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

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.

Scientists, university researchers, graduate students and industry representatives from 25 countries attended the 8th International Symposium on Light in Horticulture at Michigan State University.

Michigan State University hosted the 8th International Symposium on Light in Horticulture from May 22-26, 2016. This was the first time the symposium, which began in 1969, was held in the United States. The symposium was attended by 250 people from 25 countries.

Michigan State horticulture professors Roberto Lopez and Erik Runkle were the organizers and co-conveners of the symposium.

“The symposium is part of the International Society for Horticultural Science,” Lopez said. “The light symposium is held every three to five years.”

Lopez, who is the chair of the ISHS Workgroup Light in Horticulture, said he and Runkle began working on the symposium three years ago.

“ISHS is similar to the American Society for Horticultural Science, but ISHS is for international participation,” Lopez said. “ISHS, which has more than 130 working groups, also holds an international congress every four years. It is open to all of its members, making for a very large scientific meeting. The 30th International Horticultural Congress is scheduled for Istanbul, Turkey, in 2018.”

Lopez said light symposium attendees made up a very diverse group that included scientists, researchers, graduate students, growers and members of various companies which helped sponsor the event.

“There are two ISHS conferences that I typically attend, this light symposium and the International Symposium on New Ornamental Crops,” he said. “The ornamentals symposium attracts more people because ornamentals and floriculture are more general than lighting. Lighting is more specific to certain countries and northern latitudes or to places that are just now starting to produce plants indoors. This would include primarily Europe, the U.S., Canada, Korea and Japan. These were the countries that had the most participants at the light symposium. In terms of the number of oral and poster sessions, there were an equal number of researchers focused on ornamentals and vegetables.”

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Horticulture industry steps up

Lopez said planning the light symposium and preparing the written proceedings that accompany it are very time consuming.

“There is a lot of speculation as to what the conference is going to cost and how many people are going to attend,” he said. “As hosts we take on the financial burden because we really don’t know what the attendance will be. Erik and I anticipated 200-300 participants based on the previous symposium that was held in the Netherlands in 2012.”

Lopez said they received financial support from 25 industry companies.

“There were different categories of sponsorship, including three prime sponsors for the symposium’s opening reception, banquet and tours. There were three additional levels of sponsorship, platinum, gold and silver. Sponsoring companies included many of the leading plant light companies, plant breeding companies, distributors, an industry association and the trade press.

“The sponsors were recognized on the light symposium’s website, as well as banners that were hung in different locations during the symposium. The sponsors received a lot of exposure and those at the prime and platinum levels had vendor booths that featured product information and samples. Because of the sponsors’ financial support, we were able to lower the cost of the registration fee for attendees. We were also able to subsidize the graduate student registration cost.”

There were 35 graduate students who presented both oral and poster sessions. The students came from several different countries.

“We also had a graduate student poster competition,” Lopez said. “Three winners were awarded. There were three judges, all representatives from academia in the U.S., Europe and Japan. The poster winners were awarded certificates and monetary awards provided by a sponsor company.”

Organizing the presentations

Lopez said he and Runkle began accepting abstracts from potential symposium presenters in Feb. 2015.

“There is a scientific committee that consists of 39 people, most of whom have a PhD. or are working toward a PhD.,” he said. “Over 90 percent of the committee members are from academia, but there are also industry members.

“We had a call for abstracts so people would submit an abstract based on the research they wanted to present. Participants who submitted abstracts indicated whether they wanted to do an oral or poster presentation. The scientific committee members reviewed the abstracts. Often times we had to send them back because there was definitely a language barrier in some cases. Often times some researchers needed help with the English translation. A lot of the researchers wanted to do oral presentations, but unfortunately there wasn’t enough time during the symposium.”

Lopez said committee members decided that some of the abstracts were more appropriate as posters than as oral presentations. There were 52 oral presentations and 78 poster presentations.

“We created 11 different oral sessions and within those sessions we tried our best to place the presentations appropriately under those titles,” he said. “The largest session was on light quality and optimization. There were an equal number of U.S. and European presenters in that session.

“The next largest session was supplemental lighting of vegetable crops. That one had research presenters mostly from Canada and Europe. No U.S. researchers did presentations in that session. Light for ornamental crops and sole-source lighting of vegetable crops were the next largest sessions.”

In addition to organizing the symposium presentations, Lopez and Runkle along with Iowa State University horticulture professor Chris Currey were co-editors of the Acta Horticulturae publication, “Proceedings of the VIII International Symposium on Light in Horticulture”.

“The majority of presentations published in the proceedings are the oral ones with a few of the poster presentations,” Lopez said. “We did request everyone who was going to do an oral presentation to write a manuscript. There were also some people who were doing posters that also submitted manuscripts. These were peer reviewed by the scientific committee.”

The Acta Horticulturae light symposium proceedings are available on the ISHS website for 105 euros.

Along with the researchers who did oral presentations there were four invited speakers, two from the United States, one from the Netherlands and one from New Zealand.

“The invited speaker presentations were longer and spurred a lot of conversation,” Lopez said. “The invited speakers started off specific topic sessions. They would give an overview of that session and then the presenters would go into their research talks.

“The invited speakers discussed future approaches to better understanding of light quality on plant growth and development. Others talked about UV light and horticulture. Kevin Folta from the University of Florida, who was one of the invited speakers, discussed how to control the light spectrum to manipulate plant responses such as growth, flavor and pigmentation.”

