Brief Summary of Minutes of Annual Meeting

Brief Summary of the Minutes of the 2021 NCERA-101 Business Meeting

November 15, 2021

Start 1:00 pm

Attendance list from this conference (see above) – 146 attendees

Introduction of Executive Officers

Chair: Neil Yorio (NKOM Scientific Corporation), Vice-Chair: Murat Kacira (University of Arizona), Secretary: Marc Theroux (BioChambers), Past-Chair: Mark Lefsrud (McGill University)

Approval of Minutes

Minutes of meeting 2019 – Presented by Murat Kacira

Motion to Pass – Neil Yorio

Second – Gary Stutte

Passed unanimously

Other Conferences

• ISHS International Horticultural Congress (https://www.ihc2022.org/), Angers, France, August 14-20, 2022, Symposia S6 Innovative Technologies and Production Strategies for Sustainable Controlled Environment Horticulture and Symposia S8 Advances in Vertical Farming
• ASHS Annual Conference (https://ashs.org/page/GeneralConference), Chicago, Illinois, July 30 – August 3, 2022
• Indoor Ag Con (https://indoor.ag/), Las Vegas, Nevada, February 28 – March 1, 2022
• ASABE Annual International Meeting (https://www.asabemeetings.org/), Houston, Texas, July 17-20, 2022

Administration Advisors Report – Ramesh Kanwar

• Thanks members for participation with approximately 150 registered for the conference and 83 in attendance for the business meeting
• NCERA-101 project successfully renewed for an additional 5 years until 2026
• Station reports and meeting minutes to be submitted in the NIMSS system within 60 days after this meeting (due before January 14, 2022)
• Encouraged the group to pursue oversees meeting and to explore funding
• Encouraged the NCERA-101 committee to re-apply for a Research Excellence award by the USDA. In the application include that the committee started in 1972, has a growing membership, diversity of membership (USDA, NIFA, Universities, NASA, Industry, multi-Country membership), and highlight the projects which were funded at a multi-State and multi-University level.

USDA/NIFA Representative Report – Brad Rein

• Brad is the National Science Liaison for Sustainable Ag., Technology, Economics & Social Sciences
• Longest serving NIFA employee
• Present programs he is responsible for include Urban, Indoor & Emerging Ag. and 5 Hatch Multi-State (Micro-irrigation, Safety, Sustain. Systems Env. Hort.)
• Urban, Indoor, and Emerging Agriculture (UIE) is a new authorization from the farm bill and Brad is the lead to get the program started
• Mandatory funding of $10 million and authorized up to $10 million for each fiscal year FY19-FY23
• Working on getting ready for Request for Applications
• https://nifa.usda.gov/program/uie-ag
• Steven Thomson is the liaison for the NCERA-101

Website Report – Carole Saravitz

• Most visited website pages from Nov 2020 to 2021: Home page (28%), Growth Chamber Handbook page (14%), Meetings page (9%), Members page (5%), and Reporting Guidelines page (2%)
• Website visits by country: United States (39%), Canada (14%), China (9%), India (4%), Brazil (2%)
• Carole can post information and links on the website for research that is relevant to the group
• Gary Gardner recommended having a page on the website with information related to Vertical Farming and Carole responded that she could add a section on this topic and asked the group to forward her information for her to post

Membership Report – Mark Romer

• Mark collects/updates members information and works with Carole to update the members information on the website
• 46^th Annual Meeting – First time in a large format Zoom meeting
• Grateful to Erik, Roberto, and team at MSU for having organized this years meeting
• Membership Summary (see appendix A)
  • 173 Members
  • 137 Total Institutions (53 Industry Institutions)
  • 33 U.S. States
  • 9 Countries
• Passing away of three members this past year including Don Krizek (founding father of this group and active participant since 1976), AO Rule (one of the first industry members), and Ed Harwood (member since 2008, established a successful indoor farming company)
• One of the earliest controlled environment facilities, the Biotron at the University of Wisconsin has closed to plant research. Started in 1967 and the home to a founding father of this group Ted Tibbitts. It was also the first-place plants were grown with LED lights back in 1986.
• 20 Year membership awards presented to three members: Marc Theroux (member since 2001) presented by Mark Romer, Marc van Iersel (members since 2000) presented by Bruce Bugbee, and John Lea-Cox (member since 1997) presented by Marc van Iersel

Guidelines

• ASABE Standards efforts (Mark Lefsrud) 
• PAFS – 30 - X653 Recommended Practice for Heating, Ventilation and Air Conditioning (HVAC), and Lighting Systems Used for Indoor Plant Growth without sunlight. It has been accepted, joint standard with ASABE and ASHRAE, session at ASABE annual meeting to present material, now published as ANSI/ASABE/ASHRAE EP653 Heating, Ventilating, and Air Conditioning (HVAC) for Indoor Plant Environments without Sunlight.
• ES-311 - X644 Performance Criteria for Optical Radiation Devices and Systems Installed for Plant Growth and Development. On hold and is moving along.
• ES-311 - S642 Recommended Methods of Measurements and Testing for LED Radiation Products for Plant Growth and Development. Published approximately 3 years ago.
• ES-311 - S640 Definition of Metrics of Radiation for Plant Growth (Controlled Environment Horticulture) Applications. Up for renewal and new committee has been formed to potentially include the addition of ePAR.
• Bruno Faucher asked about X653 and a similar standard for greenhouses of which Mark Lefsrud indicated that there is a standard but that it is being archived as the greenhouse manufacturing society has it’s own standard
•  CEADS (Controlled Environment Agriculture Design Standards) (Gary Stutte)
• Overall sustainability rating of facilities (https://ceads.ag)
• Standard looks at crop quality, automation & labor, materials & waste, resource utilization, profitability, integrated pest management, equity & localness
• Approximately 150 different criteria used for a point based system
• Standards in development and undergoing prototyping with select number of industry participants before public release

Instrument Package and Financials Report – Bruce Bugbee

• $42,000 in the NCERA-101 “Travel” account
• Less money is being used for instruments and more towards student travel grants, student awards, and a buffer for hosting meetings
• Bruce is looking to see if the money could be placed in an interest bearing account with the University
• Consider investing more towards student awards and student travel grants

Graduate Student Update – Jonathan Frantz

• 11 speakers for student lightning talks (5 minutes each)
• Awards for 1^st, 2^nd, and 3^rd place
• Bruce Bugbee mentioned that the money for the student travel awards are provided to the student’s lab and that we should do the same for the student presentation awards as it is easier to process the payments from University to University versus a direct payment to the student, the lab could then re-imburse the students accordingly
• Neil Yorio suggested that after the meeting the executive committee discuss the amount that should be given for student presentation awards

Future Meetings

• 2022 University of Arizona (International Meeting), Murat Kacira’s team hosting
  • 11-14, 2022
  • Marriott University Park Hotel, Tucson, Arizona, USA
  • 5 days of technical sessions, tour a commercial grower on afternoon of day 3
  • Hybrid meeting with in person attendance and also with remote attendance
  • Will have poster session and lighting talks for students
• 2023 Meeting
  • Shamim Ahamed from the University of California Davis expressed interest in hosting and Melanie Yelton from Plenty offered to help
  • Leo Lobato-Kelly from Karma Verde Fresh has also expressed interest in hosting a meeting in Mexico
  • The executive committee will meet to review the two options
• 2024 Iowa State University, Chris Currey’s team hosting
• 2025 Meeting, host to be determined at a future date

Election of Secretary

• Motion to nominate Ricardo Hernandez (NC State University) by Neil Yorio
• Second Bruce Bugbee
• Passed unanimously, Congratulations to Ricardo

