IMPROVING THE PROFITABILITY AND SUSTAINABILITY OF INDOOR LEAFY-GREENS PRODUCTION.

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: EXTENDED
• Funding Source: OTHER GRANTS
• Reporting Frequency: Annual
• Accession No.: 1020286
• Grant No.: 2019-51181-30017
• Project No.: MICL05115
• Proposal No.: 2019-03132
• Program Code: SCRI
• Project Start Date: Sep 1, 2019
• Project End Date: Aug 31, 2024
• Grant Year: 2019

Project Director
Runkle, E.

Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824

Performing Department
HORTICULTURE

Non Technical Summary
Indoor (vertical) farming refers to crop production in fully controlled environments, usually in stacked layers, in repurposed warehouses or shipping containers. This type of farming can achieve high productivity while substantially reducing the use of land and water compared to conventional outdoor agriculture. It also enables consistent, year-round, locally grown, and usually pesticide-free leafy-green vegetable production. Therefore, this type of farming operation can provide solutions to many global issues and integrate into industrial ecosystems in an urban context. However, indoor farming is technically demanding, requires large capital investment, has persistent costs for energy inputs, necessitates higher levels of worker skill and knowledge, and has significant unknowns in terms of economics, consumer trends, and long-term sustainability.This research and outreach project will help overcome major barriers to the profitable production of leafy greens in the rapidly developing indoor farming sector. We will 1) define and model the relationships among capex, opex, and revenues generated based on yields and high-valued attributes, and construct a relational map of optimal profitability points for indoor leafy-greens production; 2) Co-optimize indoor environmental conditions (humidity, air movement, temperature, light, and CO2 concentration) to increase yield and high-value attributes of leafy-green vegetables while minimizing opex; and 3) engage indoor farming stakeholders and collaborate with academic and industry groups working in controlled-environment agriculture. Our team of economists, agricultural engineers, lighting engineers, plant physiologists, horticultural scientists, and extension specialists will work closely with indoor growers and technology providers to develop and communicate affordable, improved technology and science-based new best practices. Stakeholders will be involved throughout the project, including performing on-farm trials to validate academic findings. An external advisory board composed of industry leaders and academics will provide valuable feedback. We will disseminate information generated from the project to stakeholders via multiple outreach outlets including websites, webinars, YouTube videos, conferences, publications, and an open-source data repository. Project outcomes and outputs will be consistent with the SCRI goal of addressing the critical needs of the specialty crop industry by developing and disseminating science-based tools to address critical stakeholder needs.

Animal Health Component

0%

Research Effort Categories

Basic

10%

Applied

60%

Developmental

30%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
203	1430	1020	10%
204	1430	1020	20%
204	1430	3010	10%
205	1430	1020	15%
205	1430	2020	15%
402	1430	2020	10%
502	1430	1010	10%
609	1430	3010	10%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 205 - Plant Management Systems; 609 - Economic Theory and Methods; 402 - Engineering Systems and Equipment; 502 - New and Improved Food Products;

Subject Of Investigation
1430 - Greens and leafy vegetables;

Field Of Science
2020 - Engineering; 1010 - Nutrition and metabolism; 3010 - Economics; 1020 - Physiology;

Keywords

controlled-environment agriculture

indoor farming

economics

indoor production technologies

Goals / Objectives
Our 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 opex 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, we 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 proposed 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 enhancement, environmental management recommendations, and insights for economic sustainability as well as market and consumer perception of locally produced crops.Objective 1. Define and model optimal profitability relationships among capex, opex, and revenues generated based on yields and high-value attributes for leafy greens produced indoors. The three subobjectives are: 1A) Collect primary economic data for the indoor farming industry and market-preferred attributes; 1B) Develop energy, water, and CO2 input/output models and conduct site-specific operational cost analyses; and 1C) Model, analyze, and evaluate combinations of identified and estimated parameters to maximize profitability.Objective 2. Co-optimize indoor environmental conditions (humidity, air movement, temperature, light, and CO2 concentration) to increase yield and high-value attributes of leafy-green vegetables while minimizing opex. The five subobjectives are: 2A) Develop phasic-optimization and close-canopy lighting strategies to optimize crop productivity while minimizing resource inputs; 2B) Develop lighting recipes that (i) use low-cost warm white LEDs and (ii) increase nutrient content and shelf life; 2C) Co-optimize total photon flux density with temperature, humidity, air current, and CO2 concentration to increase yield, reduce production time, and regulate quality attributes of leafy greens, while reducing tip burn and potentially minimizing capex and opex; 2D) Design and test more effective localized air-distribution methods suitable for indoor farming production systems; and 2E) Develop strategies to better manage humidity around plants in indoor farms.Objective 3. Engage stakeholders and collaborate with controlled-environment agriculture academic groups of wider scope. The five subobjectives are: 3A) Create science-based and practical production guidelines, tools, educational materials, and organize outreach events/workshops (including webinars) that will help stakeholders increase profitability of their indoor agriculture businesses; 3B) Continue expanding our communication network with stakeholders through the monthly Indoor Ag Science Café forum; 3C) Create knowledge resources to share; 3D) Conduct on-farm trials and provide consultation services to analyze individual cases and to apply research-based experimental findings; and 3E) Engage other academic groups including an SCRI-funded project on greenhouse lighting and the GLASE consortium.

Project Methods
We will develop a database that characterizes the indoor farming industry and its potential market. This database, which will be made public after data are anonymized, will include biomass production of leafy greens grown under different production environments and corresponding capex and opex inputs. It will also include attainable produce attributes, willingness-to-pay, as well as market-valued attributes of leafy greens produced indoors.We will develop steady-state energy, water, and CO2 input/output balance models of indoor farms to use for the leafy-greens production model. These models will have parameters such as electrical energy consumption from lighting and HVAC systems, evapotranspiration rate, plant photosynthetic rate, respiration rate, overall heat exchange characteristics, air exchanges, and outdoor climate conditions.We will integrate these databases with production-possibility scenarios to evaluate feasible optimal profit scenarios considering the relationships among output attributes, capex and opex, resulting produce attributes, and market demand. The optimal profitability model will be built using a Stage-Structured Matrix model and the three modules previously described. Periodic assessments of results and final simulation results will be validated in discussions with the Economics Committee members. Consolidated results will be published for the benefit of the entire industry.Red and green lettuces, kale, and arugula ("test crops") will be grown as baby greens on adjustable-height racks within a controlled-environment walk-in growth room under multi-channel, dimmable LED arrays at four array/crop-separation distances. Crop stands will be grown to harvest at each separation distance, with electrical input power adjusted to maintain the same light intensity at constant crop height for each test distance. We will measure biomass for each array/crop-separation treatment, expressing energy-conversion efficiency as total grams of shoot-biomass per square meter. We also will perform reciprocal experiments for each test species, in which the same power will be applied to LED arrays for each separation distance tested, so that light intensity (rather than energy consumption) will vary with separation distance.In subsequent phasic-optimization studies, different red:blue ratios will be tested during the lag phase of their growth curve. As each crop transitions from lag to exponential-phase growth, different light intensities will be delivered to optimize energy-use efficiency and shoot-biomass yield. During their exponential-growth phase leading to harvest, the proportion of blue will be reduced relative to red , and far red will be introduced at varying intensities in a series of experiments to promote leaf expansion.We will grow green- and red-leaf lettuce hydroponically to quantify how the light spectrum controls biomass gain and quality attributes utilizing, in part, white LEDs. Plants will be grown at two light intensities and six light spectrums and assessed for growth attributes. To improve leaf coloration, phytonutrient content, and shelf-life, we will expose plants to UV-A and/or blue light prior to harvest. At harvest, representative tissue samples will be lyophilized and analyzed for phytonutrients. A subset of leafy greens will be evaluated for their postharvest performance (shelf life).We will grow test crops under lighting recipes previously developed in this project at two light intensities and three temperatures to determine how temperature interacts with light quantity to regulate growth and quality attributes. Samples of three crops will be analyzed for phytonutrients and mineral nutrients. In a subsequent experiment, and based on results from above, we will grow the test crops at three light intensities and three CO2 concentrations to quantify how they interact to regulate growth parameters. Next, we will investigate how light intensity and temperature interact to regulate growth of leafy greens while considering energy inputs for lighting and air conditioning. Green- and red- leaf lettuce will be grown at two intensities and four temperature regimens. Growth and energy consumption during each growth cycle will be measured.We will grow leafy, romaine-type, and butterhead lettuce hydroponically under three daily light integrals with different day and night relative humidities and two CO2 concentrations, with or without vertical air circulation to quantify incidence of tip burn. Measurements will be made to quantitatively understand plant growth rate, transpiration rate, as well as leaf calcium concentration. Tip burn incidence will be recorded visually and tissue calcium concentration will be quantified. We will also examine additional lettuce cultivars to identify their sensitivity to tip burn under tip-burn inducing conditions.We will evaluate how lighting-crop separation distance influences horizontal air movement across shelving in indoor farms using computational fluid dynamics analysis. We will use forced-convection vertical and horizontal air-distribution systems, aiming to deliver a desired air-current speed. We will also evaluate various air-distribution patterns suitable for close-canopy lighting and other shelf designs. Collaborative efforts with commercial indoor farms will help determine the most effective and resource-efficient designs of localized air distribution and production system for indoor farms.We will evaluate direct and indirect measurement methodologies for transpiration rate. We will measure crop water consumption or use sensors to measure the psychrometric properties of moist air to indirectly quantify plant evapotranspiration. In addition, the effects of various environmental setpoints on transpiration rates will be evaluated experimentally at different light intensities, temperatures, and CO2 concentrations. A model will be developed and validated to develop a guideline for designing/selecting HVAC systems for indoor farms, and to improve HVAC system designs and operation.

