives based on the illicit market represented cannabis as an extremely “thirsty” crop, the new report notes that the regulated, legalized cannabis industry uses significantly less water than other major agricultural crops in California including cotton, tomatoes, wheat, and corn. 

“A portion of our research was focused on understanding why cannabis had received such notoriety as a water-intensive crop,” said Christopher Dillis, Postdoctoral Researcher at the Berkeley Cannabis Research Center. “We need to educate people about what is happening now, in the legal industry, and separate that from the old narrative around the illicit industry.

The report reveals that water use practices are highly diverse in the new regulated cannabis industry, and we hope that this new data leads to well-tailored regulatory policies that are responsive to this diversity.” The report also establishes that it is nearly impossible to normalize water usage per plant because it can vary so widely between indoor and outdoor cultivation, and depending upon location, growing techniques and other factors. As such, the report recommends that evaluation of future cannabis water efficiency be based upon canopy square footage, not plant count, as it has in the past. 

A partnership between Resource Innovation Institute, New Frontier Data, Berkeley Cannabis Research Center and members of RII’s Water Working Group, the full Cannabis Water Report is scheduled to be published in February 2021 and will establish a scientific understanding of how, and how much, water is used for cannabis cultivation. It will provide cultivators with insights, clarity and strategic recommendations for how to be more water-efficient, and ensure industry leaders, governments and media are accurately informed about the range of water practices in today’s dynamic and highly regulated cannabis market. 

To learn more about the 2021 Cannabis Water Report findings or to schedule an interview with Smith, please contact Shawna Seldon McGregor at 917-971-7852 or shawna@themaverickpr.com. 

The annual conference, happening on October 20-21, 2020, will maintain its focus on sharing the latest advances, research, and case-study findings regarding lighting optimization and efficacy, energy and cost savings, operations and environmental control systems, and strategies for integrating multiple ag-tech management technology platforms to attendees. Conference program announcements and more information will be available soon. Visit our website for the latest updates on registration, sponsorship and exhibit space.

ABOUT ENDEAVOR BUSINESS MEDIA

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Unlocking Potential

Using LED Grow Lights for Better Cannabis Yields by Hans Spalholz, PhD

Traditionally, cannabis growers have relied on high pressure sodium (HPS) systems for their lighting needs. Advancements in LED technology, coupled with increased demand and the need to reduce expenses, accelerate turns and save energy, make LED fixtures a viable replacement. Despite their
advantages, there is a learning curve as you change from HPS to LED and several things to consider.

This guide will walk you through things to keep in mind, as well as detail the benefits of LED growth.

Fill out the below info to download the whitepaper.
(We value your privacy. This content has been created by GE Current, A Daintree Company, with support from Hort Americas and they will have access to your information.)

The lab’s license is to research hemp, but these principles apply to marijuana, including sativa and indica. Some of Bruce’s answers in this video are based on what the research is showing so far, but further tests are underway. As this is a very hot topic right now, we will do our best to monitor questions posted in the comments below and ask Bruce to answer them in future videos.

Links:

* Dr Bruce Bugbee’s bio: https://en.wikipedia.org/wiki/Bruce_B…https://psc.usu.edu/directory/faculty…

* Apogee PPFD Handheld meter version – https://www.apogeeinstruments.com/mq-…

* USB Smart Sensor version – https://www.apogeeinstruments.com/sq-…

* All other models – https://www.apogeeinstruments.com/qua… Apogee PAR-FAR and Red – Far-red sensors: https://www.apogeeinstruments.com/red…

Apogee microCache Bluetooth micrologger: https://www.apogeeinstruments.com/mic…

Design Light Consortium: https://www.designlights.org/

Press Release — Emeryville, California  — LumiGrow announced today the release of their vertical grow light solutions designed to create your most profitable high-density cultivation yet.

“Our newest BarLight Series is precision built for high-yield cannabis growth and commercial extraction,” said Jay Albere, LumiGrow CEO.  “Growers have been patient for LumiGrow to release a vertical cannabis solution – and we’re proud to announce this addition to our award-winning products.  We’re bringing over 10 years of grow light innovation into this one and there’s nothing else like it on the market.”

The BarLight smart fixtures allow growers to build their own high-density lighting environment for any growth stage.  One LumiGrow EasyRail mount supports either one or two BarLight fixtures spread over a 4’ by 8’ vertical rack.  This flexibility is cheaper to deploy than the leading vertical cannabis solutions, reducing the amount of equipment required for full cycle production.