NCERA-101 Membership Growth – Bruce Bugbee

• As the group has grown there are some concerns with meetings losing their focus as an academic group as it is formally a multi-state working group from Ag Experiment Stations
• There have been previous discussions on separation of academic interests and commercial interests and this year the group provided 10 minutes for academic talks and 5 minutes for commercial talks
• Consider formalizing contributions to the group e.g. Gold, Silver, Bronze
• More time for academic talks and less time for commercial talks may reduce some of the insights gained from the commercial talks
• Neil Yorio discussed if presenters should submit abstracts and a committee would review the abstracts to determine if more time should be allocated
• Gary Stutte raised some concerns with having too much separation of the commercial group as they are a source for information on new innovations
• Gary Gardner mentioned that what makes the group unique is the blending of science from academia and commercial groups, consider distinguishing between new product versus scientific presentation from industry
• Erik Runkle has hesitation to abstract submissions as it can be a burden to the organizing committee and would prefer to leave the flexibility to the organizers and executive committee to determine the format which provides some variety to the yearly meetings
• Mark Romer commented that new industry members may need to be reminded that presentations are for a discussion on technology and not to promote products
• Neil Yorio indicated that this year we have three types of presentations: student lighting talks, academic presentations, and industry presentations
• Bruce Bugbee suggested that we leave it as it is and let the annual organizers determine the format but continue to be aware this issue
• Gary Gardner recommended that we further discuss this at next years meeting

New Business

• No new business items were brought forward for discussion

Passing of the Gavel

• Neil Yorio to Murat Kacira (now chair)

Adjourned 3:05pm (Neil Yorio)

Minutes respectfully submitted by Marc Theroux

Accomplishments (19 Reports)

(The complete station reports are available on the NCERA-101 website https://www.controlledenvironments.org/station-reports/)

1. New Facilities and Equipment

Purdue

For the SCRI OPtimIA project, Phytofy LED arrays were replaced with ORBITEC/Sierra Space BPSE LED arrays for close-canopy lighting (CCL) experiments. Each BPSE unit is continuously variable in height, and red, green, and blue LEDs are distributed uniformly within the array, which is important for close lamp/crop separation distances. BPSE LEDs are dimmable by waveband, which also is important for control of spectral composition. Height is adjustable ranging from 15 cm as the closet vertical distance between lamp and crop surface to 45 cm, which is the control based on commercial settings.

For the AFRI Minitron III project, a CO₂ injection sub-system was added prior to the inlet port to the crop gas-exchange cuvette. A mass-flow valve (MFV) was installed within a stream of pure CO₂ prior to injection into a bulk air stream. MFV apertures are controlled from a computer keyboard.  A CO₂ scrubbing sub-system was added to bulk airflow upstream of CO₂ injection for precise control of CO₂ concentration of cuvette inlet air. This was particularly useful for establishing CO₂ and light dose-response curves.

Kennedy Space Center

KSC continues to use Heliospectra RX30 LED lighting systems for many studies.  The fixtures provide nine, selectively dimmable LED wavelengths -- 380, 400, 420, 450, 520, 630, 660, 735 nm, and white (~5700 K).  KSC also uses four dimmable, 6500 K white LED arrays from BIOS Lighting (Melbourne, FL) and six red-green-blue BPSe arrays from SNC-ORBITEC (Madison, WI) mimicking the Veggie hardware.  KSC have also purchased 90 OSRAM PHYOFY RL lights to outfit several of their growth chambers and plant growth rooms, with the intent of eventual replacing the Heliospectra RX30 lighting fixtures.  The OSRAM Phytofy RL has selectively dimmable LED wavelengths at 385, 450, 521, 660, 730 nm and white (2700 K). KSC has installed a vertical wall growing system in one of their chambers that contains the 6 BPSe lights as well as 6 OSRAM PHYTOFY lights in 9 growth spaces for crop testing under environmental conditions relevant to the International Space Station.

Larry Koss of the KSC team completed fabrication and installation of six Environmental Test Chambers (ETC Chambers) that, when placed inside a walk-in chamber, allow for independent and precise control of a variety of environmental variables, to include CO₂, temperature, and humidity. The interior dimensions of the chambers are:  interior is 16” w x 18” d x 19” h (40.6 cm x 45.7 cm x 48.3) with a volume of 89.7 L. These latest ETC Chambers are an upgrade to a previous generation, and feature SOA LED lighting systems, a larger growth area, and greater control capabilities.

The Ohio State University

• Construction of Controlled Environment Agriculture Research Complex (CEARC) began in January 2021. This state-of-the-art research greenhouse facility will provide a platform for interdisciplinary research at the nexus of horticulture/crop science, engineering, entomology, plant pathology, food science, computer science, and human nutrition/health. The $36 million project is located at Waterman Agricultural and Natural Resources Laboratory farm and will be completed by summer 2022.
• Old 1000-W MH lamps were replaced with LED lights (GAVITA CT 1930e LEDs, 780 W) in departmental research greenhouse compartments (a total of 7,000 sqft). While electric power consumption is saved by 20%, the PPFD over bench was increased to 3 times or greater level.
• Soil moisture sensors (Meter EC-5 and TEROS-12) were installed in the strawberry troughs filled with coco-coir substrate.
• UV lights were installed over tomato plants of genotypes sensitive to intumescence-inducing UV-deficient light environment. Operation time and target intensities were selected to provide a minimum UV-B dose (300-320 nm integral: 17 mmol m^-2 d^-1) to prevent intumescence injury.
• LiDAR sensor was installed on a mobile irrigation boom to characterize plant canopy for precision variable rate liquid delivery.

Rutgers University New Jersey Agricultural Experiment Station

Rutgers conducted preliminary measurements within the canopy of a lean-and-lower tomato crop, comparing a LI-COR spherical quantum sensor (LI-193) with a combination of an upward and downward facing regular quantum sensors (LI-190R). Results showed that the spherical quantum sensor captures more radiation. The calculated DLIs were on average 1.55 higher when measured with the spherical quantum sensor compared to the DLI measured with an upward facing regular quantum sensor (n = 54, St. Dev. = 0.13). Rutgers plans to conduct additional experiments with the setup they designed.

University of Arizona

• Folium wireless environmental monitoring system from Autogrow Folium - Climate Monitoring Solution — Autogrow installed within a 107 m2 ETFE glazed greenhouse compartment is being evaluated in comparison to Campbell Scientific wired sensors for air temperature, PPFD, RH and leaf surface temperature in the production of truss tomato (Project PI Giacomelli).
• The University of Arizona received and installed 72 new LED lighting bars (Model HelioSPEC Izar, with Red, Green, Blue and FR spectrum) with drivers from Heliospectra within the vertical farm facility at CEAC (UAgFarm) as part of a collaboration within USDA-SCRI funded OptimIA project. A new controller (Hash Controller, Iluminar) was installed to control light intensity, DLIs and scheduling from the new LED lighting system. Iluminar Hash wireless sensor network measuring PPFD, air temperature, RH, VPD (calculated), CO₂ was installed in their vertical farm facility to evaluate its performance and application in research activities, and as part of educational program (PI M. Kacira).
• Graduate student KC Shasteen (advisor M. Kacira) has developed and evaluated a computer vision system with predictive modeling to monitor and evaluate crop growth and yield.

Arizona State University

• The Arizona State University (ASU) Indoor Farming Lab was launched in April, 2021. The ASU Indoor Farming Lab consists of 10 deep water culture hydroponic growing racks, each with three tiers. Each growing rack is equipped with LED lamps, a quantum sensor (LI-190R, LI-COR), and a thermocouple (Type E, Omega Engineering). Two additional fan aspirated air temperature and relative humidity probes (EE08-SS, Apogee) are used to monitor the air temperature and relative humidity in the ASU Indoor Farming Lab. All environmental data is recorded by a datalogger (CR1000X, Campbell Scientific).
• Multiparameters pH/EC/DO/Temperature (HI98194, Hannah Instruments) were purchased to measure the dissolved oxygen concentration of the hydroponic nutrient solution.
• Fan aspirated thermistors (TS-110-SS, Apogee), pyranometers (LI-200R, LI-COR), quantum sensors (LI-190R, LI-COR), and a datalogger (CR1000X, Campbell Scientific) were installed in the research greenhouse.
• Two walk-in growth chambers are installed. The growth chambers will enable experiments to investigate the effects of different temperatures, light qualities, CO₂, and relative humidity on plant growth and development.

