OptimIA researchers are studying the impact light and its interaction with other environmental parameters can have on indoor leafy greens production.

When members of the OptimIA project contacted controlled environment agriculture industry members about their concerns about the growing environment, light was at the top of the list. The OptimIA’s project objectives were based on feedback from indoor farm representatives, growers and lighting manufacturers related to the production of food crops.

“Lighting is one of the biggest costs not only for purchasing the fixtures, but also for operating them,” said Erik Runkle, horticulture professor at Michigan State University and director of the OptimIA project. “Operating lighting fixtures is a big sink of electricity and therefore a major operating cost. Another large operational cost for indoor farms is air conditioning, but typically it is not as big as lighting.

“Looking at some of the other environmental control issues that indoor farms have had in the past, excessively high humidity was caused by inadequate HVAC systems. Humidity and temperature are tightly linked because temperature influences how much moisture the air can hold. We thought if we study humidity we should also study temperature. Temperature dictates the rate of development of plants.”

Runkle said carbon dioxide gets added to the environmental mix when looking at light intensity.

“The benefit of carbon dioxide increases as light delivered to plants increases,” he said. “Early on when we started this project we were delivering, what is considered by today’s standards, relatively low light intensities, so the value of adding supplemental carbon dioxide was minimal.

“Indoor farms are increasingly delivering higher light intensities, in which case carbon dioxide becomes more important. We knew that carbon dioxide is one of the factors to consider with indoor farms, but it was not considered one of the top factors like light, temperature and relative humidity.”

Divvying up the research projects

Prior to receiving $2.4 million in USDA funding in September 2019 for the OptimIA project, Runkle had started the Controlled-Environment Lighting Laboratory at Michigan State.

“The lab is a unique facility that has capabilities that few other researchers at the time had,” he said. “Having access to the lab, it made sense for me to focus on light quality or the different colors of light and how they affect growth. A lot of what each team member focused their project research on was imposed by their expertise in the topic and whether they had the facilities to conduct the research.

“Developing these research facilities is quite expensive, and usually with these types of research proposals, large equipment budgets are not favorably reviewed. OptimIA team members thought rather than requesting a large equipment budget, we would determine who had the equipment and facilities to do lighting studies. Also, we looked at who had past research expertise so it just made sense for them to perform the various environmental studies.”

Light was the single environmental factor that the OptimIA researchers keyed in on. Every member of the OptimIA team, other than its ag economists, has done some type of light manipulation research.

Studying different aspects of light

The three major areas of light study were: 1. light intensity or the brightness of the light; 2. the different colors of light, primarily blue light, far-red light and ultraviolet (UV) light, and 3. the uniformity of light, which is often an overlooked dimension of light.

“The brightness, the colors and how many hours light fixtures are operated per day are usually the focus of light research,” Runkle said. “Light distribution uniformity is often overlooked, but we have seen that uniformity can be an issue in indoor farms.

“For OptimIA researcher Cary Mitchell at Purdue University one of the focal points of his research is the positioning of light fixtures trying to reduce the amount of light that spills into areas where there are no plants. There is light that reaches the target within a crop, but there is also light that spreads out beyond where the plants are located. This is light that is wasted because it doesn’t reach the plants. Trying to deliver as much light from the fixtures to the plants can improve efficiency because the light is reaching the plants and is not wasted.”

The relationship between environmental parameters

OptimIA researcher Roberto Lopez, associate horticulture professor at Michigan State, is studying the interaction of light, temperature and carbon dioxide on leafy greens production.

“Previous research between these environmental parameters had been done in greenhouses,” Lopez said. “We are using walk-in growth chambers to provide more control over the light environment. Unlike in a greenhouse, there isn’t any sunlight in indoor farms that can impact the results.

“We wanted to see how carbon dioxide and temperature interact with light. Light and temperature studies can be done in a greenhouse, but carbon dioxide studies are going to be challenging. Being able to do the studies indoors makes it more feasible.”

Prior to the start of his OptimIA studies, Lopez was using dimmable white light LEDs in the growth chambers.