Progress 09/01/22 to 08/31/23

Outputs
Target Audience:Our target audience consists of indoor (vertical) farming growers and operators, venture capital investors, research and development personnel for indoor farming equipment, greenhouse growers, indoor farming consultants, agricultural and mechanical engineers, university faculty and extension personnel, and undergraduate and graduate students. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Runkle (MSU) had two PhD students, one research technician (Annika Kohler), and one undergraduate student who performed indoor leafy greens research for this project. They were assisted by another research technician (Nathan Durussel). Nathan Kelly completed his Ph.D. in summer of 2024. Kelly and another Ph.D. student (Jiyong Shin) gained experience with experimental planning and design; data collection, analysis, and interpretation; synthesizing results; and communicating information to grower and scientific audiences. They also received training in responsible conduct of research and lab safety. Shin attended and presented at the American Society for Horticultural Science annual conference in Orlando, FL and the annual project stakeholder meeting at Purdue University. Lopez (MSU) had two M.S. students, two undergraduate students, and support from a research technician to perform indoor leafy greens research for this project. The M.S. students started in the spring of 2020 and fall 2021 and performed research and outreach related to accomplishing Objectives 2C and 3. The current student (Devin Brewer) is learning about and gaining experience with experimental planning and design; data collection, analysis, and interpretation; and synthesis of results and presentation. The students also received responsible conduct of research training. Mitchell (Purdue) had a Ph.D. student working on the project who interacted with all OptimIA partners, advisory board members, and stakeholders at the annual stakeholder meeting as well as with NCERA-101 members in Tucson, AZ. Both the Ph.D. student and a new M.S. student (who began fall semester, 2022) presented and interacted with NCERA-101 members at UC Davis. The M.S. student attended the American Society for Horticultural Science annual conference in Orlando, FL and presented his thesis work there. Kacira (Arizona) had two graduate students and one undergraduate student who were engaged in, and supported by, this project. One graduate student (Chris Kaufman) completed his M.S. program in Spring 2023. A new graduate student (Erick Dzetekey) started his research experiments on intermitted airflow with energy savings and to prevent tipburn. Kacira participated in activities and outreach efforts during Indoor AgScience Café webinar programs and had collaborative bi-weekly meetings with Kubota (OSU) and Valle de Souza (MSU) on development of economic and energy models. Former M.S. student KC Shasteen (Arizona) also participated in these meetings. Kubota (OSU) had one Ph.D. student (John Ertle) and four undergraduate students who were engaged in, and supported by, this project. Ertle served as moderator for some of the Indoor Ag Science Café webinars, attended the American Society for Horticultural Science annual conference in Orlando, FL, and earned his Ph.D. in 2023. Valle de Souza (MSU) had one Ph.D. student working on the project (Joseph Seong). In the past year, his studies focused on developing an optimization model for the indoor agriculture industry, resulting in the third and final chapter of his dissertation. He successfully graduated in August 2023, and alongside his methodological training, he honed networking and presentation skills while disseminating research findings to academia, industry stakeholders, and fellow graduate students. He attended two annual conferences with an international audience, and contributed to a department seminar for graduate students, in collaboration with another Ph.D. candidate on this project (Jiyong Shin) to introduce the indoor agriculture production system and present their research results. Furthermore, Joseph showcased his work at the department's Graduate Research Symposium. How have the results been disseminated to communities of interest?As detailed previously, we coordinated a monthly Indoor Ag Science Café forum (www.scri-optimia.org/cafe.php), participated in the COSI Big Science Celebration, held a workshop during Cultivate'23, posted on LinkedIn, and continued to develop our project website (www.scri-optimia.org) and learning modules for OptimIA University (https://optimiauniversity.org). The OptimIA University videos and most of the café webinars were recorded and are publicly available at no cost on their respective websites. In addition, we had a one-and-a-half day long advisory board and stakeholder meeting at Purdue University during which we shared information generated in this project, discussed application of results, and received input on future directions for this project and beyond. We wrote 12 trade magazine articles with national circulation, were interviewed for an additional 6 articles written about our project, and delivered presentations to industry groups and scientific audiences in several U.S. States and in Canada, China, Japan, and the United Arab Emirates. Finally, we shared research and outreach activities with members of two USDA working groups, Resource Optimization in Controlled Environment Agriculture (NE-1835) and Committee on Controlled Environment Technology and Use (NCERA-101). What do you plan to do during the next reporting period to accomplish the goals?Kubota (OSU) will publish the rest of the research conducted with support from this project. She will also continue collaborating with members of Modeling Working Group for evaluating various scenarios for tipburn risks. She will continue organizing Indoor Ag Science Café webinars and begin integrating with other controlled-environment agriculture sectors and professionals (greenhouses, other non-leafy crops grown indoors) to become a critical educational resource serving the greenhouse/indoor growing community at large. Valle de Souza (MSU) will conclude the labor requirements analysis, offering additional insights into labor efficiency indices. Additionally, her team will enhance the optimization model by considering factors such as the selection of farm size and proximity to urban areas, while simultaneously improving energy efficiency. Further model simulations will be conducted to derive conclusions regarding the interrelationships among capital expenditure, operational expenditure, and revenue generation, with a focus on yield and high-value attributes for indoor-grown leafy greens. The outcomes of both the labor requirements analysis and the sustainable profitability optimization will significantly contribute to a more comprehensive understanding of the socio-economic impact of indoor agriculture. This research is anticipated to result in the publication of two peer-reviewed papers. Kacira (Arizona) will continue experiments to evaluate the effects of vertical and horizontal air flow to mitigate tipburn with lettuce crops with intermitted airflow strategies. Computational fluid dynamics modeling will evaluate air flow uniformity inside a vertical farm system with alternative air distribution system designs. He will continue collaborations with the economic model development team, to develop methods with experimental measurements, and to determine crop transpiration and water use to improve humidity management in indoor vertical farming systems. Mitchell (Purdue) will develop an additional narrated video about baby greens for OptimIA University during the forthcoming reporting period. He will work with his former Ph.D. student to publish manuscripts in scientific journals. An undergraduate research project investigating the possibility of mat-based culture for baby-green culture will be completed and a manuscript will be developed for publication. The M.S. student project investigating effects of increasing light intensities for indoor lettuce production on energy-use efficiency and product quality will be completed and manuscripts developed for publication. Runkle (MSU) will perform research investigating the effect of total light intensity on blue light and far-red light on lettuce growth and quality. To address this subject, multiple experiments indoors in highly controlled environments are planned, each replicated in time. He will develop a learning module for OptimIA University and work towards publishing results of three experiments in peer-reviewed journals. Runkle and Lopez (MSU) will host a one-day lighting workshop that will include research results from this project. Finally, we will present our information to growers and allied trades at industry meetings as well as academics at scientific conferences. Lopez (MSU) has completed all end-of-production light and temperature studies. Anthocyanin, carotenoid and nutrient analysis is ongoing. He will develop narrated videos about culinary herbs, microgreens, and temperature management for OptimIA University. Additionally, he will disseminate the results of his collective studies to stakeholders via peer-reviewed journals, trade articles, OptimIA research reports, and webinars. All team members will collaborate on outreach activities and outputs including writing trade magazine articles, developing the last learning modules for OptimIA University, adding resources to our project website, and holding our last stakeholder and advisory committee meeting. We will also deliver presentations to grower and industry audiences.