University of California Davis

The college of agricultural and environmental sciences (CAES) at the University of California, Davis (UC Davis), has 162 greenhouses facilities with about 155,00 sq. ft of spaces. A new shipping container-type facility has recently been added for teaching and research. The controlled environment engineering lab is currently working with the vendor to add a walk-in type indoor vertical farming facility to study the energy use efficiency for indoor growing spaces.  CELPA is also working on designing a lab-scale autonomous vertical aquaponic growing system. This research facility would study the energy efficiency aspects and life-cycle assessment of vertical aquaponic systems for indoor application.

University of Delaware

The University of Delaware has completed the development of the Delaware Indoor Ag Lab (DIAL), which is housed in the Fischer Greenhouse Complex at the University of Delaware. This lab will serve as the main indoor agriculture research facility in Delaware with state-of-the-art LED technology and environmental control systems. It has three separate sections in the same room to allow for multiple simultaneous research projects:

• Two 3-tier shelving units are equipped with Osram Phytofy RL LED fixtures for indoor plant research on interactions among light quality, intensity, and duration. Each fixture has six independently programmable color channels, including ultraviolet-A, blue, green, red, far red, and warm white. The University of Arizona has installed vertical and horizontal fans to promote air movement and temperature and humidity sensors (Onset) to collect data on each shelf.
• Four 3-tier shelving units are equipped with arrays of Demegrow LED fixtures for indoor plant research on light intensity and duration. The warm-white LED fixtures are dimmable with adjustable timing through wireless smartphone control.
• Four reach-in plant growth chambers from Percival Scientific are dedicated to indoor plant research on environmental optimization. Each chamber has precise control of light, air temperature, relative humidity, and carbon dioxide concentration. Two tiers within each chamber have tunable LED arrays comprised of four independent color channels, including blue, green, red, and far red. All environmental parameters are adjustable and monitored through a touchscreen interface.

The University of Delaware has purchased a variety of instruments for plant data collection including: 1) a CIRAS-3 photosynthesis system (PP Systems); 2) a CI-202 leaf area meter (CID Bio-Science); 3) a CR-10 Plus color reader (Konica Minolta Sensing); 4) analytical and top-loading balances (A&D); 5) a Genesys 40 Vis spectrophotometer (Fisher Scientific); 6) quantum sensors and a field spectroradiometer (Apogee); 7) an MC-100 chlorophyll meter (Apogee); and 8) a forced-air drying oven (Shel Lab).

University of Georgia

Although not exactly a new facility or equipment, the University of Georgia’s department of Horticulture is pleased to welcome Dr. Rhuanito Ferrarezi as a new faculty member with a research focus in CEA. Dr. Ferrarezi’s research program will focus on CEA production systems and nutrient management. He will also teach a split-level course in greenhouse management and an undergraduate course in controlled environment agriculture.

Inspired by prior work with a commercial multi-spectral imaging system, the University of Georgia has developed a low-cost multi-spectral imaging system. The system uses a Raspberry Pi microcomputer and Arducam monochrome camera. The system takes images under red, green, blue, and infra-red light, as well as an image of chlorophyll fluorescence emitted by plants. Other colors can easily be added if desired. The Raspberry Pi automatically analyzes the images, applying a mask to separate plant from background and creates normalized difference vegetation index (NDVI) and anthocyanin content index (ACI) images. The spatial distribution of NDVI and ACI is automatically quantified. The system can be assembled for ~ $400.

Texas A&M University

• Texas A&M have installed a new shipping container with three compartments (equivalent to growth chambers) at Dallas Center.
• Texas A&M are establishing and equipping a new research laboratory in Controlled Environment Agriculture/Horticulture at College Station.

USDA-ARS (Beltsville, Maryland)

• A contract was awarded for 6 new Conviron PGC-FLEX growth chambers and 2 new walk-in BDW120 plant growth rooms to be installed in November, 2021 at the Controlled Environment Facility (CEF) located in Beltsville, Maryland. The CEF currently includes 21 actively managed growth chambers. These include 10 reach-in style EGC units equipped with HID lamps, 2 walk-in EGC units with fluorescent lamps, 7 Biochamber reach-in style units originally equipped with HID lamps, and two smaller Biochamber units with LED lamps. In response to an energy conservation push, USDA retrofitted the HID light canopies in the 7 Biochamber units with LED lamps. The new Conviron units will also be equipped with LED lamps of the same spectral quality. A set of six obsolete EGC reach-in units exceeded their life-cycle (purchased in the 1980s) and were removed from the facility. Moving forward into 2022, CEF will include 23 actively managed growth chamber units.
• Improvements related to outdoor chiller and cooling tower operations were implemented at the Soil-Plant-Atmosphere-Research (SPAR) facility. These included upgraded software systems to improve chiller control actions and new loop temperature and coolant flow sensors which together reduce energy consumption. A set 18 new LI-7000 CO₂/H₂O gas analyzers (LI-COR Biosciences) were installed to replace older style, obsolete, LI-6262 units. A new CO₂ scrubbing system was recently purchased to provide CO₂ free air to assist in maintaining desired set-points during the night-time in the SPAR chambers. The system will be integrated in 2022. In total, the SPAR facility includes 18 outdoor SPAR chamber units and six reach-in style Biochamber units with HID lamps.
• Two adjacent mini-greenhouse units which utilize forced air systems for heat were retrofit with CO₂ control along with data acquisition system and sensors for measurement of photosynthetically active radiation, relative humidity, air and soil temperature, and time-domain reflectometry (TDR) soil water content data. Climate data is logged at 30 second intervals while TDR data is recorded manually per end-user control.
• A new OctoFlox rugged multi-target SIF/hyperspectral reflectance spectrometer (JB – Hyperspectral) which will assist studies related to high throughput greenhouse phenotypic system related to measuring SIF (solar induced fluorescence) and reflectance. A Pika L hyperspectral camera (Resonon) was also purchased for this phenotyping work along with a RSE 600 (Fluke) thermal imaging camera.

Sierra Space

Sierra Space is in  the process of testing the Astro Garden® test facility (Figure 1). The Astro Garden is a testbed for vegetable crop production in space habitations. The system has approximately 5.4 m² of growing area and most of the subsystems are designed to be gravity independent for operation. The testbed provides temperature, humidity, CO₂ control, and nutrient solution control. Root zones currently use aeroponics but are modular so alternative technologies can be tested. Lighting is provided by red, blue and white LEDs. Each module has individual control of light level, photoperiod and light quality. The system also has a mechanism for capturing transpired water. Astro Garden was configured to meet the NASA Exploration Life Support Salad Crop Diet production requirements.

LI-COR BioSciences

• The new LI-600 Porometer/Fluorometer is a lightweight, handheld porometer and optional fluorometer that simultaneously measures stomatal conductance and chlorophyll fluorescence of leaves while they are connected to the plant.
• The LI-6800 Portable Photosynthesis System characterizes gas exchange and fluorescence and numerous other parameters under controlled chamber conditions of light, temperature, humidity and CO₂.

Percival Scientific

With the help of USDA through the Rural Economic Development Loan and Grant Program, investment partners Minburn, CIPCO, the Iowa Area Development Group, City of Perry, and Perry Economic Development; Percival broke ground as part of a new expansion to the plant this year.  This will add to the production space by over 60 percent, increase Percival’s production capacity, and allow the company to focus on larger products while continuing to grow their traditional product lines.

Plenty

• In Compton, CA, Plenty is building a 95,000 ft² vertical farm with the world’s highest leafy green production capacity.
• Plenty has attracted over $500M of investment so far.
• Plenty is collaborating with Driscoll’s to grow strawberries vertically.