“Signify provided us with dimmable LED light fixtures which allow us to manipulate the spectrum,” he said. “With the new fixtures we not only can deliver white light, but we can change the spectrum whenever we need to during the growth cycle.

“In some of our later studies we have been looking at manipulating the color of the foliage with the spectrum. This allows us to start growing the plants under white light and towards the end of the production cycle we can change the light spectrum to potentially manipulate the color of the foliage or increase the amount of anthocyanin and other nutritional compounds.”

Impact of light intensity

Lopez said the impact of light intensity on lettuce production appears to be cultivar dependent.

“With some lettuce cultivars we found 150 micromoles of light is sufficient and with others we had to increase the light level to 300 micromoles to achieve an increase in yield,” he said. “With other cultivars we found by doubling the amount of light there isn’t an economic benefit to increase the light intensity. It wasn’t worth increasing the light intensity in terms of the yield that we were able to achieve, at least when based on our economic assumptions.”

Lopez said some indoor farm growers of leafy greens are increasing light intensity levels to 600 micromoles.

“Is that light level necessary? In our opinion—no,” he said. “It doesn’t make sense because at some point the plants become saturated with light and the growers are wasting money. The plants may not be utilizing the light if the other environmental parameters are not adjusted accordingly.

And economically it doesn’t make sense. To achieve these light levels requires more lighting fixtures and there are increased electrical costs.”

Impact of light color

Results of OptimIA studies have confirmed the importance of blue light on plant growth.

“Blue light has a strong effect on inhibiting leaf size, which means plants are smaller compared to plants grown under lower intensities of blue light,” Runkle said. “Blue light also controls the coloration of leaves as well as other quality attributes, including the nutrient density and perhaps taste.

“OptimIA researchers weren’t the only ones to discover the effects of blue light, but we are building upon other blue light research to learn how important it is and what different intensities of blue light do to leafy greens crops.”

Runkle said the light spectrum or the color of the light is more important in indoor farms than in greenhouses.

“In a greenhouse there is sunlight and the ability to change the spectrum is influenced by how much sunlight is entering the greenhouse,” he said. “During winter when supplemental lighting is used the most in greenhouses, is when lighting is most valuable and the ability for the spectrum to influence plant growth is also the greatest. Because blue light has such a strong effect on the shape of plants, the percentage of blue light chosen for an indoor farm can be a much bigger decision than the percentage of blue light in a greenhouse.”

Runkle said the verdict is still out on whether or not far-red light is necessary in indoor farms.

“Far-red light is similar to blue light and how much light should be given to plants,” he said. “Blue light and far-red light act antagonistically. Far-red light increases leaf expansion, which often leads to more growth because the plants can intercept more light. This growth increase is somewhat countered by a decrease in the quality. Plants exposed to far-red light typically produce leaves that are lighter green in color or the leaf texture is affected, including thinner leaves and leaves that are not as crisp or firm.

“Applying far-red light can lead to tradeoffs between maximizing biomass and plant quality. There are usually tradeoffs between the harvestable index or what can be harvested and the quality of that harvest.”

Verdict still out on UV light

There has not been a lot of research done with UV light in the indoor production of leafy greens.

“There are various reasons research with UV light hasn’t been done,” Runkle said. “LEDs that deliver UV light are not very efficient and they typically don’t have a very long life span.

“We have done a few studies looking at the efficacy of using UV-A light compared to blue light. We found that blue light and UV-A light are similarly effective in terms of plant responses. But blue light is a lot cheaper to deliver. Blue light LEDs are cheaper and last a lot longer. If the same response can be achieved with blue light LEDs than UV-A LEDs, then at least in our research we haven’t seen any reason to include UV-A light.”

Relationship between light and carbon dioxide

Ambient carbon dioxide level is about 400 parts per million (ppm). Lopez did studies with lettuce supplementing plants with 400, 800 and 1,200 ppm.

“Going from 400 ppm to 800 ppm there was an increase in yield,” he said. “Going above 800 ppm there wasn’t much of an appreciable increase. There is definitely a limit and beyond 800 ppm, there wasn’t any economic benefit as well.