Impacts
What was accomplished under these goals? Our project goal is to increase the sustainability and hence profitability of the commercial production of leafy greens in vertical farms. To accomplish this, we are determining environmental conditions that can increase yield and product quality while also minimizing inputs, especially for energy. We are also understanding operational and capital expenditures to produce leafy greens indoors, as well as define risk and production scenarios that are most profitable. Objective 1. Before our project commenced, there was very little economic information on the indoor production of leafy green vegetables. We have performed interviews and surveys of indoor farmers and consumers of leafy greens, as well as scoured the literature and other resources to better understand the economics of vertical farming. Valle de Souza (Michigan State University, MSU) and her team have completed the analysis of consumer survey data, uncovering several aspects of the indoor agriculture markets. They have defined key quality attributes of indoor farm-produced leafy greens and conducted a detailed analysis of consumer attitudes toward this innovative production system. The economics team led by Valle de Souza (MSU) has extended the foundational model developed in collaboration with team members Kubota (The Ohio State University, OSU) and Kacira (University of Arizona) to encompass additional components for a comprehensive analysis of operating costs related to leafy greens. Objective 2. Until recently, there was very little information on how environmental parameters such as light, temperature, and humidity can be co-optimized to maximize yield and product quality. We have performed numerous experiments to quantify how these parameters independently and interactively regulate the growth of leafy greens grown indoors, without sunlight. Following earlier efforts of assessing cultivar-specific tipburn sensitivity, Kubota (OSU) evaluated 20 more cultivars to tipburn sensitivity. Tipburn symptoms were apparent as early as 16 days after transplanting and the symptom severity of 20 cultivars ranged between 0 and 58 % of all leaves. There was no correlation between yield and tipburn sensitivity. Kubota (OSU) examined the effect of lowering the daily light integral only during the end of production, which is when tipburn typically appears. At harvest, tipburn severity was reduced by lowering the light level, but the magnitude of reduction was cultivar-specific. However, decreasing light also decreased yield. Kubota (OSU) examined nighttime dim lighting and vertical downward airflow to mitigate tipburn in lettuce. Two tipburn-sensitive lettuce cultivars were grown under tipburn-inducing conditions. Lighting during the night with blue or blue+red light did not mitigate tipburn severity. In contrast, vertical downward airflow (all day) eliminated tipburn, regardless of dim lighting. Kubota (OSU), Kacira (Arizona) and Valle de Souza (MSU) analyzed high-density short-cycle production of lettuce as a means to avoid tipburn in lettuce. Short-cycle, high plant-density production allows similar productivity as plants grown with a longer cycle and lower density but without tipburn. Furthermore, the economic analysis indicates that farm size and location are important determinants of profitability in this short-cycle production scenario. Kacira (Arizona) competed experiments with lettuce that evaluated use of vertical and horizontal airflow to mitigate tipburn. He also designed and installed a new air distribution system, as an outcome of computational fluid dynamics modeling, at the UArizona Vertical Farm facility to deliver vertical and horizontal air flow to the plant canopy to mitigate tipburn in lettuce. Mitchell (Purdue University) performed validation studies that confirmed that carbon dioxide (CO2) concentration and far-red light interacted differently at several early crop-growth stages of red-leaf lettuce. Results indicate that indoor growers can tailor the environment to the crop, especially the lighting environment, rather than just grow different salad crops in a constant compromised environment from start to harvest. Mitchell (Purdue) developed Minitron III crop photosynthetic dose-response curves for 'Rouxai' lettuce utilizing different light intensities and CO2 concentrations at different growth stages. Photosynthetic capacity progressively increased with stages of crop maturity. Data generated from this experiment informs growers how light intensity and CO2 can be controlled to maximize growth during different stages of the lettuce production cycle. Mitchell (Purdue) grew green 'Rex' and red 'Rouxai' lettuce under various light intensities and measured plant growth and energy consumption. Results indicate that growing either cultivar above 300 micromoles of light is not energy efficient for increasing plant size or biomass. Lopez (MSU) conducted a series of experiments to quantify the effects of light intensity, day and night temperature, and CO2 concentration on lettuce biomass, color, and quality. Results show that end-of-production cooling significantly increased foliage coloration and nutrient and anthocyanin content of leafy greens. Using a low temperature instead of a lighting treatment at the end of production offers an alternative method to increase crop quality at harvest. Runkle (MSU) completed research with frill-leaf lettuce to determine effects of light intensity and quality on growth and shelf life. Generally, shoot fresh mass, leaf size, and leaf color decreased as the proportion of blue light increased or the daily light integral decreased. For at least one cultivar, shelf life was shortest when grown under the highest fraction of blue light and the highest light intensity. Runkle (MSU) authored a scientific review article that included a meta-analysis of scientific publications on effects of far-red light on leaf length and biomass accumulation. Objective 3. A critical component of this project is to engage with stakeholders (especially our advisory committee, indoor farming owners, managers, and growers) when designing experiments and gathering economic information, as well as to communicate research-based information generated in this project. The major outreach programs of our project were our annual stakeholder meeting at Purdue University, the Indoor Ag Science Café monthly webinar, development of OptimIA University learning modules, a 3.5-hour workshop on hydroponics that focused on growing leafy greens indoors held at Cultivate'23, and continued updates to our project website. The Indoor Ag Science Café series (https://scri-optimia.org/cafe.php) provides current information about indoor farming technologies and educational opportunities to learn the basics necessary for designing and operating indoor farms. There have been 54 webinars since August 2018, and currently there are 1,359 members (as of August 2023). Our project website (https://scri-optimia.org), which includes articles, publications, highlights, tools, and recorded videos for the indoor farming and related industries, had 2,460 visits during the reporting period. The OptimIA University website (https://optimiauniversity.org) had 3,969 visits during the reporting period. In total, these two websites received 1,506 unique visits, 869 first-time visits, and 637 returning visits. Our leafy greens project uses LinkedIn to promote the Indoor Ag Science Café recordings, conference presentations, and survey announcements. During the reporting period, our LinkedIn profile increased by 59% to 471 followers. The LinkedIn page received 139 total reactions, 242 unique visitors, 492 visitor page views, and 33 custom button clicks. It is available at https://www.linkedin.com/feed/update/urn:li:activity:7019302046579265537.