2. Unique Plant Responses

Purdue

Through gas-exchange analysis, baby-green and leafy-green crop stands followed the same pattern as they responded to various levels of CO₂ and light intensity in dose-response curves. Although the overall pattern was similar, leafy greens saturated at slightly higher concentration than did baby greens in CO₂ dose-response curves.

It is estimated that 68.4% of global population live in urban areas by 2050. The population growth demands regular supply of fresh, nutritious, and safe food in urban areas. One concept that has evolved recently is to produce food in urban areas using indoor vertical farming. These farms can be fitted with customized LED lights for producing leafy greens and other small-statured crops. Purdue is studying the effects of spectral composition of light ranging from 365 to 750 nm on phytochemical levels including beta-carotene (precursor to vitamin A), phylloquinone (precursor to vitamin K), and anthocyanins (anti-oxidants) in lettuce. The purpose is to understand the physiological mechanisms affected by light spectral composition that influence phytochemical levels in lettuce. Purdue’s goal is to increase nutritional value of lettuce with minimal negative effect on plant growth and quality. Purdue has established a vertical production system where air temperature, light intensity, and spectral composition are tightly controlled. In addition, Purdue has established assays to measure phytochemical levels in plant tissue.

Although there has been a double-digit increase in the demand for organic produce during the last three decades, low crop yields have been a persistent problem in organic farming. This is attributed mainly to low nitrogen (N) availability to plants and lack of synchronization between crop growth and N release from organic fertilizers. Organic yields can be improved by optimizing plant N levels. However, this requires regular monitoring and optimal management of plant N status. Purdue is developing affordable and reliable IoT sensors for capturing and locally processing images, and estimating plant growth and N status. When developed, the sensors will effectively collaborate with each other and provide automated decision support on nutrient delivery to plants and managing optimal N status in plants. Currently, Purdue is manually studying different organic recipes for lettuce that result in crop yields which are comparable to conventional hydroponic production. Purdue will test the efficacy of the IoT sensor technology to automatically maintain high lettuce yields and optimize fertilizer use in organic hydroponic production using the developed organic fertilizer recipe.

Water scarcity, food insecurity, under-nourishment and unemployment are major issues faced by Egypt. With population growth expected to increase by 50 million in next 20 years, there is an increased risk of food insecurity in Egypt. Research has shown that hydroponic and aeroponic production systems can save 60 to 75 percent of irrigation water and produce yields similar or better than field based production. Hydroponic/aeroponic production under protected agriculture (e.g. greenhouse) can ensure year-round food production with less water requirement in Egypt. However, region-specific hydroponic production technologies need to be developed. The technology is medium to high in investment. To develop technologies that are feasible to small-scale growers in Egypt, it is critical that they are efficient and affordable. With support from USDA FAS, Purdue is conducting research on screening best hydroponic/aeroponic technologies for Egypt. Best technologies that reduce water-use and maximize crop yield and nutritional quality will be validated in Egypt. Sustainability of new technologies in Egypt will heavily rely on developing trained workforce. Purdue’s approach is to conduct extension and outreach activities in Egypt to train producers (especially women and small-scale producers) by demonstrating the benefits of developed technology.

Kennedy Space Center

During the Veg-03I tech demo test on ISS in early 2021 the crew attempted to transplant an extra pak choi seedling into an empty plant pillow for the first time in Veggie.  The extraction of the seedling did not go as intended, most of the roots were severed (Figure 2) and the ground team had little hope the seedling would reestablish itself in its new pillow and survive until final harvest.  Much to the surprise of Kennedy Space Center researchers, the seedling survived and did quite well over the next few weeks and reached final harvest.  A second transplant was attempted during Veg-03I with ‘Red Russian’ kale and a similar phenomenon was observed.  The mechanisms are not clear right now, but microgravity appears to confer some benefit to transplanting in space.

Figure 2. Left: Pak choi seedling transplanted 10 Days after initiation. Right: Comparison at Day 28 of an original and transplanted pak choi.

McGill University

Chlorophyll’s light-harvesting role in photosynthesis has not been challenged in over 40 years. Using light emitting diodes and a high-resolution monochromator, McGill University developed a method to measure at 1-nm increments a spectral photosynthesis curve determined in tomato plants with a 10-nm bandwidth light spectrum. Minimal photosynthetic rates (mmol CO₂ m^-2 s^-1 nm^-1) were recorded at spectra corresponding to peak chlorophyll absorbance (420 nm and 660 nm for chlorophyll a, and 450 and 640 nm for chlorophyll b), showing that extracted pigment absorbance peaks and photosynthesis are inversely correlated. Photosynthesis theory decrees that photosynthetic pigments drive photosynthesis, and that these pigments absorb and convert specific wavelengths of light energy into chemical energy. McGill Universities’ finding implies that chlorophyll may carry out an additional regulatory function in photosynthesis that has not yet been identified.

The Ohio State University

• Low pH 4.0 of hydroponic nutrient solution can effectively suppress the severity of root rot caused by aphanidermatum initiated by zoospore inoculation without influencing basil plant growth. This could be a new, low-cost strategy for water-borne disease prevention in hydroponic basil production (Gillespie, 2019; Gillespie at al., 2020).
• While basil can tolerate low pH (upto 4.0), most crops exhibit growth reduction caused by reduced nutrient uptake at low pH. When tested at pH 4.5 spinach reduced the shoot fresh weight by almost 60% compared with that under a standard pH 5.5. By increasing the nutrient concentrations (3X), the shoot fresh weight was recovered but still ~25% lower than the standard pH 5.5 (Papio, 2021; Gillespie et al., 2021).
• Nine lettuce cultivars considered as relatively sensitive to tipburn were grown under tipburn inducive conditions to assess the different degrees of sensitivity among cultivar types (romaine, butterhead, and leaf), leaf color (red and green) and production systems originally targeted in breeding program (open-field and greenhouse). Greenhouse cultivars were found relatively less sensitive and exhibited lower tipburn incidences than did open-field cultivators when grown under tipburn inducive indoor growing conditions. Cultivar-type did not show a significant effect on tipburn sensitivity. (Ertle and Kubota, unpublished).
• Reciprocal grafts between two cultivars – ‘Nufar’ (NF), a vigorous and Fusarium wilt resistant cultivar, and ‘Dolce Fresca’ (DF) a compact & uniform type, were evaluated for impact of scion and rootstock on the plant growth and mineral nutrient uptake. While low vigor DF used as rootstock reduced the overall growth of NF, high vigor NF used as rootstock did not increase the overall growth. When NF was used as rootstock, plants developed relatively low biomass in roots suggesting a greater efficiency of nutrient and water uptake for NF. Basil is known to have low mineral nutrient requirement in hydroponics, which may be a reason why improved mineral nutrition did not induce greater vigor or biomass. Therefore, in addition to basil, similar studies were initiated for tomato cultivars and rootstocks in order to better understand underline mechanism of rootstock- or scion-specific mineral nutrition affecting grafting vigor in tomato (Hollick and Kubota, 2021).

University of Delaware

Undergraduate student Stefanie Severin and Qingwu Meng investigated how alternate light intensities at 12-h intervals influenced indoor tomato, lettuce, and arugula seedling growth. Experimental results indicated that the effects of the daily light integral depended on the allocation of light over time and crop type. Doubling the daily light integral increased shoot mass of arugula but did not affect that of lettuce.