“Whenever any of these three environmental factors are limiting, a grower could provide optimal light levels and the optimal temperature, but if carbon dioxide is limiting, then ultimately photosynthesis is limited, which impacts crop yields. It’s important to measure, monitor and control all three parameters. In a greenhouse it is challenging to do this. With an indoor farm it is possible to have much more control of these environmental parameters.”

For more: Erik Runkle, Michigan State University, Department of Horticulture; runkleer@msu.edu; https://www.canr.msu.edu/people/dr_erik_runkle.
Roberto Lopez, Michigan State University, Department of Horticulture; rglopez@msu.edu; https://www.canr.msu.edu/people/dr_roberto_lopez?profileDisplayContent=contactInfo.

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

If you have any questions about this survey, please contact Simone Valle de Souza, from Michigan State University, phone: (517) 884 8042 or email: valledes@msu.edu.

Roberto and Kellie work on lighting technologies for basil production and shared their most updated research on light intensities during young seedling stage of basil, affecting flavor profile and consumer liking in addition to yield and quality. Indoor Ag Science Café is an outreach program of our project OptimIA, funded by USDA SCRI grant program (http://www.scri-optimia.org). The café forums are designed to serve as precompetitive communication platform among scientists and indoor farming professionals. 

The Café presentations are available on their YouTube channel: https://www.youtube.com/playlist?list=PLjwIeYlKrzH_uppaf2SwMIg4JyGb7LRXC   

Contact Chieri Kubota at the Ohio State University (Kubota.10@osu.edu) to become a Café member and be able to participate. 

Leafy greens include commonly consumed vegetables such as lettuce, kale, and microgreens. Production challenges outdoors have led to interest in growing these specialty crops hydroponically in controlled environments, such as indoor farms. However there is little information on whether this is economically viable. Capital and operating costs can be significant for startups, especially as it relates to light-emitting diodes (LEDs) and cooling systems. Leafy greens are a good candidate for indoor farming because they can be grown rapidly and in relatively small spaces. Indoor environments are heavily controlled, so growers aren’t constrained to a small geographic area within the U.S. There are, however, other geographic concerns.

The team and its collaborators have three major goals:

• Define optimal profitability based on yield and other high-value attributes of the plants, such as nutrition content
• Optimize indoor environmental conditions, such as humidity, air movement, temperature, light and carbon dioxide concentration, to increase yield and high-value attributes
• Encourage indoor farming stakeholders to collaborate with academic and industry groups that are working in controlled-environment agriculture.

The long-term project goals are to help integrate indoor farming into the specialty-crop segment of agriculture in the U.S.; to increase the sustainability and hence profitability of this rapidly emerging sector; and to locally produce leafy greens that have higher quality attributes. To this end, our economists will better understand operating and capital expenditures (capex), and define risk and production scenarios that are most profitable. Our horticulturists and engineers will improve production efficiency, product quality, and value-added attributes of leafy greens for reliable, consistent, year-round production. In addition, the team will design and test more effective localized air-distribution methods suitable for indoor production systems, as well as develop strategies to better manage humidity around plants to reduce tip burn. While the project focuses on leafy greens, the results will also inform a wide range of controlled-environment growers through the development of growth recipes, strategies for nutritional content and anthocyanin enhancement, environmental management recommendations, and insights for economic sustainability as well as market and consumer perception of locally produced crops.

For more information, visit the project website at scri-optimia.org.

The GLASE Webinar Series features the latest technological innovations and best practices in the controlled environment agriculture (CEA) industry providing the participants an opportunity to discover new solutions and to connect with industry experts. The webinars are free.