Publications

• Type: Other Status: Published Year Published: 2023 Citation: Seong, J., S. Valle de Souza and H.C. Peterson. 2023. Can indoor agriculture feed growing urban population while achieving economic sustainability and energy use? Agricultural and Applied Economic Association Annual Meeting, Washington, D.C
• Type: Other Status: Published Year Published: 2022 Citation: Seong, J., S. Valle de Souza and H.C. Peterson. 2022. Consumer varieties in the market for indoor agriculture-produced leafy greens. AFRE Department Brown Bag Seminars, Michigan State University. East Lansing, MI.
• Type: Other Status: Published Year Published: 2023 Citation: Sheibani, F. and C. Mitchell. 2023. Close-canopy lighting: an approach to improve crop canopy photon capture. NCERA-101 conference, Davis, CA.
• Type: Other Status: Published Year Published: 2023 Citation: Shin, J. and E.S. Runkle. 2023. Interactions between photon spectra and air temperature on lettuce and basil foliage coloration. ASHS Annual Conference, Orlando, FL.
• Type: Other Status: Published Year Published: 2023 Citation: Valle de Souza, S. 2023. Economics of vertical farms (Cost and profitability). Greenhouse Training Online, Univ. of Florida.
• Type: Other Status: Published Year Published: 2023 Citation: Valle de Souza, S., J. Seong, A. Cohen, S. Oh, and C.H. Peterson. 2023. Current state of indoor agriculture production systems: A snapshot of labor requirements and automation choices. ASHS 2023 Annual Conference, July 30 to August 4th, 2023, Orlando, FL, USA
• Type: Other Status: Published Year Published: 2022 Citation: Valle de Souza, S., J. Seong, A. Cohen, S. Oh, and C.H. Peterson. 2022. Labor requirements in indoor agriculture. Laboratoire sur l'Agriculture Urbaine & CRETAU Seminar Series, Montr�al, Quebec, Canada.
• Type: Theses/Dissertations Status: Published Year Published: 2022 Citation: Bates, J.P. 2022. Crop-specific sensitivity to nutrient availability in low-pH hydroponic nutrient solution. M.S. thesis, Department of Horticulture and Crop Science, The Ohio State University, Columbus [Major advisor: C. Kubota].
• Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Ertle, J.M. 2023. Tipburn management through controlled environment for indoor vertical farm lettuce production. Ph.D. dissertation, Department of Horticulture and Crop Science, The Ohio State University, Columbus [Major advisor: C. Kubota].
• Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Kaufmann, C. 2023. Reducing tipburn in lettuce grown in indoor vertical farm: Comparing the impact of vertically distributed airflow vs. horizontally distributed airflow in the growth of Lactuca sativa. M.S. thesis, Department of Biosystems Engineering University of Arizona, Tucson [Major advisor: M. Kacira].
• Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Kelly, N. 2023. The effects of the photon spectrum on growth and quality attributes of leafy greens produced indoors. Ph.D. dissertation, Department of Horticulture, Michigan State University, East Lansing [Major advisor: E. Runkle].
• Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Seong, J. 2023. Consumer acceptance and optimization strategies for sustainable indoor agriculture: Exploring attitudes, preferences, and economic-environmental trade-offs. Ph.D. dissertation, Department of Agriculture, Food, and Resource Economics and Department of Economics (dual major), Michigan State University, East Lansing [Major advisor: S. Valle de Souza].
• Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Sheibani, F. 2023. Enhancing resource-use efficiency for indoor farming. Ph.D. dissertation, Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette [Major advisor: C. Mitchell].
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Abedi, M., X. Tan, E.J. Stallknecht, E.S. Runkle, J.F. Klausner, M.S. Murillo, and A. B�nard. 2023. Incorporating the effect of the photon spectrum on biomass accumulation of lettuce using a dynamic growth model. Front. Plant Sci. 14:1106576.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Ertle, J.M. and C. Kubota. 2023. Reduced daily light integral at the end of production can delay tipburn incidence with a yield penalty in indoor lettuce production. HortScience 58:1217-1224.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Ertle, J.M. and C. Kubota. 2023. Testing cultivar-specific tipburn sensitivity of lettuce for indoor vertical farms. HortScience 58:1257-1266.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Kelly, N. and E.S. Runkle. 2023. End-of-production ultraviolet A and blue light similarly increase lettuce coloration and phytochemical concentrations. HortScience 58:525531.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Kubota, C., G. Papio, and J. Ertle. 2023. Technological overview of tipburn management for lettuce (Lactuca sativa) in vertical farming conditions. Acta Hortic. 1369:65-73.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Meng, Q. and E.S. Runkle. 2023. Blue photons from broad-spectrum LEDs control growth, morphology, and coloration of indoor hydroponic red-leaf lettuce. Plants 12(5):1127.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Seong, J., S. Valle de Souza, and H.C. Peterson. 2023. Seeds of industry sustainability: Consumer attitudes towards indoor agriculture benefits versus its advanced technology. Sustainability 15:2369.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Shasteen K, and M. Kacira. 2023. Predictive modeling and computer vision-based decision support to optimize resource use in vertical farms. Sustainability 15(10): 7812.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Shasteen, K.C., J. Seong, S. Valle De Souza, C. Kubota, and M. Kacira. 2023. Optimal planting density: Effects on harvest time and yield. Acta Hortic. 1369:41-48.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Sheibani, F., M. Bourget, R. Morrow, and C. Mitchell. 2023. Close-canopy lighting, an effective energy-saving strategy for overhead sole-source LED lighting in indoor farming. Front. Plant Sci. 14:1215919.
• Type: Journal Articles Status: Published Year Published: 2023 Citation: Tarr, S. S. Valle de Souza, and R.G. Lopez. 2023. Influence of day and night temperature and radiation intensity on growth, quality, and economics of indoor green butterhead and red oakleaf lettuce production. Sustainability 15:829.
• Type: Other Status: Published Year Published: 2023 Citation: Kubota, C. and J. Ertle. 2023. Lettuce tipburn sensitivity trial  Preliminary results. eGRO Edible Alerts Vol 8.10.
• Type: Other Status: Published Year Published: 2022 Citation: Kubota, C., E. Runkle, C. Mitchell, and R. Lopez. 2022. Answering key questions about indoor crops. Inside Grower Nov.:14-15.
• Type: Other Status: Published Year Published: 2023 Citation: Kubota, C., S. Offenbecher, and R. Conrad. 2023. Pericarp cracking and moisture management to improve spinach germination. eGRO Edible Alerts Vol 8.12.
• Type: Other Status: Published Year Published: 2023 Citation: Peterson, H.C., S. Valle de Souza, and J. Seong. 2023. Questions about consumer behavior. Inside Grower May: 14-15.
• Type: Other Status: Published Year Published: 2023 Citation: Peterson, H.C., S. Valle de Souza, and J. Seong. 2023. The cost of indoor farming. Inside Grower Feb.:14-17.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E. 2023. Lighting plants indoors, without sunlight. Greenhouse Product News 33(5):10.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E. 2023. Advancements in horticultural lighting. Greenhouse Product News 33(3):10.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E., J. Shin, and N. Kelly. 2023. A closer look at the effect of white LEDs on plant performance. Greenhouse Grower 41(1):26-28.
• Type: Other Status: Published Year Published: 2022 Citation: Runkle, E. 2022. Far-red light in greenhouse and indoor farming. Greenhouse Product News 32(10):50.
• Type: Other Status: Published Year Published: 2023 Citation: Tarr, S. and R.G. Lopez. 2023. Optimize your production parameters. Produce Grower Aug.:13-16.
• Type: Other Status: Published Year Published: 2023 Citation: Tarr, S. and R.G. Lopez. 2023. Unlocking the potential of indoor lettuce production. Produce Grower Oct.:1213.
• Type: Other Status: Published Year Published: 2023 Citation: Valle de Souza, S., H.C. Peterson, and J. Seong. 2023. Economies of scale. Inside Grower Aug.: 22-24.
• Type: Other Status: Published Year Published: 2023 Citation: Brewer, D. and R.G. Lopez. 2023. Improving red leaf lettuce foliage color with blue + red end-of-production sole-source lighting and end-of-production cooling. ASHS Annual Conference, Orlando, FL.
• Type: Other Status: Published Year Published: 2023 Citation: Gildersleeve, M., F. Sheibani, and C. Mitchell. 2003. Impacts of increasing light intensity for indoor production of Rouxai and Rex lettuce crops in the context of energy-use efficiency. NCERA-101 conference, Davis, CA.
• Type: Other Status: Published Year Published: 2023 Citation: Gildersleeve, M., F. Sheibani, and C. Mitchell. 2023. Impacts of increasing light intensity for indoor production of Rouxai and Rex lettuce crops in the context of energy-use efficiency, ASHS Annual conference, Orlando, FL.
• Type: Other Status: Published Year Published: 2023 Citation: Kacira, M. 2023. Monitoring greenhouse environments. 22nd Annual UA-CEAC Annual Greenhouse Crop Production and Engineering Design Short Course, The University of Arizona, Tucson, AZ.
• Type: Other Status: Published Year Published: 2023 Citation: Kacira, M. 2023. Resource use efficient and precision-controlled environment agriculture. Cornell University Ezra Round Table Seminar Series (online).
• Type: Other Status: Published Year Published: 2023 Citation: Kacira, M. 2023. Advancement of plant sensing technology for sustainable crop production under controlled environment. OH-CEAC Conference: Advancement of Sustainable Controlled Environment Crop Production Sciences & Technologies, Columbus, OH.
• Type: Other Status: Published Year Published: 2023 Citation: Kubota, C. 2023. Growing healthy leafy greens with low-pH hydroponic solutions. International Symposium on Plant Factory, Chiba, Japan.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E. 2023. Considerations of utilizing far-red light for indoor production of leafy greens. ISHS VertiFarm Second International Workshop on Vertical Farming, Chengdu, China.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E. 2023. The photon spectrum and its manipulation in horticulture. Departmental Seminar Series, Department of Horticulture, Michigan State Univ., East Lansing, MI.
• Type: Other Status: Published Year Published: 2023 Citation: Runkle, E. 2023. The light spectrum regulates crop quality and yield. USDA-ARS, DOE, and NASA Workshop on Advancing Controlled Environment Agriculture on Land and in Space in the Next 20 Years, Toledo, OH.
• Type: Other Status: Other Year Published: 2023 Citation: Runkle, E. 2023. Towards optimizing indoor lighting of leafy greens. Second Annual AeroFarms AgTech Innovation Summit, Abu Dhabi, United Arab Emirates.