BarLight comes in two spectrum options for white or pink light and uses patented wireless control technology to adjust the LEDs for custom plant development.

“LumiGrow smart fixtures already have proven ability to increase quality and improve biochemical profiles,” said Jay,  “We’re introducing the next generation of lighting to vertical cannabis cultivation, built for creating a successful cannabis business at any scale.”

Learn more about BarLight at www.lumigrow.com/BarLight

About LumiGrow

LumiGrow revolutionized horticulture in 2008 with the introduction of the first smart LED grow lights in North America.  Today, LumiGrow leads the world forward in grow light innovation with their TopLight and BarLight smart fixtures designed to maximize a growers’ profits.  The LumiGrow lights are wirelessly controlled by their smartPAR software to optimize yield, quality, and custom plant traits.  LumiGrow lights can be fine-tuned for greenhouse environments by pairing with their award-winning smartPAR Light Sensor to ensure consistent crop production year-round at the lowest energy cost.

LumiGrow has the largest install-base of smart LED grow lights in North America with installations worldwide.  For more information about LumiGrow, please see www.lumigrow.com

LumiGrow is a registered trademark of LumiGrow, Inc. All other marks are the property of their respective owners.

Indoor Ag Science Café is supported by USDA SCRI grant program and designed to create a precompetitive communication platform among scientists and indoor farming professionals. The Café presentations are available from YouTube channel: https://www.youtube.com/playlist?list=PLjwIeYlKrzH_uppaf2SwMIg4JyGb7LRXC   Contact Chieri Kubota at the Ohio State University (Kubota.10@osu.edu) to be a Café member to participate. 

The Agriculture Improvement Act of 2018, commonly referred to as the 2018 Farm Bill, has legalized the production of hemp. The Agricultural Marketing Service (AMS) is the lead USDA agency to administer the new USDA Hemp Production Program. AMS, which is developing regulations to implement the 2018 Farm Bill provisions announced in the June 24, 2019, Federal Register that it expects to release a final rule in August

Growers in states that have already legalized hemp have been growing the crop according to their state’s regulations. Industry consultant John Dol at CannabiDol has been contacted by both greenhouse vegetable and greenhouse ornamental plant growers about switching to both hemp and cannabis.

“There are people who have been in the vegetable or ornamental plant industry who have made the switch,” Dol said. “There are also people who have been growing cannabis for some time and are looking to expand to a larger production facility.

“One of the challenges is not everyone has the ability/skill set from a managerial point of view. People in the greenhouse industry who have been exposed to managing people, crop scheduling and facility management have found it easier to make the transition to large scale cannabis production. However, specific cannabis plant knowledge will be stronger with the traditional industry players. I think a combination of both these factors in a management team will set a growing operation up for success.”

Differences in production scheduling

Dol said comparing ornamental plant and vegetable production operations, the ornamental growers have an edge in regards to planning because many vine crop vegetable growers only plant once a year.

“Greenhouse tomato growers plant their crops and then they basically maintain them,” he said. “Many greenhouse tomato growers in the Northeast are going to produce a mono crop which means planting in December or early January and then maintaining the same crop until November. Once the crops are finished, the old plants are removed, the greenhouses are cleaned and new crops are planted.

“Many greenhouse ornamental growers produce hundreds of different crops throughout the year. Similarly with cannabis there may be six cycles per year and there is a lot more planning involved with it. In terms of production scheduling, the transition to cannabis should be easier from the ornamentals side.”

Dol said depending on the cannabis strains being produced, there could be crop cycles every eight to nine weeks. Longer cycle times are available but will diminish overall yield.

“Most greenhouse growers, both vegetables and ornamentals, buy their starter plants from propagators,” he said. “In most cases, cannabis growers have to grow mother plants, cut clones and grow vegetative plants before flowering starts. These are all planning cycles that have to coincide with the flower room schedule. Cannabis production involves multiple grow rooms which makes the planning much more intense.”

Differences in labor intensity

When it comes to the differences in labor tasks involved with growing these crops, Dol said producing cannabis is between vegetable and ornamental crops.