University of Georgia

Chlorophyll Fluorescence Imaging: A Novel, Simple and Non-Destructive Method for Canopy Size Imaging

Non-destructive methods to quantify crop growth can provide a valuable tool in both research and production settings. Quantifying canopy size can be done using a variety of imaging techniques, with regular color (red/green/blue, RGB) imaging being the most common approach. However, separating canopy from background is not always easy using RGB imaging and different methods may be needed depending on the background in the image or the color of the leaves. To circumvent this issue, the University of Georgia developed an imaging approach that takes advantage to the fluorescence emitted by chlorophyll. The energy of about 1 to 3% of photons absorbed by leaves is re-emitted as photons in the range of ~690 to 740 nm. This fluorescence coming from plants is easy to photograph: plants are exposed to blue light and images are taken using a monochrome camera with a 680 nm long-pass filter (i.e., only photons with wavelengths > 680 nm can pass through the filter). This assures that the camera can only detect fluorescence from chlorophyll. One complication is that the chlorophyll in algae fluoresces similar to that in plants, so image processing may be needed to separate algae from leaves. This can be achieved by comparing images collected under both blue and white light: algae are more pronounced under blue than under white light. Alternatively, algicides have proven effective in suppressing algae without harmful effects on plants. Comparisons of leaf area measurements using the fluorescence imaging versus a leaf area meter indicate that the fluorescence imaging is almost perfectly correlated with standard leaf area measurements (R² = 0.998). Chlorophyll fluorescence imaging can also be used to monitor ripening of fruits that contain chlorophyll in their unripe state. The decrease in fruit chlorophyll levels during ripening is easily quantified using this approach. The hardware costs for a chlorophyll imaging system are ~$1,000 and the system is easy to assemble. Researchers: Mangalam Narayanan, Marc van Iersel, Mark Haidekker.

Light Intensity Affects Leaf-Level and Crop-Level Water Use Efficiency

The cost of dehumidification is a significant portion of the total production costs in indoor production systems. Minimizing this cost can be achieved by maximizing the water use efficiency of the plants, thus reducing the need for dehumidification. This study was performed to determine leaf- and crop-level water use efficiency of vegetative and flowering crops under various photosynthetic photon flux densities (PPFD). ‘Purple Wave Classic’ petunia and ‘Green Salad Bowl’ lettuce were grown in a walk-in growth chamber, under PPFDs ranging from 152 - 374 µmol·m^-2·s^-1_, provided by white LED lighting. To achieve the same daily light integral (DLI) of 12 mol·m^-2·d^-1, photoperiods ranged from 21.6 to 9 h in the different treatments. The temperature in the growth chamber was 24 °C and CO₂ was maintained at 800 ppm. Leaf-level assimilation increased with increasing PPFD in petunias and lettuce. However, in petunias transpiration decreased with increasing PPFD, whereas in lettuce it increased. This led to an increase in leaf-level water use efficiency in petunias with increasing PPFD, whereas in lettuce, there was no correlation between water use efficiency and PPFD. For both lettuce and petunia, dry weight decreased with higher PPFDs provided over shorter photoperiods. Petunia biomass was 57.0% higher at 152 µmol·m^-2·s^-1 than at 374 µmol·m^-2·s^-1 and lettuce biomass was 33.9% higher at 152 µmol·m^-2·s^-1 than at 374 µmol·m^-2·s^-1, when plants were given the same DLI of 12 mol·m^-2·d^-1. In petunia, dry weight decreased more strongly with increasing PPFD than water use, and thus crop-level water use efficiency decreased with increasing PPFD (p < 0.001). For lettuce, crop-level water use efficiency also decreased with increasing PPFD (p < 0.001). In conclusion, leaf-level measurements and crop-level measurements of water use efficiency did not show the same trends; leaf level measurement may thus provide misleading information. Crop-level measurements of plants grown under varying PPFD, but with the same DLI showed that lower light intensities and longer photoperiods resulted in higher yields and higher water use efficiency in both lettuce and petunias. Researchers: Laura Reese and Marc van Iersel.

Supplemental Far-Red Light Increases Final Yield of Indoor Lettuce Production By Boosting Light Interception at the Seedling Stage

Understanding crop responses to light spectrum is critical for optimal indoor crop production. Far-red light is of special interest, because it can accelerate crop growth both physiologically and morphologically. Far-red can increase photosynthetic efficiency when combined with lights of shorter wavelength. It also can induce leaf expansion, possibly increasing light capture and growth. However, the optimal amount of supplemental far-red light for crop growth and yield in indoor lettuce production is yet to be quantified. Lettuce ‘Cherokee’, ‘Green Salad Bowl’, and ‘Little Gem’ were grown under 200 µmol·m^-2·s^-1 warm white LED light with 16 levels of additional far-red light, ranging from 0 to 76 µmol·m^-2·s^-1. Supplemental far-red light increased canopy light interception (a measure of canopy size) 6 days after far-red light treatment for ‘Green Salad Bowl’ and ‘Little Gem’ and after 8 days for ‘Cherokee’. The enhancement in canopy size was no longer evident after 12 and 16 days of far-red treatment for ‘Green Salad Bowl’ and ‘Little Gem’, respectively. The length of the longest leaf of all three cultivars was increased linearly by far-red light, consistent with a shade acclimation response to far-red light. Final dry weight of ‘Cherokee’ and ‘Little Gem’ were increased linearly by far-red light when harvested 20 days after the start of far-red light treatment, but dry weight of ‘Green Salad Bowl’ was not affected. In conclusion, adding far-red light in indoor production gives lettuce seedlings a jumpstart at capturing light. Supplemental far-red light increases crop yield linearly up to 76 µmol·m^-2·s^-1 in two of the three cultivars tested. Researchers: Jun Liu and Marc van Iersel.

The Quantum Requirement for CO₂ Assimilation Increases with Increasing Photosynthetic Photon Flux Density and Leaf Anthocyanin Concentration in Lettuce

The quantum requirement for CO₂ fixation, or moles of photons required to fix one mole of CO₂, determines how efficiently plants can use light to produce carbohydrates. It is calculated as the amount of absorbed light (photosynthetic photon flux density (PPFD) × leaf absorptance) divided by gross photosynthesis. Due to the high lighting costs in controlled environment agriculture, a low quantum requirement may increase growth and profitability. Typical estimates of the quantum requirement (~10-12 mol·mol^-1) are based on the initial slope of photosynthesis-light response curves and do not account for non-photosynthetic pigments or changes due to light intensity. Anthocyanins, typically located in epidermal cells, are not photosynthetically active and light absorbed or reflected by them cannot be used for CO₂ assimilation. Since anthocyanins reduce how much light reaches photosynthetic pigments, anthocyanin-rich lettuce cultivars may have a greater quantum requirement than green cultivars. Additionally, photosynthetic light-use-efficiency decreases with increasing PPFD. The University of Georgia hypothesized that both higher anthocyanin levels in lettuce and increasing PPFD would increase the quantum requirement and quantified this using six red and three green lettuce cultivars, having a wide range of anthocyanin concentrations. Lettuce was grown in a greenhouse without supplemental lighting. The environmental conditions were a temperature of 25.2 ± 3.2 °C, a vapor pressure deficit of 1.0 ± 0.5 kPa, and a daily light integral of 24.2 ± 6.3 mol·m^-2·d^-1 (mean ± SD). Leaf-level photosynthesis was measured at PPFDs of 0, 50, 100, 200, 400, 700, 1000, and 1500 µmol·m^-2·s^-1. An integrating sphere was used to measure leaf absorptance. Anthocyanin concentration of the lettuces ranged from 12 to 71 mg·m^-2. Absorptance increased linearly from 0.77 to 0.87 with increasing anthocyanin levels (R² = 0.72, P < 0.001). Gross photosynthesis at a PPFD of 1500 µmol·m^-2·s^-1 was ~50% lower in leaves with the highest anthocyanin level (8.1 µmol·m^-2·s^-1) than that of those with the lowest anthocyanin level (16.2 µmol·m^-2·s^-1) (R² = 0.32, P = 0.004). The quantum requirement for CO₂ assimilation at a PPFD of 1500 µmol·m^-2·s^-1 increased from 80 to 150 mol·mol^-1 as the anthocyanin concentration increased (R² = 0.32, P = 0.003). With PPFD increasing from 200 to 1500 µmol·m^-2·s^-1, the quantum requirement increased from 30 to 110 mol·mol^-1 (R² = 0.63, P < 0.001). In summary, both anthocyanins and high PPFD increased the quantum requirement for CO₂ assimilation to levels far above those typically cited in the literature. Researchers: Changhyeon Kim and Marc van Iersel.