July 25 • 2-3 p.m. EDT – REGISTER HERE
Supplemental greenhouse lighting during propagation
Presented by Erik Runkle and Roberto Lopez, Michigan State University

Aug. 22 • 2-3 p.m. EDT – REGISTER HERE
National greenhouse database
Presented by Erico Mattos, GLASE

Sept. 26 • 2-3 p.m. EDT – REGISTER HERE
Humidity control in greenhouses and other indoor plant environments
Presented by Nadia Sabeh, Dr. Greenhouse, Inc

Oct. 24 • 2-3 p.m. EDT – REGISTER HERE
Strawberry and tomato responses to light and CO₂ control
Presented by Neil Mattson and Jonathan Allred, Cornell University

Nov. 21 • 2-3 p.m. EDT – REGISTER HERE
Off-season strawberry production under controlled environments
Presented by Chieri Kubota, Ohio State University

Dec. 2019
LED basics applied to horticulture lighting systems
Presented by Bob Karlicek, Center for. Lighting Enabled Systems and Applications

Jan. 2020
Horticultural lighting systems energy-savings calculations
Presented by Neil Mattson, Cornell University, and A.J. Both, Rutgers University

Feb. 2020
Influence of temperature and daily light integral on culinary herb production
Presented by Roberto Lopez and Kellie Walters, Michigan State University

March 2020
Lighting approaches to maximizing profits
Presented by Marc van Iersel, University of Georgia

Technical Articles 

The GLASE Technical Articles series delivers the latest GLASE research updates. In a series of 10 publications researchers from Cornell University, Rensselaer Polytechnic Institute and Rutgers University will cover a wide range of applied CEA technologies including new LED lighting systems, integrated CEA control systems, measurement standards, energy modeling and commercial case studies. The articles will be published on a monthly basis.

• July 2019 – New horticultural Research LED lights  
• Aug. 2019 – Light and shade system implementation (LASSI)  
• Sept. 2019 – Light measurements and distribution in tall canopy crops
• Oct. 2019 – A new greenhouse light spectral acquisition system
• Nov. 2019 – Plant responses to integrated light and CO₂ control
• Dec. 2020 – Horticultural lighting standards
• Jan. 2020 –  Remote chlorophyll fluorescence  detection system
• Feb. 2020 – Controlled environment agriculture (CEA) energy modeling
• March 2020 – A modified infra red gas analyses for light response curves
• April 2020 – GLASE commercial pilots – A case study

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

For more info, contact Chieri Kubota at the Ohio State University to be a Café member and participate.

If you are growing crops hydroponically in deep-flow or raft systems, one of the last things you want to see is an unusually low or empty tank. It is not uncommon for nutrient solution levels to be reduced by evaporation and transpiration, but when levels decrease rapidly, there may be a larger issue.

A common issue in nutrient film technique (NFT) or with drip systems is a leak from the tube delivering the nutrient solution. Another possibility is a crack in a tank or tube. However, what could be the cause if you do not see a leak? A less-intuitive issue that may occur is siphoning.

Watch out for siphoning if you are using air stones or tubes for oxygenation in deep-flow or raft systems or reservoir tanks. Siphoning may happen if the air pump is not supplying air flow due to a broken tube or the power going out. If the nutrient solution is siphoned into the pump, damage to the pump may occur. Siphoning may also be a result of air stone tubes breaking or coming loose from the air pump.

To prevent this issue, position air pumps higher than the nutrient solution reservoir. This will stop siphoning from a pump or power failure. However, if the tubing becomes loose, cracks, and falls outside of the tank beneath the water level siphoning may still occur. If feasible, consider installing in-line back flow prevention valves. Be aware this may be a problem and, if the nutrient solution is suspiciously low, check for siphoning.

About the Author:
Kellie Walters and Roberto Lopez Assistant Professor and Floriculture/Controlled Environment Extension Specialist(Michigan State University), and PhD candidate (Michigan State University), Roberto G. Lopez is an Assistant Professor and Floriculture/Controlled Environment Extension Specialist at Michigan State University. He has an appointment in research, teaching and extension. His area of expertise is; controlled environment specialty crop production; Lighting applications for greenhouses and indoor vertical production; light-emitting diodes; young plant propagation.