Progress 09/01/21 to 08/31/22

Outputs
Target Audience:Our target audience consists of indoor (vertical) farming growers and operators, venture capital investors, research and development personnel for indoor farming equipment, greenhouse growers, indoor farming consultants, agricultural and mechanical engineers, university faculty and extension personnel, and undergraduate and graduate students. Changes/Problems:Controlled-environment work is inherently slow because of periodic failures of sensors, cooling systems, and equipment that run continuously during cropping experiments. For example, some of the lighting fixtures inside the Controlled Environment Lighting Lab at MSU have failed, which has limited research progress. Maintenance, repair, and replacement of environmental-control components are inevitable and part of the ongoing controlled-environment research process. In addition, purchased product delivery delays occurred due to shipment and logistics delays. One continuing limitation is for collection of economic data; industry members remain reluctant to share their economic data for modelling and research purposes. This is forcing the team to expand data collection beyond the US domestic industry. What opportunities for training and professional development has the project provided?At OSU, one PhD student (Ertle) and two undergraduate students were engaged in, and supported by, this project. One undergraduate student (Krage) trained last year through assisting graduate students in this program conducted their own project, analyzed the data, and presented at the annual conference. In the Department of Horticulture at MSU, two PhD students, two MS students, two undergraduate students, and a research technician (Kohler) performed indoor leafy greens research for this project. They were assisted by another research technician (DuRussel), who assisted with experimentation. Ph.D. student Kelly started in fall of 2019 and Ph.D. student Shin in fall of 2021. The MS students (Tarr and Brewer) started in the spring of 2020 and fall 2021. All students and technicians are performing research and outreach related to accomplishing Objectives 2C and 3. All students are learning about and gaining experience with experimental planning and design; data collection, analysis, and interpretation; synthesis of results and presentation. They also received responsible conduct of research training. The students have also gained experience presenting science-based information generated in this project to industry and scientific audiences. At Purdue, one PhD graduate student (Sheibani) interacted by direct participation at the 2022 ASHS conference networking with conferees, asking and answering questions, and making comments about her presented research in both poster and oral sessions. She also participated in many ASHS scientific sessions, gaining knowledge and perspective about current advances in indoor agriculture. She also gained valuable experience mentoring undergraduate engineering technology and life sciences students assisting in her research projects or conducting their own guided capstone or for-credit research projects. Kubota (OSU), Kacira (Arizona) and Valle de Souza (MSU) are working together to develop a course for OptimIA University, a page on the project website to be made available to the public in December 2022. This will encompass a series of lectures with practical exercises to support growers in production planning and management. Two graduate students have been trained through the period as part of these efforts. At Arizona, two graduate students and one undergraduate student were engaged in, and supported by, this project. One graduate student (Shasteen) completed his MS program in Aug. 2022. Graduate student (Shasteen) presented his work from this project at the Vertical Farming Symposium of 2022 International Horticulture Congress, held in Angers, France. How have the results been disseminated to communities of interest?We coordinated a monthly Indoor Ag Science Café forum (www.scri-optimia.org/cafe.php), participated in the COSI Big Science Celebration at OSU, posted on social media channels, and continued to develop our project website (www.scri-optimia.org). Most of the Café webinars were recorded and are publicly available on the project website. The economics team (led by Valle de Souza at MSU) has presented preliminary results from survey analysis to industry partners, academia, and to the general public. Feedback from partners contributed to shape further research developments. For example, the project is now encompassing further studies on indoor agriculture labor to provide advice on current workforce issues faced by the industry. In addition to writing articles for industry magazines and scientific journals, we have shared research results and project activities with different industry and academic audiences including the following meetings and conferences: All team members presented research and outreach updates at the 3rd annual stakeholder meeting held in a in-person format in Tucson, AZ. The American Society for Horticultural Science Annual Conference held in Chicago, IL. International Horticultural Congress, International Symposium on Advances in Vertical Farming held in a hybrid format in Angers, France. NE-1835 (Resource Optimization in Controlled Environment Agriculture) working group held in a hybrid format in Chicago, IL. NCERA-101 (Committee on Controlled Environment Technology and Use) working group held in Tuscon, AZ (and technical tours). UArizona-CEAC Greenhouse Engineering and Crop Production Short Course. Indoor AgScience Café presentations. What do you plan to do during the next reporting period to accomplish the goals?Kacira's team (Arizona) will continue experiments to evaluate the effects of vertical and horizontal air flow to mitigate tipburn with lettuce crops. They will perform CFD modeling to evaluate air flow uniformity in indoor vertical farm systems, continue collaborations with the economic model development team, and continue working on developing methods with experimental measurements and modeling for determining crop transpiration and water use to help with improved humidity management in indoor vertical farming systems. They will also continue sharing project outcomes with various stakeholders with publications, presentations, and workshops. Kubota's team (OSU) will continue working on developing an effective mitigation method of lettuce tipburn. Specifically, nighttime dim lighting approach will be combined with airflow to increase the efficacy. Simple models to assess potential growth rate of lettuce crops developed in the previous year will be refined to use in the tipburn assessment. They will also continue working with indoor farms to help them assess their microclimate conditions using the developed tools. Lopez's and Runkle's team (MSU) will combine all the environmental and cultural data generated from previous OptimIA studies to optimize lettuce growth and development under white LEDs. Given that anthocyanin production in red-leaf lettuce is not maximized under white light, Lopez's team will expose plants to end-of-production lighting containing blue light alone or in combination with red light and at a range of temperatures. Anthocyanins, phytonutrients, tip-burn incidence, consumer preference, and post-harvest shelf-life will be quantified to determine the treatments that lead to the highest quality lettuce. Runkle's team (MSU) will perform an experiment focused on the interactions of light intensity and quality on canopy growth and biomass accumulation. They will also repeat a lighting study that investigates the effect of lighting conditions on the postharvest performance of frill-leaf lettuce. They will also work towards publishing results of three experiments that were recently completed. Finally, they will make some changes to the lighting system inside the Controlled Environment Lighting Laboratory and install a system that enriches the air with carbon dioxide. Mitchell's team (Purdue) will create an additional narrated video about baby greens for OptimIA University and write a manuscript about the completed close-canopy-lighting work. CO2 and light dose-response curves for 'Rouxai' lettuce will be repeated, extended to higher intensities of light than previously, and validated. A manuscript about Minitron III will be developed including those dose-response data as proof of concept for facility capabilities. The focused-lighting work will continue using Minitron III, comparing lettuce-growth parameters and energy use for focused versus full-coverage lighting over entire cropping cycles starting with well-spaced seedlings through canopy closure. Energy-use efficiency will be measured as well as crop-growth parameters. The CO2 x far-red light study will be repeated, and once statistically validated, will be submitted for publication to a refereed journal. A new M.S. graduate student at Purdue will investigate effects and implications (energy-use, product quality) of growing lettuce crops at higher light intensities than currently is of common practice. This work is inspired by questions, goals, and plans expressed by indoor growers across the country. His work will include measurements of multiple plant-growth parameters for multiple lettuce cultivars, energy measurements for lighting, gas exchange by crops at a wide range of light intensities and crop-development stages, mineral and phytonutrient analysis of baby and leafy greens, as well as organoleptic quality evaluations resulting from environmental treatments, especially light intensity and spectrum. Valle de Souza's team (MSU) will collect further primary and secondary data through a labor survey and will continue assessing industry needs through trips, interviews, and research. Farm operations including capex and opex information are being incorporated to the profit optimization model. Results from Objective 2 will also be incorporated to the model.

Impacts
What was accomplished under these goals? The indoor farming industry in the U.S. continues to rapidly expand yet faces challenges of maximizing crop yield while minimizing input costs. To date, our project has identified recommended growing conditions (lighting, temperature management, humidity, etc.) to increase growth of leafy greens while also considering plant quality and operational costs, including energy. We are identifying production approaches that maximize yield considering time, planting density, light intensity, and other factors based on plant science, agricultural engineering, and economics. Objective 1A: Valle de Souza (MSU) analyzed primary survey data and produced estimates of consumers' willingness to pay for attributes to be used in the market demand section of the optimization model and informed about preferred attributes to be targeted by the profit optimization model. Objective 1B: The modeling working group (Kubota, Valle de Souza, Kacira) have completed the base model for energy, and input/output models, which serves as a framework for the final optimization model. Analysis using this model has been presented in conferences and academic seminars as well as to the industry. Objective 1B: Kacira Lab (Arizona) developed a model determining the effects of planting density on yield outcomes. This model was integrated into the overall economics model to evaluate various what-if scenarios with effects of planting density and economic outcomes from a production strategy. Objective 1B: Kacira (Arizona) completed a machine vision application and implemented a predictive modeling-based system that monitors crop growth and yield and performs planting density optimization and yield predictions. The data supported development of a planting density modeling study and its integration into an economics model to study various production strategies. Objective 1C: Valle de Souza (MSU) continued to develop a mathematical model describing optimal profitability relationships among capex, opex, and revenue generated by indoor producers of leafy greens. Specifically, the economics team is implementing further complexity to the base model that now takes the format to encompass capex and opex variables. Objective 2A: Mitchell (Purdue) investigated the effects of three different concentrations of CO2 and four different levels of far-red light and found that they interacted differently for several growth and development parameters at three different stages of early lettuce production. Objective 2A: Mitchell (Purdue) studied how close-canopy lighting impacted lettuce growth and energy consumption. Lettuce crops grew to the same extent but consumed significantly lower energy for lighting when LED lamps were dimmed to the same light intensity at closer lamp/crop-separation distances, or crops yielded significantly more at closer separation distances if lights were not dimmed from the intensity used at the farthest separation distance, keeping the same energy-consumption rates at all separation distances. Objective 2A: Mitchell (Purdue) developed software for the Minitron III crop-cuvette / controlled-environment growth facility to automate post-experiment conversions of raw gas-exchange data into crop photosynthetic rates. The program also calculates dark respiration rates. Objective 2B: Runkle (MSU) revealed that high air temperature enhances the positive effect of low red to far-red light ratio on increasing lettuce and basil growth, but in lettuce, it was at the expense of some quality attributes. Objective 2B: Research by Runkle (MSU) indicated that blue light plays an important role in attenuating the negative effects of high air temperature and low red to far-red light ratio on plant growth of basil and lettuce. Objective 2B: Preliminary results of an experiment by Runkle (MSU) indicate that a high percentage of blue light (relative to red light) and a high light intensity kept frill-leaf lettuce plants compact and greener compared to lower percentages of blue light. Objective 2B: Runkle (MSU) showed that only red light during the entire production cycle produced red-leaf lettuce with the greatest fresh mass but leaves lacked red color. Growing plants under red light followed by blue or a mixed light spectrumproduced higher-quality lettuce with a similar biomass as plants grown under continuous red light. Objective 2B: In a far-red light study, preliminary results of Runkle (MSU) suggest that lettuce biomass was the lowest when either no far-red light was present or when far-red light was delivered at its highest intensity, as long as green light was included in the lighting spectrum. Objective 2C: Kacira (Arizona) completed experiments with lettuce grown under three daily light integrals and with dynamic control of CO2 concentration. The data obtained from these experiments serve as input variables for crop growth model validation studies (Objectives 1B, 1C and 2C). Objective 2C: Kacira (Arizona) designed and installed a new air distribution system, as an outcome of CFD modeling, at the UArizona Vertical Farm facility to deliver vertical and horizontal air flow to plant canopies to mitigate tipburn in lettuce. Objective 2C: Kubota (OSU) created tip-burn inducing conditions that would limit transport of calcium while achieving a fast growth rate of lettuce. Cultivars originally developed for outdoor production exhibited tipburn at a significantly higher rate than those developed for indoor or greenhouse production. Objective 2C: Kubota (OSU) examined a new approach to mitigate tipburn. During the 8-h "nighttime", light with two different spectra were applied at a low intensity. In both cultivars, nighttime dim lighting significantly enhanced stomatal conductance but did not alleviate tipburn. Objective 2C: Kubota (OSU), Kacira (Arizona) and Valle de Souza (MSU) collaborated in evaluating high-density short-cycle production of lettuce to avoid tipburn. Our results confirmed this production approach allows similar productivity as plants grown with a longer cycle and lower density but without tipburn. Objective 2C: Lopez (MSU) conducted a series of experiments to quantify the effects of light intensity, day and night temperature, and carbon dioxide concentration on lettuce biomass, color, and quality. Objective 3A: Kubota's lab (OSU) participated in the Center of Science Innovation "Big Science Celebration" that had 25,000 community members in attendance. Attendees were able to ask questions, look and touch two hydroponic systems, and leafy greens at different growth stages. Objective 3B: The Indoor Ag Science Café series continued to make significant impacts to stakeholders by providing current information about indoor farming technologies and educational opportunities. We have delivered 43 cafes since August 2018, and during that time, membership has increased to 1,330 members. The six most-viewed videos produced during the reporting period had a cumulative total of 10,871 views. Objective 3C: Our project website, which includes articles, publications, highlights, tools and recorded videos for indoor farming and related industries, had 10,147 visits and 27,421 page views during the reporting period. The project also uses LinkedIn and Facebook to promote project activities. Objective 3D: In a study by Runkle (MSU) and a stakeholder partner, research with different kinds of white LEDs indicated that lettuce and kale had a similar yield, leaf morphology, and leaf coloration when the intensity of blue light and total photosynthetic light were constant. Objective 3D: Runkle (MSU), in collaboration with a stakeholder partner, collected growth and coloration data of lettuce and basil grown under different light spectrum compositions. Partially substituting other wavebands with far-red light increased fresh weight but leaves had less coloration.