Only Extreme Fluctuations in Lights Levels Reduce Lettuce Growth

The cost of providing supplemental lighting in greenhouses or sole-source lighting in plant factories can be high. In the case of variable electricity prices, it may be desirable to provide most of the light when electricity prices are relatively low. However, it is not clear how plants respond to the resulting fluctuating light levels. The University of Georgia hypothesized that plants that receive a constant photosynthetic photon flux density (PPFD) would produce the more biomass than those grown under fluctuating light levels. To quantify growth reductions caused by fluctuating light levels. The University of Georgia quantified the effects of fluctuating PPFD on the photosynthetic physiology and growth of ‘Little Gem’ and ‘Green Salad Bowl’ lettuce. Plants were grown in a walk-in growth chamber outfitted with three shelving units, each divided into six growing compartments. Each compartment contained two dimmable, white LED bars, programmed to alternate between high and low PPFDs every 15 minute. The PPFDs in the different treatments were ~ 400/0, 360/40, 320/80, 280/120, 240/160, and 200/200 µmol·m^-2·s^-1, with a photoperiod of 16 hours and a DLI of ~11.5 mol·m^-2·d^-1 in all treatments. CO₂ was maintained at ~ 800 µmol·mol^-1. Data was analyzed using linear and non-linear regression. At 400/0 µmol·m^-2·s^-1, 30-minute-integrated A_n (net photosynthesis integrated 15 minute at high and 15 minute at low PPFD) was ~65% lower than at a PPFD of 320/80 µmol·m^-2·s^-1 (or treatments with smaller PPFD fluctuations). 30-minute-integrated A_n in the four treatments with the smallest PPFD fluctuations (320/80 to 200/200 µmol·m^-2·s^-1) was similar. Plants grown at 400/0 µmol·m^-2·s^-1 also had fewer leaves and lower chlorophyll content compared to those in all other treatments. The four treatments with the smallest fluctuations in PPFD produced plants with similar numbers of leaves, chlorophyll content, specific leaf area, dry mass, and leaf area. Chlorophyll content, 30-minute-integrated A_n, and dry mass were positively correlated with each other. These results show that lettuce tolerates a wide range of fluctuating PPFD without negative effects on growth and development. However, when fluctuations in PPFD are extreme (400/0 or 360/40 µmol·m^-2·s^-1), chlorophyll levels are low, which can explain the low 30-minute-integrated A_n and poor growth in these two treatments. The ability of lettuce to tolerate a wide range of fluctuating light levels suggests that it may be possible to adjust the PPFD in response to variable pricing. Researchers: Ruqayah Bhuiyan and Marc van Iersel.

Chlorophyll Fluorescence Imaging: A Novel, Low-Cost Method for Early Stress Detection

Using non-destructive methods, like chlorophyll fluorescence imaging, to provide early stress detection in plants could augment growing methods and allow for corrective measures to minimize damage to the plants. While many chlorophyll fluorescence imaging techniques require expensive, sophisticated equipment while other techniques only take single-point measurements, the current study focuses on a scalable novel technique that provides whole plant digital images of the chlorophyll fluorescence (but not Φ_PSII) using blue excitation light, a monochrome camera, and a long-pass filter (> 690 nm). There are three fates of light once a photon has been absorbed by a plant: it can be used to drive photochemistry (electron transport), be converted to heat, or be reemitted as chlorophyll fluorescence. A decrease in photochemistry by stressors will typically lead to an increase in chlorophyll fluorescence and/or heat dissipation to prevent damage from excess light. Due to this relationship, chlorophyll fluorescence has been used to non-destructively diagnose the photosynthetic performance of plants, with the quantum yield of photosystem II (Φ_PSII) being a common indicator of photochemical efficiency. To test the performance of the system, a photosystem II-inhibiting herbicide was applied as a drench at standard field rates to lettuce (Lactuca sativa), impatiens (Impatiens hawkeri) and vinca (Catharanthus roseus). Chlorophyll fluorescence images were taken using the TopView Multispectral Digital Imaging System (Aris, Eindhoven, Netherlands), which also took regular RGB images. The combined reflectance and fluorescence from the leaf were measured using a spectrometer and Φ_PSII was measured using a chlorophyll fluorometer. These measurements were taken every 15 minutes for 8 hours. In between measurements, the plants were exposed to a photosynthetic photon flux density of 176 µmol·m^-2·s^-1 provided by white LEDs. The pixel intensity in the fluorescence image, a measure of chlorophyll fluorescence, was negatively correlated with Φ_PSII (P < 0.01) as measured using a fluorometer. The average reflectance in the spectral range of fluorescence (670 – 760 nm) was positively correlated with the pixel intensity (P < 0.0001) and negatively correlated with Φ_PSII (P ≤ 0.07). The results suggest that the novel chlorophyll fluorescence imaging technique is a reliable way to inexpensively detect stress to photosystem II before visible damage occurs to the plant. Researchers: Reeve Legendre and Marc van Iersel.

Supplemental Far-Red Light Does Not Increase Growth of Greenhouse-Grown Lettuce

The positive effects of far-red (FR) light on growth of leafy greens have been well-documented for crops grown in plant factories. However, there is a lack of information on the effects of supplemental FR on greenhouse-grown leafy greens. Therefore, the University of Georgia conducted a study with two cultivars of lettuce (Lactuca sativa, ‘Green Salad Bowl’ and ‘Cherokee’) with five lighting treatments. The treatments were supplemental lighting with a photosynthetic photon flux density (PPFD) of 200 μmol∙m^-2∙s^-1, PPFD of 200 μmol∙m^-2∙s^-1 + 10 μmol∙m^-2∙s^-1 of FR light, PPFD of 200 μmol∙m^-2∙s^-1 + 20 μmol∙m^-2∙s^-1 of FR light, PPFD of 220 μmol∙m^-2∙s^-1, and sunlight only. Supplemental PPFD was provided with 75% red and 25% blue light for 4 hours before sunrise and 4 hours after sunset. The daily light integral (DLI) received from the sun averaged 7.5 mol∙m^-2∙d^-1 during the study period. The treatments with supplemental PPFDs of 200 and 220 μmol∙m^-2∙s^-1 averaged DLIs of 13.3 and DLI of 13.8 mol∙m^-2∙d^-1. The FR treatments with 10 and 20 μmol∙m^-2∙s^-1 received 0.29 and 0.58 mol∙m^-2∙d^-1 of supplemental FR light. All supplemental lighting treatments increased leaf area and plant dry weight compared to the treatment without supplemental lighting (P < 0.0001). However, the University of Georgia did not see any positive effects on crop growth by adding FR light. Similarly, the treatment with slightly higher PPFD level of 220 μmol∙m^-2∙s^-1 did not show a significant growth difference compared to the treatment with a supplemental PPFD of 200 μmol∙m^-2∙s^-1. These results do not provide any evidence for positive effects of supplemental FR light on greenhouse-grown lettuce. This may be due to the presence of high levels of FR light from the sun in the greenhouses. Researchers: T.C. Jayalath and Marc van Iersel.