“The work that has to be done with cannabis is less than what has to be done with a greenhouse tomato crop,” he said. “Producing a tomato mono crop for 10 months, the weekly labor tasks include pruning, lowering, deleafing and clipping every plant. That is just the maintenance labor that has to be done on the plants. There is also harvesting and packing.

“These tomato production activities happen from winter to fall five days a week. During the summer and early fall harvesting happens six days a week. A 24-acre greenhouse may have 300,000 plants in it. That is a lot of labor hours needed to produce a tomato crop.”

Dol said with cannabis crops there is less labor involved because there is less manipulation of the plants.

“There is a lot less labor involved with cannabis,” he said. “With cannabis once the plants begin to flower there may be three deleafings, harvesting and packaging. Depending on the production strategy, bigger cannabis plants take more labor and growers may want to do lower planting densities which involves having to bend the plants more. I prefer to have higher density plantings.”

Dol said greenhouse ornamental crops are the least labor intensive of the three crops.

“Unless the ornamental plants have to be pinched, disbudded or treated with PGRs and/or pesticides, the plants are put in the greenhouse, allowed to grow and then come out at the other end when their ready to sell,” he said.

Differences in pest control

Dol said greenhouse vegetable growers looking to produce cannabis have an advantage over ornamental growers when it comes to disease and pest control.

“Greenhouse vegetable growers have the edge because they have been exposed more to integrated pest management using biologicals and cultural methods to remedy these types of issues,” he said. “Since tomatoes are ready-to-eat products, most vegetable growers only spray as a last resort. This is something that also has application in cannabis production.”

Dol said with cannabis the control methods and products are regulated by individual states, which is one of the difficulties especially for companies with multi-state operations.

“Some states are stricter than others,” he said. “Some states may allow the use of natural oils like garlic oil or rosemary oil. Some states are allowing cannabis growers to use what can be applied to food crops. One of the issues is there hasn’t been a lot of product research done on cannabis because it has been an illegal crop for such a long time.

“For agricultural field crops there are many more acres in production so there are more pesticides and fungicides being used than in greenhouses. Greenhouse growers have always had a harder time getting products registered because there is not as much money in it for the companies developing and labeling the products. The cannabis production space currently is much smaller than the greenhouse vegetable or ornamental space. For the chemical companies it is very expensive and time consuming to have a product reregistered or relabeled for use on a specific crop. Now that hemp is legal, I expect more chemical companies will be looking at re-registering their products. If the hemp is used for medical cannabidiol (CBD), then the regulations are going to be stricter than if the hemp is used for fiber to make clothing or some other products that are not ingested.”

Learning the nuances of growing

Dol said he expects most of the greenhouse growers who are looking to start producing hemp are doing it for the production of CBD.

“If a grower wants to be a year-round producer, in most climates some kind of controlled environment is needed,” he said. “A greenhouse would be the best way to do that because the environment can be completely controlled. For growers producing only outdoors they may need to grow on many more acres to produce the same volume as in a greenhouse where production can occur year round. Water resources are used much less in greenhouses. And from a product quality/safety perspective greenhouses offer much more protection.

“Cannabis is a different plant than other crops that greenhouse vegetable and ornamental growers have produced before. All of the same factors, including light, water, nutrients and carbon dioxide that are required with tomato or mum crops, would apply to cannabis. It’s a matter of understanding what the plants need and also understanding from one cannabis strain to another the needs may be different. Most differences are in irrigation management and crop duration. There are nuances that have to be learned for the different cannabis strains.”

For more: John Dol, CannabiDol, cannabidol420@yahoo.com. 

This article is property of Urban Ag News and was written by David Kuack, a freelance technical writer from Fort Worth, TX.

Heidi Lindberg, Michigan State University Extension
Industrial hemp (Cannabis sativa L.) is cannabis cultivated to produce fiber, grain, biomass, or non-intoxicating medicinal compounds, such as cannabidiol (CBD). 

Recently, the 2018 Farm Bill legalized the production of industrial hemp in all 50 states. Therefore, many greenhouse and nursery producers are now looking at industrial hemp as a new opportunity for their businesses. 

Join Michigan State University Extension for a webinar series to cover the basics of growing industrial hemp and considerations for growers considering entering the industry of this burgeoning crop. Note: Half of the final webinar will cover Michigan-specific licensing information. 

To learn more, read: Exploring opportunities: Growing industrial hemp in Michigan

To sign up, visit:Industrial Hemp Production 101