Publications

• Type: Journal Articles Status: Published Year Published: 2021 Citation: Gillespie, D.P., G. Papio, and C. Kubota. 2021. High nutrient concentrations of hydroponic solution can improve growth and nutrient uptake of spinach (Spinacia oleracea L.) grown in acidic nutrient solution. HortScience 56:687-694.
• Type: Book Chapters Status: Published Year Published: 2022 Citation: Park, Y., C. Gomez, and E.S. Runkle. 2022. Indoor production of ornamental seedlings, vegetable transplants, and microgreens, p. 351-375. In: Kozai et al. (eds.). Plant Factory Basics, Applications, and Advances. Academic Press, London.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: van Delden., S.H., M. SharathKumar, M. Butturini, L. J. A. Graamans, E. Heuvelink, M. Kacira, et al. 2022. Current status and future challenges in implementing and upscaling vertical farming systems. Nature Food 2:944956.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Vaatakait?-Kairien?, V., A. Brazaityt?, J. Miliauskien?, and E.S. Runkle. 2022. Red to blue light ratio and iron nutrition influence growth, metabolic response, and mineral nutrients of spinach grown indoors. Sustainability 14:12564.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Walters, K.J. and R.G. Lopez. 2022. Basil seedling production environment influences subsequent yield and flavor compound concentration during greenhouse production. PLoS ONE 17(8):e0273562.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Walters, K.J. and R.G. Lopez. 2022. Hydroponic basil production: Temperature influences volatile organic compound profile, but not overall consumer preference. Horticulturae 8(1):76.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Zhang, Y. and M. Kacira. 2022. Analysis of climate uniformity in indoor plant factory system with computational fluid dynamics (CFD). Biosystems Engineering, 220:73-86.
• Type: Other Status: Published Year Published: 2022 Citation: Kelly, N., Q. Meng, and E. Runkle. 2022. Photoperiod, light intensity, and daily light integral. Produce Grower Mar.:16-19.
• Type: Other Status: Published Year Published: 2022 Citation: Lopez, R.G., C. Kubota, E. Runkle, and C. Mitchell. 2022. Indoor farming FAQ: Introduction, challenges, and opportunities. Inside Grower May:1415.
• Type: Other Status: Published Year Published: 2021 Citation: Meng, Q. and E. Runkle. 2021. Far-red and PPFD: A tale of two lettuce cultivars. Produce Grower Oct.:20-24.
• Type: Other Status: Published Year Published: 2022 Citation: Meng, Q. and E. Runkle. 2022. Fixed vs. dynamic light quality for indoor hydroponic lettuce. Produce Grower Feb.:14-17.
• Type: Book Chapters Status: Published Year Published: 2022 Citation: Kelly, N., V. Vaatakait?-Kairien?, and E.S. Runkle. 2022. Indoor lighting effects on plant nutritional compounds, p. 329-349. In: Kozai et al. (eds.). Plant Factory Basics, Applications, and Advances. Academic Press, London.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Mitchell, C. 2022. History of controlled environment horticulture: indoor farming and its key technologies. HortScience 57:247256.
• Type: Other Status: Published Year Published: 2021 Citation: Runkle, E. 2021. The buzz of secondary metabolites. Greenhouse Product News 31(11):42.
• Type: Other Status: Published Year Published: 2022 Citation: Runkle, E., M. Kacira, and C. Mitchell. 2022. More questions answered. Inside Grower Aug.:16-17.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Brewer, D. and R.G. Lopez. 2022. Increasing day and night temperature and carbon dioxide concentration influence growth and development of red and green lettuce (Lactuca sativa). 2022 XXXI International Horticultural Congress: IHC2022, Angers, France.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Ertle, J.M. and C. Kubota. 2022. Tipburn inductive conditions for testing cultivar-specific sensitivity under indoor vertical farm conditions. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Other Status: Published Year Published: 2022 Citation: Kacira, M. 2022. Optimizing air distribution in CEA. Indoor AgScience Caf�, May.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kacira, M. 2022. Sustaining the future with precision horticulture and engineering focusing on resource use efficiency. Annual South Korean Society for Bio-Environment Control.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kacira, M. 2022. Innovative technologies for small-scale farmers. Food and Agriculture Organization of the United Nations & ISHS Joint Webinar.
• Type: Other Status: Published Year Published: 2022 Citation: Kelly, N. and E.S. Runkle. 2022. Biochemical and coloration analysis of red-leaf lettuce grown indoors under dynamic UV-A or blue light. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kelly, N. and E.S. Runkle. 2022 End of production UV-a or blue light similarly increase coloration and anthocyanin concentration of red-leaf lettuce. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Brewer, D. and R.G. Lopez. 2022. Quantifying the influence of blue or blue + red end-of-production sole-source lighting on red leaf lettuce (Lactuca sativa). American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Other Status: Published Year Published: 2022 Citation: Buelow, R., D. Johnson, E. Runkle, A. Tzes, and P. Wilford. 2022. Technology innovations for next generation solutions. Aerofarms AgTech Innovation Virtual Summit. Abu Dhabi, United Arab Emirates (webinar).
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Ertle, J.M. and C. Kubota. 2022. Nighttime dim lighting for indoor lettuce farm reduced stomatal resistance but not tipburn. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kelly, N. and E. Runkle. 2022. Lighting beyond PAR. OptimIA Annual Stakeholder Meeting, Univ. of Arizona, Tucson, AZ.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kohler, A.E. and E.S. Runkle. 2022. The photon spectrum and flux density of sole-source lighting affect growth and post-harvest performance of frill-leaf lettuce. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Krage, L., C. Kubota, K.C. Shasteen, M. Kacira, and S. Valle de Souza. 2022. Optimizing lettuce planting density in a shallow-water culture vertical system: Plant biomass accumulation, system productivity and produce quality in short-cycle production. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Other Status: Published Year Published: 2022 Citation: Kubota, C. 2022. Lettuce tip-burn basics. Indoor Ag Science Caf�, February.
• Type: Other Status: Published Year Published: 2022 Citation: Kubota, C. 2022. Other leafy greens: Microgreens and other greens. Japan Plant Factory Association Online Training Course on Plant Factories with Artificial Lighting, February.
• Type: Other Status: Published Year Published: 2022 Citation: Kubota, C. 2022 Why and why not harvesting lettuce crops early?  An integrated evaluation. Indoor Ag Science Caf�, August.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kubota, C., G. Papio, and J.M. Ertle. 2022. Technological overview of tip-burn management in vertical farming conditions. International Horticultural Congress, International Symposium on Advances in Vertical Farming, Angers, France.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Lopez, R.G. 2022. Greenhouse management of temperature and light in the production of leafy greens and vegetable transplants. Mid Atlantic Fruit and Vegetable Convention, Hershey, PA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Lopez, R.G. 2022. Management of temperature and light of leafy greens and vegetable transplants. Canadian Greenhouse Conference, Niagara Falls, Ontario, Canada.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Sheibani, F. and C. Mitchell. 2022. Close-canopy lighting: an approach to improve crop-canopy photon capture. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Sheibani, F., D. Camli-Sanders, E. Kennebeck, and C. Mitchell. 2022. Effect of far-red light on growth and canopy development of Rouxai baby lettuce at various harvest times and CO2 concentrations. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Other Status: Published Year Published: 2022 Citation: Peterson, H. C. and Valle de Souza, S. 2022, Consumer varieties for indoor farm produced leafy greens, Indoor Ag Science Caf�, April.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Runkle, E. 2022. Light quantity can attenuate effects of light quality. 2022 International Meeting Controlled Environment Technology and Use, Tucson, AZ.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Runkle, E. 2022. The science and practice of horticultural lighting. 17th International Symposium on Science & Technology of Lighting (LS:17), Toulouse, France.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Shasteen, KC, J. Seong, S. Valle De Souza, C. Kubota, and M. Kacira. 2022. Optimal planting density, effects on harvest time and yield. 2022 XXXI International Horticultural Congress: IHC2022, Angers, France.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Shin, J. and E. Runkle. 2022. Do photon spectrum and air temperature interact to determine leafy green yield and quality? OptimIA Annual Stakeholder Meeting, Univ. of Arizona, Tucson, AZ.
• Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Stallknecht, E., A.E. Kohler, and E.S. Runkle. 2022. Targeted applications of monochromatic blue light to increase lettuce yield and pigmentation. American Society for Horticultural Science Annual Conference, Chicago, IL.
• Type: Other Status: Published Year Published: 2022 Citation: Valle de Souza, S., J. Seong, A. Athnos, and H.C. Peterson. 2022. Comparative choice experiment with leafy green consumers. Nebraska Agricultural Economics Seminar Series, University of Nebraska-Lincoln, Lincoln, NE.
• Type: Theses/Dissertations Status: Published Year Published: 2022 Citation: Shasteen, KC. 2022. Developing phytometric feedback based decision support for optimizing vertical farm resource use efficiency. MSc Thesis, Biosystems Engineering Department, The University of Arizona. [Advisor: M. Kacira]
• Type: Theses/Dissertations Status: Published Year Published: 2022 Citation: Tarr, S.T. 2022. Improving yield and quality of leafy greens grown indoors with precise radiation, temperature, and carbon dioxide management. MSc Thesis, Department of Horticulture, Michigan State University. [Advisor: R.G. Lopez]