Originally written by e-Gro (Heidi Wollaeger) on Jan 24, 2019

Dr. Mary Hausbeck in the Department of Plant, Soil and Microbial Sciences at Michigan State University and her colleagues have released a new guide for disease management for vegetable and herb crops. The new guide provides the following information about each registered product for vegetable transplants and herbs: 1) active ingredient, 2) trade name of the product, 3) FRAC code (numbers based on the mode of action of the active ingredient), and 4) re-entry interval. The disease recommendations are grouped by crop groups: 1) Brassica, 2) Cucurbit, 3) Leafy, 4) Fruiting, and 5) Herbs. Within each crop grouping, the table lists whether it is registered for use for: bacterial blight, downy mildew, leaf spot, powdery mildew, Phytophthora, Rhizocontia, or Sclerotinia.

Dr. Mary Hausbeck is the Associate Chair for Administration, University Distinguished Professor, and Extension Specialist in the Department of Plant, Soil and Microbial Sciences at Michigan State University.

Researchers from top universities have come together to create this series designed to assist growers of floriculture crops with nutritional monitoring.

Below, we wanted to share the factsheet for lettuce!

e-Gro Nutritional Monitoring Factsheet for Lettuce PDF

For more, visit fertdirtandsquirt.com

Ornamental plant growers in Michigan are looking to extend their selling season by producing greenhouse vegetables. Many of these growers are looking to take advantage of the increasing interest in locally-grown produce.

Michigan State University Extension greenhouse and floriculture outreach specialist W. Garrett Owen said he works with ornamental growers who produce bedding plants, vegetable transplants for field production and retail sales and who also finish vegetables for retail sales.

“A lot of the growers who I work with who grow vegetable transplants grow cole crops, including cabbage and kale, which are then field transplanted,” Owen said. “Few ornamental growers who I work with produce vine crops of tomatoes and English cucumbers. There is also a grower who is experimenting with peppers and eggplant. The majority of these growers also produce field vegetables.

They grow the ornamentals in the spring and then produce field vegetables. They had the available greenhouse space and felt they could earn additional revenue by adding vegetables.

“In general the smaller growers I’m working with may have as few as one or two hoop houses or greenhouses. The larger growers may have up to an acre of greenhouse vegetable production. I work with a lot of small grower-retail operations. They grow spring ornamentals and also have a vegetable farm as well. They typically sell the vegetables through their retail garden centers. After the spring bedding plants are sold they focus on the vegetables. Some also sell at farmers markets and some have contracts with local restaurants and grocery stores. The product for these growers, who are located in southeast Michigan, is based on what they’re comfortable growing and what their customers are looking for.”

Owen said the growers are marketing their produce as an early crop ahead of what would be field grown.

“These growers can provide fresh tomatoes and other produce earlier than what can be field harvested,” he said. “They also have better control in regards to quality. It’s the early harvest, meeting the early market demand and having a superior quality product.

“When I was visiting these growers in April and May they were already harvesting tomatoes. After the annuals are sold then they are growing the greenhouse tomatoes. That goes all the way until the fall and then they rip those out and give the greenhouses a rest period. They can clean up the greenhouses and prepare them for the next spring production. They make sure that no pests or diseases are carried over through the winter. There is also one ornamental grower producing tomatoes year-round in conjunction with growing ornamentals.”

Adding vegetable production

Owen said some of the growers started producing vegetables because they had empty greenhouse space and wanted to get another turn to increase their profits.

“For many it was a trial-and-error project,” he said. “They wanted to see if they could grow greenhouse vegetables with the inputs, including substrates that they were already using for their ornamentals.

“The vegetables are separated from the ornamental crops. The crops are separated in the greenhouses whether it is a separate greenhouse used for vegetables or the greenhouses can be closed off with automatic doors or plastic curtains.”

Owen said the ornamental growers are using different production methods to grow the vegetables. Some are using large containers, including 2-, 3- or 4-gallon nursery containers filled with a commercial growing mix.

“The smaller growers who are doing finished vegetables are using bag culture with a commercial substrate,” he said. “They lay the bags out in the greenhouse and grow the vegetables in the bags.