Development and Implementation of a New Optimal Supplemental Lighting Control Strategy in Greenhouses

The use of supplemental lighting is an effective way for increasing greenhouse productivity. Recently, using light-emitting diodes (LEDs), capable of precise and quick dimmability, has increased in greenhouses. However, electricity cost of lighting can be significant, and hence, it is necessary to find optimal lighting strategies to minimize supplemental lighting costs. The University of Georgia has modeled supplemental lighting in a greenhouse equipped with LEDs as a constrained optimization problem, with the aim of minimizing electricity costs of artificial lighting. The University of Georgia considers not only plant daily light integral (DLI) need during its photoperiod but also sunlight prediction and variable electricity pricing in this model. The University of Georgia uses Markov chain to predict sunlight irradiance throughout the day. By considering sunlight prediction information, the system avoids supplying more light than plants require. Therefore, this lighting strategy supplies sufficient light for plant growth while minimizing electricity costs during the day. The University of Georgia propose an algorithm to find optimal supplemental lighting strategy and evaluate its performance through exhaustive simulation studies using a whole year data and compare it to a heuristic method, which aims to supply a fixed photosynthetic photon flux density (PPFD) to plants at each time-step during the day. The University of Georgia also implemented this proposed lighting strategy on Raspberry Pi using Python programming language. This prediction-based lighting approach shows (on average) about 40% electricity cost reduction compared to the heuristic method throughout the year. The University of Georgia will test this approach in their research greenhouse in the winter of 2020-2021. Researchers: Sahand Mosharafian, Shirin Afzali, Javad Mohammadpour Velni, and Marc van Iersel

USDA-ARS (Beltsville, Maryland)

• Grain chalk expression from a U.S. rice hybrid variety was observed to increase as much as 40% in response to short-term heat stress (+4 or +8°C above the 28/23°C setpoint thermoperiod) applied for 14 days during grain filling. Grain fill percentage declined as much as 50% as a result of the extreme heat event, which in turn was associated with substantial decline in grain yield. Growth under elevated CO₂ (740 ppm) slightly compensated for negative heat impacts on yield, but may have exacerbated chalk expression which negatively impacts grain quality.  Research was conducted in six SPAR Daylit chambers.
• An experiment was conducted to evaluate the response of Parthenium, an invasive species, to CO₂ concentrations using two walk-in Biochamber growth cabinets. The weed was observed to grow faster and produce more parthenin (which reduces productivity of crop fields and pastures and is a cause of dermatitis in humans) with rising CO₂ levels as compared to a non-invasive biotype. This suggested that the current levels of CO₂ contributed to the plant’s global invasiveness and toxicity. This information will allow for assessing better weed control strategies and provides ecological information on subspecies variation.

Sierra Space

Hybrid Life Support Systems- Plant Culture Units

Sierra Space is continuing work on the development of Exploration Life Support Salad Crop production as an early stage implementation of hybrid life support systems (combination of bioregenerative and physical-chemical life support technologies).  Current efforts include development of aeroponic and nutrient film hydroponic (soilless) systems and variable plant spacing systems for use in the space environment. This continues efforts to develop advanced subsystems (e.g. LED lighting, porous interface transpiration recovery) that significantly reduce the mass, power, and volume of microgravity plant production.

Current efforts included a series of parabolic flights investigating aeroponic and nutrient film systems for use in microgravity, and a technology demonstration experiment for the ISS  called the Exposed Roots On Orbit Test System (XROOTS) to look at these same parameters in long duration microgravity. Sierra Space is preparing the XROOTS payload for flight in early 2022.

Space Biology

Sierra Space continues to work with the Kennedy Space Center to support the two Veggie plant growth systems and the Mass Measurement Device (for support of animal and plant sciences) currently operating on the ISS (Figure 3). 

The Advanced Plant Habitat (APH) that Sierra Space fabricated for the Kennedy Space Center is operating on the ISS to support a wide range of microgravity plant research.  This system is the largest plant growth system put in space to date. Sierra Space is currently providing engineering support to APH as it continues operations on the ISS (Figure 4). 

LIFE^TM (Large Integrated Flexible Environment) Habitat

Sierra Space continues to work with commercial partners for development of human Life Support and Thermal Control systems for space habitats. Sierra Space has moved their full-scale mockup of its LIFE module (shown in Figure 5) to NASA Kennedy Space Center.  This system is being designed to support a 1,100-day mission and is currently part of an effort to develop a large commercial space station (Figure 6).

JR Peters

Through conversations and experience working with ornamental and cannabis growers, anecdotal reports indicate that plants grown under LED lights benefit by increasing fertilizer application rates by 25-50% compared to plants grown under HPS and MH (indoor and greenhouse).

3. Accomplishment Summaries:

Purdue

For the OptimIA project, CCL tended to capture more photons that otherwise would be lost by typical 120 to 130 degree beam spread outside the cropping area below LED fixtures. Use of white curtains helped to reflect back some photons that otherwise would be would be lost. Combining CCL and reflective curtains kept or retrieved the most light, and plants either grew more or saved more energy for lighting, depending on the CCL strategy being tested.

For Minitron III, crop gas-exchange measurements indicated that photosynthesis of baby and leafy greens saturates at CO₂ levels about half of what commercial growers use, and the low light level growers use likely is why they do not get more response to their elevated CO₂.

Kennedy Space Center

A series of Veggie tech demo tests were completed in early 2021 that introduced varying amounts of crew autonomy to plant care operations.  Veg-03I grew a variety of leafy greens (Red Russian kale, Dragoon lettuce, Wasabi mustard, Extra Dwarf pak choi, and Outredgeous red romaine lettuce) alongside Veg-03J (Outredgeous romaine lettuce), the first on-orbit test of a seed film technology developed at KSC that enables astronauts to plant seeds on-orbit.  Veg-03K (Amara mustard first flight) and Veg-03L (Extra Wwarf pak choi) occurred immediately following Veg-03I/J, and featured the first example of fully autonomous crew growing of crops in space; the crew decided watering amounts and frequency, harvest dates, and other horticultural considerations independent of the ground team.

A technical demonstration in the Advanced Plant Habitat (APH) on ISS will end in November 2021 that is growing cv. Espanola Improved chile (chili) peppers for a period of 137 days.  This test will assess the capabilities of APH to conduct long-duration plant growth operations and the nutritional and microbiological differences that arise in chile peppers grown in microgravity.  The crew will consume a portion of the fruit and perform behavioral health surveys to assess the impacts of growing crops in space. The first pepper harvest was conducted on Day 109 and received considerable media attention. This project is being conducted by Matt Romeyn, LaShelle Spencer, Oscar Monje, Jacob Torres, Jeff Richards, Lucie Poulet, Ray Wheeler, and Nicole Dufour.

Gioia Massa continues work on 3-yr NASA grant to grow dwarf tomato in Veggie for the first time.  Ray Wheeler, Mary Hummerick, Matt Romeyn, LaShelle Spencer, and Jess Bunchek at KSC, Bob Morrow at Sierra Nevada, and Cary Mitchell at Purdue are Co-Is on the grant along with several Co-Is from Johnson Space Center focusing on food and behavioral health.  The focus of this research is to assess fertilizer and light quality impacts on crop growth, nutrient content, and organoleptic appeal. KSC has worked closely with Florikan Inc. to assess different controlled release (CR) fertilizer combinations. Two sets of mizuna were grown in Veggie plant pillows, one for 35 days and the second for 60 days with repetitive harvesting under both red-rich (ratio of 9:1:1 Red: Blue: Green) and blue-rich (ratio of 5:5:1 Red: Blue: Green) LED light.

The team at KSC continues work in partnership with Moon Kim and his team at USDA ARS-Beltsville on advanced plant imaging technologies for use in spaceflight.  The focus of this work has been on developing hyperspectral imaging technologies and a database of plant responses relevant to spaceflight, such as drought, over-watering, and pathogenic fungus.  The goal is to create a monitoring system able to recognize stressors early enough to take swift corrective action, and eventually, being the eyes of an autonomous plant growth system.

Figure 7. Left: Development of vegetation indices for integration with AI. Right: Hyperspectral camera scanning plants at Kennedy Space Center.

Gioia Massa was awarded a 3-yr NASA grant to study the impacts of watering on the plant microbiome in microgravity using the Advanced Plant Habitat (APH) on ISS.  Plants will be grown under four different substrate moisture scenarios to assess impacts to plant growth of chronic and intermittent substrate moisture conditions.  The microbiomes of the different treatments will be cataloged and assessed for impacts on food safety and other impacts of interest.

A one-year legume screening study was completed, with 26 cultivars of multiple pea and bean (others?) being screened and 8 promising candidates down-selected for further growth studies, and nutritional and organoleptic analysis, and possible inclusion in future growth demonstrations on ISS.