Progress 09/01/20 to 08/31/21

Outputs
Target Audience:Our target audience consists of indoor (vertical) farming growers and operators, venture capital investors, research and development personnel for indoor farming equipment, greenhouse growers, indoor farming consultants, agricultural and mechanical engineers, university faculty and extension personnel, and undergraduate and graduate students. Changes/Problems:The COVID-19 pandemic continued to hamper our project progress, although not to the extent as the previous year. We postponed on-site visits to stakeholder farms and delayed the onset of coordinated grower trials. This delayed collection of economics data and interviews became significantly more difficult because industry participants no longer had availability to meet. Another limitation of economics data collection is industry reluctance to share their economic data for modelling and research purposes. This is forcing the team to expand data collection beyond the US domestic industry. Purdue encountered lingering issues related to non-uniformity of intensity and spectral distribution of light at close separation distances with the LED lighting units used for the close-canopy lighting research. What opportunities for training and professional development has the project provided?At OSU, two graduate students and two undergraduate students were engaged in, and supported by, this project. One student (Papio) completed his MS program in Aug. 2021 and is currently an assistant grower for a leafy greens production company. Another student (Ertle) continued his PhD program (since August 2020) and passed his candidacy exam in Aug. 2021. Two undergraduate students assisted the two graduate students and learned about growing leafy greens in controlled environments. At Arizona, two graduate students have been involved in this project. MS candidate Shasteen evaluated how various environmental variables (including daily light integral, air temperature, and CO2 concentration) influence lettuce yield. He also participated in the modeling group meetings and gained experience in the planning, designing, and conducting of scientific experiments in controlled environments. Another student (Kaufmann) started an MS program in Sept. 2021. In the Department of Horticulture at MSU, two MS and two PhD students, and two undergraduate students, performed indoor leafy greens research for this project. They were assisted by research technician Durussel, who assisted with experimentation. MS students Tarr started in spring of 2020 and Brewer in fall of 2021, and they are performing research and outreach activities related to accomplishing Objectives 2C and 3. PhD students Kelly started in fall of 2019 and Shin in fall of 2021, and they are executing experiments needed to address Objectives 2B and 2C. All students are learning about and gaining experience with experimental planning and design; data collection, analysis, and interpretation; synthesis of results; and communicating information to grower and scientific audiences. They also received responsible conduct of research training. In the Department of Agricultural, Food, and Resource Economics at MSU, two graduate students participated in this project. PhD student Seong has been working with the team for two years having participated directly in all research and outreach activities of the project, including secondary data collection and analysis, and the design and distribution of a survey followed by data analysis and manuscript writing. PhD student Oh was equally involved in all activities. Both students presented their results to industry partners during our economics committee meetings, during which they actively participated in discussions about issues that are relevant to this industry. At Purdue, PhD graduate student Sheibani was supported by this project. She participated in the American Society for Horticultural Conference annual conference and networked with conferees, asked questions, and made comments about presented research. She gained knowledge and perspective from current advances in indoor agriculture. In addition, she gained valuable experience mentoring undergraduate engineering technology and life sciences students who provided research assistance or conducted their own guided research projects. How have the results been disseminated to communities of interest?We coordinated a monthly Indoor Ag Science Café forum (www.scri-optimia.org/cafe.php) and continued to develop our project website (www.scri-optimia.org). Most of the Café webinars were recorded and are publicly available on the project website. Research results and project activities have been shared with different industry and academic audiences including the following meetings and conferences: All team members presented research and outreach updates at the second annual stakeholder meeting held in a hybrid online and in-person format in Columbus, OH. The American Society for Horticultural Science Annual Conference held in a hybrid format in Denver, CO. The American Society of Heating, Refrigerating and Air-Conditioning Engineers annual conference held in an online format. The Univ. of Arizona Greenhouse Engineering and Crop Production Short Course held in an online format. The IX International Symposium on Light in Horticulture held in Sweden in an online format and under the auspices of the International Society for Horticultural Science. Members of the NE-1835 (Resource Optimization in Controlled Environment Agriculture) working group in an online format. The economics team (led by Valle de Souza at MSU) presented preliminary results from survey analysis to industry partners in four meetings. These two-hour long meetings included a presentation of results in the first hour followed by discussions. Feedback from these partners contributed to shape further research developments. For example, the project is now encompassing further studies on indoor agriculture labor to provide advice on current workforce issues faced by the industry. What do you plan to do during the next reporting period to accomplish the goals?Kacira's team (Arizona) will continue experiments with various environmental variables to collect data on biomass yield and use computational fluid dynamics modeling to evaluate air flow uniformity in indoor vertical farm systems. They will collaborate on the economic model development and further validate and evaluate crop growth models to be used in co-optimization of environmental variables and cost savings. They also will continue developing methods with experimental measurements and modeling to quantify crop transpiration and water use to improve water vapor management in indoor vertical farming systems. Kubota's team (OSU) will continue working on developing simple models to assess potential growth rate of lettuce crops to use in the tipburn assessment. They will also define highly inducive and preventative conditions (combinations of light, water vapor pressure deficit, air flow, carbon dioxide concentration, and temperature) based on these assessments. They will work with indoor farms to help them assess their microclimate conditions using the developed tools. They will continue examining cultivar-specific tipburn sensitivities working with seed companies and begin developing strategies to prevent tipburn based on our understanding of inducive and preventive conditions. Lopez's team (MSU) will combine all the environmental and cultural data generated from previous OptimIA studies to optimize lettuce growth and development under white LEDs. Given that anthocyanin production in red-leaf lettuce is not maximized under white light, plants will be exposed to end-of-production lighting containing blue light alone or in combination with red light. Anthocyanins, phytonutrients, tip-burn incidence, consumer preference, and post-harvest shelf life will be quantified to determine which treatments produce the highest quality lettuce. Mitchell's team (Purdue) will perform replicated experiments that compare close-canopy lighting (CCL) strategies and then publish results and conclusions. They will generate gas-exchange patterns of CO2 and light dose-response curves for baby and leafy greens and will investigate a targeted lighting strategy to save energy in production of leafy greens. The findings of targeted lighting strategy will be a guidance toward next-generation LED system design. They will also continue investigating phasic optimization of lighting considering energy, timing, and CO2 enrichment, and other resources. In addition, they will investigate the synergistic effect of different CO2 / light combinations as a function of various red / far-red ratios. The results of CCL will lead to closer collaboration with project colleagues, and will be integrated into models they are developing, such as closer vertical distances between LEDs and crop surface, which may affect airflow within indoor-growing designs. Runkle's team (MSU) will work towards publishing the results of two experiments completed during this project period. Additionally, they will complete a study that evaluates plant growth under different shades of white LEDs. Finally, two more experiments are planned for the next reporting period. The first will investigate the effects of enriched blue light delivered early during production on growth and quality of lettuce. The second study will further investigate the role of far-red light in driving photosynthesis and plant growth. Valle de Souza's team (MSU) will collect further primary and secondary data through retailer surveys, industry field trips, and interviews and research. This will provide information about the supply chain, and input from farm operations will be incorporated to the profit optimization model. Results from Objective 2 will also be incorporated to the model. Additional data will be collected from a labor survey. Team members will publish a series of articles in a grower magazine that will include frequently asked questions about indoor farming. This information will then be posted on the OptimIA project website. In addition, Runkle (MSU) will publish a series of articles in a grower magazine that summarizes findings from specific lighting experiments with indoor production of leafy greens. The team will also coordinate and host an annual stakeholder meeting, expand their project website, and continue the Indoor Ag Science Café webinar series. Finally, team members will participate in the Greenhouse Lighting and System Engineering (GLASE) Short Course, which will include lighting inside indoor farms.