The next ISHS Light Symposium is tentatively scheduled for June 2020 in Alnarp, Sweden, and will be organized by the Swedish University of Agricultural Sciences.

For more:  Roberto Lopez, Michigan State University, Department of Horticulture, East Lansing, MI 48824;
(517) 353-0342;
rglopez@msu.edu;
http://www.hrt.msu.edu/people/dr_roberto_lopez

Erik Runkle, Michigan State University, Department of Horticulture,
East Lansing, MI 48824;
(517) 353-0350;
runkleer@msu.edu;
http://www.hrt.msu.edu/people/dr_erik_runkle

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

The cover photo (taken by Joshua Craver) of the January issue of the Journal of the American Society for Horticultural Science features microgreens.

Microgreens are a specialty horticulture crop consisting of vegetables and herbs harvested and consumed during the fully-expanded cotyledon or first true leaf developmental stages. Mustard (right) and mizuna (left) microgreens were grown under sole-source lighting using light-emitting diode (LED) arrays with a light ratio (%) of red:green:blue 74:18:8 (R74:G18:B8). See the paper by Craver et al.

Light Intensity and Light Quality from Sole-source Light-emitting Diodes Impact Phytochemical Concentrations within Brassica Microgreens

Abstract

By Joshua K. Craver, Joshua R. Gerovac, Roberto G. Lopez, and Dean A. Kopsell

Multilayer vertical production systems using sole-source (SS) light-emitting diodes (LEDs) can be an alternative to more traditional methods of microgreens production. One significant benefit of using LEDs is the ability to select light qualities that have beneficial impacts on plant morphology and the synthesis of health-promoting phytochemicals. Therefore, the objective of this study was to quantify the impacts of SS LEDs of different light qualities and intensities on the phytochemical content of brassica (Brassica sp.) microgreens. Specifically, phytochemical measurements included 1) total anthocyanins, 2) total and individual carotenoids, 3) total and individual chlorophylls, and 4) total phenolics. Kohlrabi (Brassica oleracea var. gongylodes), mustard (Brassica juncea ‘Garnet Giant’), and mizuna (Brassica rapa var. japonica) were grown in hydroponic tray systems placed on multilayer shelves in a walk-in growth chamber. A daily light integral (DLI) of 6, 12, or 18 mol·m⁻²·d⁻¹ was achieved from SS LED arrays with light ratios (percent) of red:blue 87:13 (R₈₇:B₁₃), red:far-red:blue 84:7:9 (R₈₄:FR₇:B₉), or red:green:blue 74:18:8 (R₇₄:G₁₈:B₈) with a total photon flux from 400 to 800 nm of 105, 210, or 315 µmol·m⁻²·s^–1 for 16 hours, respectively. Phytochemical measurements were collected using spectrophotometry and high-performance liquid chromatography (HPLC). Regardless of light quality, total carotenoids were significantly lower under increasing light intensities for mizuna and mustard microgreens. In addition, light quality affected total integrated chlorophyll with higher values observed under the light ratio of R₈₇:B₁₃ compared with R₈₄:FR₇:B₉and R₇₄:G₁₈:B₈ for kohlrabi and mustard microgreens, respectively. For kohlrabi, with increasing light intensities, the total concentration of anthocyanins was greater compared with those grown under lower light intensities. In addition, for kohlrabi, the light ratios of R₈₇:B₁₃ or R₈₄:FR₇:B₉ produced significantly higher anthocyanin concentrations compared with the light ratio of R₇₄:G₁₈:B₈ under a light intensity of 315 µmol·m⁻²·s⁻¹. Light quality also influenced the total phenolic concentration of kohlrabi microgreens, with significantly greater levels for the light ratio of R₈₄:FR₇:B₉ compared with R₇₄:G₁₈:B₈ under a light intensity of 105 µmol·m⁻²·s⁻¹. However, the impact of light intensity on total phenolic concentration of kohlrabi was not significant. The results from this study provide further insight into the selection of light qualities and intensities using SS LEDs to achieve preferred phytochemical content of brassica microgreens.

This paper was published in the Journal of the American Society for Horticultural Science.

Dr. Roberto Lopez presented some data from this study in the video below, which documented his seminar at Cornell University in 2014.

His new area of research at MSU will include hydroponic greenhouse and indoor production of leafy greens and vegetables. Roberto will also add to MSU’s horticulture curriculum by offering courses in greenhouse structures and management, floriculture production, and hydroponic food production. As part of his extension appointment, he will become the newest member of the MSU Greenhouse/Floriculture Crop Production Team which serves the $480 million dollar Michigan Greenhouse Industry (3^rd largest in the U.S). The nine member team is composed of extension educators and outreach specialists with responsibilities in commercial floriculture and controlled environment production, staff at Diagnostic Services, and faculty members in the Departments of Horticulture, Entomology, and Plant, Soil, and Microbial Sciences (http://flor.hrt.msu.edu/members/ and http://msue.anr.msu.edu/topic/info/floriculture). Roberto will continue being a member of the award winning Electronic Growers Resources Online (e-GRO) which he and his colleagues Drs. Brian Whipker, Brian Krug, and Nora Catlin, began in 2012.  Roberto comes to MSU after 8.5 years as an assistant and associate professor and Floriculture Extension Specialist in the Department of Horticulture and Landscape Architecture at Purdue University.