Multiple areas of new research and technology into microgreens are occurring at KSC.  A one-year investigation to assess the food safety metrics of microgreens is ongoing, this is a necessary step to clear the way for microgreens testing and consumption on ISS.  A study into novel microgreens is also underway to identify microgreen types that are sources of calories, fats, protein, and thiamine; some of the cultivars in this investigation include cantaloupe, sunflower, quinoa, and many types of legumes. NASA Postdoctoral Fellow Lucie Poulet received a one-year award to conduct parabolic flight testing of different microgreen techniques and technologies to enable harvesting of microgreens in microgravity.

Studies on herbs and herb microgreens continued to determine herb varieties that will grow well in a space environment to supplement packaged diets in space flight.  Sixteen herb varieties (how many species?) were tested initially in spring of 2020, and down selection of these continued based on growth, and nutrient content.  In 2021, 12 varieties of full-sized herbs and 14 varieties of herb microgreens were cultivated under spaceflight-relevant conditions and analyses of these are ongoing, with microbial and nutritional analysis underway.  Additionally, novel leafy crops such as Malabar spinach, dandelion and golden purslane have been tested, with more  crops to be studied in the coming year.

Lucie Poulet is a NASA Postdoctoral Fellow working on a project entitled “Modeling plant growth and gas exchanges in various ventilation and gravity levels.” Lucie has been using the LI-6800 to study plant leaf responses to different ventilation levels and has designed a custom chamber for the LI-6800, which will allow similar studies of entire crop plants and canopies of microgreens. Data collected will be used to calibrate and validate a plant gas exchange model in reduced gravity environments.  Lucie is also a collaborator for the PH-04 technical demonstration of chile peppers on ISS.

Christina Johnson is a NASA Postdoctoral Fellow at KSC assessing the differences between microgreens grown in unit gravity versus those grown in simulated microgravity using  clinostats and random positioning machines (3-dimensional clinostats).  She is working with a team to design a microgreens growth and imaging platform that will be used on a random positioning machine and enable testing of microgreens growth responses to different simulated gravity levels, including lunar and Martian gravity. Christina leads monthly Microgreen Chats where she brings together contacts from NASA, USDA, academia, and the private sector with interest in microgreens. Christina has also authored and co-authored multiple white papers for the “Decadal Survey” taking place right now, where NASA solicits inputs for future research areas.

Michigan State University

• Michigan State University coordinated several outreach programs that delivered unbiased, research-based information on producing plants in controlled environments, including the Michigan Greenhouse Growers Expo and the Floriculture Research Alliance annual meeting.
• Michigan State University updated the MSU Extension Floriculture & Greenhouse Crop Production website that includes MSU-authored resources on the production of plants in controlled environments.
• Research technician Annika Kohler and Roberto Lopez quantified the effects of various rates of uniconazole on stem elongation under low (2.0 mol·m^‒2d^‒1) and high (16.3 mol·m^‒2·d^‒1) daily light integrals of five succulent genera over time. Using at least 1 mg·L^‒1 of uniconazole was enough to suppress stem elongation in most succulents studied after 10 or 15 weeks but 2 mg·L^‒1 can be used for all succulents.
• S. student Caleb Spall and Roberto Lopez investigated the influence of supplemental light (SL) quality on time to harvest and finished quality of several long-day specialty cut flowers. Time to harvest under SL containing blue, red, and far-red radiation, or 100% blue radiation, was hastened compared to plants grown under high-pressure sodium or broad-spectrum LED SL. Additionally, time to harvest was delayed under 100% red SL.
• S. student Caleb Spall and Roberto Lopez investigated the influence of young- and finished-plant photoperiod on time to harvest and quality of several cut flowers. Marigold ‘Xochi’ seedlings grown under 11- to 24-h photoperiods or a 4-h night interruption and finished under 10- to 12-h days were marketable, and of comparable finished quality.
• S. student Sean Tarr and Roberto Lopez quantified the influence of day and night air temperatures (72/59, 77/64, 82/70 °F) and light intensities (150 to 300 µmol·m^-2·s^-1) on growth of red oakleaf and green butterhead lettuces ‘Rouxaï’ and ‘Rex’. Fresh mass was greatest for both cultivars under 300 µmol·m^-2·s^-1 of light and at day/night temperatures of 77/64 or 82/70 °F for ‘Rouxaï’ and 82/70 °f for ‘Rex’. However, incidence of tip burn was greater under the higher light intensity.
• S. student Sean Tarr and Roberto Lopez investigated how air temperature and CO₂ concentration (500, 800, and 1200 μmol·mol^-1) influenced growth of ‘Rouxaï’ and ‘Rex’ at a light intensity of 300 µmol·m^-2·s^-1. Fresh mass was greatest for both cultivars at day/night temperatures of 82/70 °F and CO₂ concentrations of 800 μmol·mol^-1 for ‘Rouxaï’ and both 800 and 1200 μmol·mol^-1 for ‘Rex’.
• S. student Sean Tarr and Roberto Lopez modelled the response of kale and red oakleaf and green butterhead lettuces at day and night temperatures of 52/41 to 97/86 °F. The greatest leaf unfolding of ‘Rouxaï’ and ‘Rex’ occurred at 79/70 °F. However, fresh mass of ‘Rouxaï’ and ‘Rex’ was greatest at 88/77 °F and 79/68 °F, respectively. Kale had the greatest fresh mass at 70/59 °F, but had the greatest leaf number at 97/86 °F.
• D. student Eric Stallknecht and Erik Runkle studied the effect of an experimental red-fluorescent greenhouse film that converts some of the blue and most of the green light into red light on greenhouse- and indoor-grown lettuce. On average, the experimental film decreased the average light transmission by 25% compared to an un-pigmented control film. Despite lower light transmission, lettuce yield per plant increased by 5% to 20%, depending on cultivar. Butterhead lettuce had the greatest yield increase under the experimental red-fluorescent film.
• D. st

1. Publications:

Addo, P.W., V. Desaulniers Brousseau, V. Morello, S. MacPherson, M. Paris, M. Lefsrud. 2021.

Cannabis chemistry, post-harvest processing methods and secondary metabolite profiling: A review. Industrial Crops & Products 170:113743

Adhikari, R. and K. Nemali. (2021). Whole-Plant Tissue Nitrogen Content Measurement Using

Image Analyses in Floriculture Crops. Journal of Environmental Horticulture (Accepted).

Ahamed, M. S.; Guo, H.; and Tanino, K. (2021). Cloud cover-based solar radiation models: A

review and case study. Submitted to the International Journal of Green Energy.

Barnaby, J., Kim, J., Jyostna, M., Fleisher, D., Tucker, M., Reddy, V., and Sicher, R. Varying

atmospheric CO₂ mediates the cold-induced CBF-dependent signaling pathway and freezing tolerance in Arabidopsis. 2020. International Journal of Molecular Sciences. DOI:10.3390/ijms21207616.

Berliner, A.J. et al. (2021) Towards a biomanufactory on Mars. Frontiers in Astronomy and

Space Sciences https://doi.org/10.3389/fspas.2021.711550

Both, A.J. 2021. The science and art of crop irrigation. In Ball Redbook (19^th Edition), C. Beytes

(ed.), Volume 1: Greenhouse Structures, Equipment, and Technology. Ball Publishing. pp. 64-68.

Both, A.J. 2021. Glazing: It’s what makes the greenhouse. In Ball Redbook (19^th Edition), C.

Beytes (ed.), Volume 1: Greenhouse Structures, Equipment, and Technology. Ball Publishing. pp. 26-30.6.         

Bubenheim, D., Vanessa Genovese, Edward Hard, and John D. Madsen.

Remote Sensing and Mapping of Floating Aquatic Vegetation in the Sacramento-San Joaquin River Delta. J. Aquat. Plant Manage. 59s: 46–54.

Buncheck J.M., A.B. Curry, M.R. Romeyn.  Sustained Veggie: A Continuous Food Production

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