“Some growers are using flower bulb crates that are filled with a commercial substrate. They plant in the substrate and then cover the crates with the bags the substrate came in. Some are also growing in Bato buckets. The substrates include commercial peat-perlite mixes, coir and some are using a bark-based coir mix to provide more drainage.”

Challenges of greenhouse vegetable production

Even though these ornamental growers were growing vegetable transplants for field production and retail sales, Owen said they faced some challenges when trying to finish the vegetables under greenhouse conditions.

“Since these vegetables crops were being grown in a protected environment and they are edible crops, some of the chemicals that can be sprayed on greenhouse ornamental crops or what can be sprayed on outdoor vegetables weren’t labeled for greenhouse crops,” Owen said. “They had to find out what they could use to control pests and diseases indoors. The growers are using conventional production methods and are not growing organically. They do try to implement organic practices when possible such as pest and disease control.

“The majority of pests and diseases that they are trying to control outdoors are the same as the ones they are trying to control indoors. Some of those pests and diseases are also the same ones they are trying to control on their ornamental crops.”

Owen said one of the biggest challenges these growers faced was trying to grow greenhouse vegetables in the same growing mixes they were using for ornamental plants.

“The crop time for the ornamentals is anywhere from four to eight weeks,” he said. “Trying to grow a greenhouse crop like tomatoes for months in the same ornamental growing mix caused some issues. For example, with a peat-perlite mix settling occurs and the particle size degrades over time. The chemical and physical properties are going to be altered, including air space and container capacity. Some of the air space in the substrate is lost from settling or compaction. Just because a substrate can be used to grow ornamentals in a short crop time, there are challenges using the same mix for longer-term greenhouse vegetables.

Owen said none of the growers who added greenhouse vegetables changed substrates. One grower did add more peat in order to increase water retention.

One of the biggest adjustments the growers had to make for greenhouse vegetables was related to pH management and keeping the pH within the recommended range during the longer crop cycles.

“To make pH adjustments some of the growers did alter or chose a fertilizer based on the crops,” he said. “Blossom end rot on tomatoes was a challenge for one grower. That was helped by altering the pH and changing the fertilizer that was used.

“Irrigation was another issue, including how they were watering and how often they were watering. This also varied based on the age of the crop, the substrate they were using and how they were growing the crop. There wasn’t just one answer for these growers because they were growing different crops, how they were growing them and at different stages in the production cycle. We had to tailor the changes based on their method of growing.”

For more: W. Garrett Owen, Michigan State University Extension, East Lansing, MI 48824; (248) 347-3860 Ext. 202; wgowen@msu.edu; http://msue.anr.msu.edu/experts/garrett_owen.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Are You a Hydroponic Grower of Food Crops? Michigan State and Iowa State University Researchers Need your Input!

Controlled environment agriculture (CEA) production researchers Roberto Lopez and Kellie Walters at Michigan State University and Christopher Currey at Iowa State University have developed a survey to gain a better understanding of current hydroponic food production practices and needs to focus their future research and extension efforts. This survey focuses on which crops are being grown, plant propagation methods, growing environments and technologies, and what areas of research would benefit your operation. Make your needs heard by taking this short survey (less than 10 minutes)!

https://www.surveymonkey.com/r/LNYFDVY

Helping growers learn about the latest advancements in supplemental, photoperiodic, and sole-source horticulture lighting and making the best decisions for their plants and business.

Learn from Michigan State University (MSU) leading lighting experts and researchers Erik Runkle, PhD, and Roberto Lopez, PhD, as they showcase their current studies and students in the MSU Research Greenhouses and then breakdown their wealth of knowledge and research into business-relatable terms.

Get educated then make a better informed and smarter decision on how to invest in greenhouse and indoor lighting technologies for vertical farms, tissue culture facilities, hydroponics, etc.

Click below for presentation PDFs:

Investing in LEDs, Runkle, Michigan St. Univ.

Photoperiodic lighting, Meng and Runkle, Michigan St. Univ.

Sole-source Lighting, Lopez and Park, Michigan State Univ.

Supplemental Lighting, Lopez, Michigan State Univ.