Impacts
What was accomplished under these goals? Objective 1A: Valle de Souza (Michigan State University; MSU) analyzed primary survey data that produced estimates of consumers' willingness to pay for attributes. This information will used in the market demand section of the optimization model and inform preferred attributes to be targeted by the profit optimization model. Objective 1B: The modeling working group completed the baseline framework for energy, water, carbon dioxide, labor input/output models, as well as growth/yield models. For example, they developed core model equations for estimating electrical energy consumption as affected by lighting conditions, light fixture efficacy, and energy consumption by air conditioning systems. These models will be used for site-specific operational cost and productivity analyses. Working group members also provided intensive feedback for the consumer survey developed by Valle de Souza. Objective 1C: Valle de Souza (MSU) continued progress with the development of the proposed mathematical model describing optimal profitability relationships among capex, opex, and revenue generated by indoor producers of leafy greens. Objective 2A: Mitchell (Purdue) developed experimental protocols using their indoor experimental setup. These protocols included procedures for preparing media-based growing systems and fertigation schedules, environmental-parameter adjustment, and lighting recipes. These protocols have been optimized for close-canopy light and will continue to be adapted during the project when necessary. Objective 2A: Mitchell (Purdue) optimized a gas-exchange system and calibrated its components to assure the accuracy of output data. They developed experimental protocols for its maintenance, calibration, and operation and had productive input from Li-Cor about crop photosynthesis calculations. Objective 2B: Runkle (MSU) collected lettuce tissue samples under various indoor LED lighting treatments delivered in multiple studies. They completed nutritional analysis of those samples to determine the effects of light quality, especially blue and UV-A light, on specific phytochemicals. Objective 2B: Runkle (MSU) completed an experiment that investigated how light intensity and light quality interact to influence plant biomass and quality, including leaf color and size and concentrations of different secondary metabolites. Data collection and biochemical analysis for this experiment are complete. Objective 2C: Kubota (Ohio State University; OSU) developed a simple tool using petri dishes to assess potential transpiration rate inside indoor farms as affected by microclimate conditions. To test the efficacy of such a tool, growth chamber experiments were conducted to determine its sensitivity to light intensity, water vapor-pressure deficit, and air speed. Increasing light absorptance of water by adding black food coloring improved the tool's response to light intensity. In addition to a standard petri-dish, a deep-dish tool was evaluated for its reduced sensitivity to horizontal air flow, comparing that to vertical air flow, which has a distinctly different impact on tipburn control. When used in tandem, the petri/deep-dish tools could effectively assess the spatial microclimatic non-uniformity causing differences in potential transpiration rates inside narrow head-spaced areas of leafy green production systems. Objective 2C: Kubota (OSU) grew nine lettuce cultivars considered as relatively sensitive to tipburn 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 a breeding program (open field and greenhouse). Greenhouse cultivars were relatively less sensitive and exhibited lower tipburn incidence than did open-field cultivars when grown under tipburn-inducive indoor growing conditions. Cultivar type did not show a significant effect on tipburn sensitivity. Objective 2C: Kacira (Arizona) conducted experiments with lettuce grown under different daily light integrals and air temperatures, with dynamic control of CO2 during growing stages. The data obtained from these experiments serve as input variables for crop growth model validation studies, which contributes to our efforts in Objectives 1B, 1C, and 2C. Objective 2C: Lopez (MSU) conducted a series of experiments to quantify the effects of light intensity, day and night temperature, and carbon dioxide concentration on lettuce biomass, color, and quality. Objective 3: Led by Kubota (OSU), our project team organized 11 forums for the Indoor Ag Science Café during the reporting period, with speakers from both industry and academia. Team members also authored scientific publications and industry-focused articles, and delivered presentations to a range of academic and industry audiences.

Publications

• Type: Journal Articles Status: Published Year Published: 2021 Citation: Gillespie, D.P., G. Papio, and C. Kubota. 2021. High nutrient concentrations of hydroponic solution can improve growth and nutrient uptake of spinach (Spinacia oleracea L.) grown in acidic nutrient solution. HortScience 56:687-694.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Kohler, A.E. and R.G. Lopez. 2021. Daily light integral influences rooting of herbaceous stem-tip culinary herb cuttings. HortScience 56:432-438.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Meng, Q. and E.S. Runkle. 2020. Growth responses of red-leaf lettuce to temporal spectral changes, Frontiers in Plant Science 11:571788.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Montoya, A.P., F.A. Obando, J.A. Osorio, J.G. Morales, and M. Kacira. 2020. Design and implementation of a low-cost sensor network to monitor environmental and agronomic variables in a plant factory. Computers and Electronics in Agriculture, 178:105758.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Vaatakait?-Kairien?, V., N. Kelly, and E.S. Runkle. 2021. Regulation of the photon spectrum on growth and nutritional attributes of baby-leaf lettuce at harvest and during postharvest storage. Plants 10(3):549.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Walters K.J. and R.G. Lopez. 2021. Modeling growth and development of hydroponically grown dill, parsley, and watercress in response to photosynthetic daily light integral and mean daily temperature. PLOS ONE 0248662.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Walters, K.J., R.G. Lopez, and B.K. Behe. 2021. Leveraging controlled-environment agriculture to increase key basil terpenoid and phenylpropanoid concentrations: The effects of radiation intensity and CO2 concentration on consumer preference. Frontiers in Plant Science 11:1-12.
• Type: Other Status: Published Year Published: 2021 Citation: Kacira. M., P.-E. Bournet, L.R. Khot, Q. Yang, I.L. Cruz, W. Luo, H.J. Schenk, H. Fatnassi and Lopez, R. 2021. ISHS Division Precision Horticulture and Engineering: sustaining the future with precision horticulture and engineering. Chronica Horticulturae 61(2):17?20.
• Type: Other Status: Published Year Published: 2021 Citation: Lopez R.G. and C. Garcia. 2021. Culinary herbs: To flower or not to flower? Produce Grower Feb.:20-24.
• Type: Other Status: Published Year Published: 2021 Citation: Meng, Q. and E. Runkle. 2021. LEDs on lettuce: White light vs. red+blue light. Produce Grower June:24-28.
• Type: Other Status: Published Year Published: 2021 Citation: Runkle, E. 2021. Light fixtures and their photon fluxes. Greenhouse Product News 31(5):58.
• Type: Other Status: Published Year Published: 2021 Citation: Runkle, E. 2021. More than �mol�J1. Greenhouse Product News 31(7):42.
• Type: Other Status: Published Year Published: 2021 Citation: Runkle, E. 2021. Purpling of leaves. Greenhouse Product News 31(1):50.
• Type: Other Status: Published Year Published: 2021 Citation: Walters, K.J. and R.G. Lopez. 2021. Culinary herbs: Balancing light and average daily temperature. Produce Grower Aug.:18-21.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Kacira, M., K.C. Shasteen, and N. Sabeh. 2021. Environmental controls and resource use optimization. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Kacira, M. 2021. Modeling airflow in an indoor plant environment (panel member). ASHRAE Annual Conference: Up, Down, and All Around.
• Type: Other Status: Published Year Published: 2021 Citation: Kacira, M. 2021. Optimizing resource use efficiency in CEA systems. GLASE webinar series.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Kubota, C., G. Papio, and J. Ertle. 2021. Research update on environmental risk assessment and mitigation strategies for lettuce tip-burn. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Lopez, R.G. 2021. Tips for producing high-quality, non-flowering and flavorful culinary herbs by manipulating light, CO2 and temperature. Northeast Greenhouse Conference.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Lopez, R.G. 2021. Basics of producing culinary herbs and vegetable transplants achieving transplant uniformity. Cultivate On Demand, Columbus, OH.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Lopez. R.G. 2021. Achieving vegetable transplant uniformity. Connecticut Vegetable Transplant Production in Greenhouses Webinar Series.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Lopez, R.G. 2021. Temperature and radiation intensity influence growth and quality of red and green lettuce. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Meng, Q. and E.S. Runkle 2021. Blue photons in broad spectra determine lettuce yield, morphology, and color. American Society for Horticultural Science Annual Conference, Denver, CO.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Mitchell, C. and F. Sheibani. 2021. Reducing energy use in baby greens production. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Papio, G. and C. Kubota. 2021. Developing a microclimate assessment tool using simple dishes to evaluate potential transpiration in indoor farms. American Society for Horticultural Science Annual Conference, Denver, CO.
• Type: Other Status: Published Year Published: 2021 Citation: Runkle, E. 2021. Do we need green light in a vertical farm? International Society for Horticultural Science Talks on Vertical Farming.
• Type: Other Status: Other Year Published: 2021 Citation: Runkle, E. 2021. Indoor farming of leafy greens. NSF-sponsored Convergence Accelerator online workshop: Sustainable Systems Enabling Food Security in Extreme Environments and Food Deserts employing a Convergence of Food, Energy, Water and Systems.
• Type: Other Status: Other Year Published: 2021 Citation: Runkle, E. 2021. Lighting of specialty crops grown indoors. Department of Horticulture & Landscape Architecture seminar series, Purdue University, West Lafayette, IN.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Runkle, E. and N. Kelly. 2021. Phasic and end-of production blue and UV-A lighting. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Runkle, E. 2021. Fundamentals on supplemental and sole-source lighting for controlled-environment agriculture. Controlled-Environment Agriculture Short Course, University of Arizona, Tucson, AZ.
• Type: Other Status: Other Year Published: 2020 Citation: Runkle, E. 2020. Whats new and exciting about plant lighting. Michigan State University Plant Trial Field Day, East Lansing, MI.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Sheibani, F. and C. Mitchell. 2021 Close-canopy LED lighting as an energy-efficient and/or yield-enhancing lighting strategy for indoor production of baby greens. American Society for Horticultural Science Annual Conference, Denver, CO.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Sheibani, F. and C. Mitchell. 2021. CO2 and light photosynthetic dose-response profiles for baby-green and leafy-green stages of Rouxai lettuce production. American Society for Horticultural Science Annual Conference, Denver, CO.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Tarr, S. and R.G. Lopez. 2021. Quantifying the influence of increasing day and night temperature and carbon dioxide concentration on growth and development of red and green lettuce (Lactuca sativa). American Society for Horticultural Science Annual Conference, Denver, CO.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Tarr, S. and R.G. Lopez. 2021. Quantifying the influence of day and night temperature, radiation intensity, and carbon dioxide concentrations on regulating growth and quality attributes of red and green lettuce (Lactuca sativa). 2021 IX International Symposium on Light in Horticulture, Malm�, Sweden.
• Type: Other Status: Other Year Published: 2021 Citation: Tarr, S., R. Lopez, N. Kelly, and E. Runkle. 2021. Fresh greens year-round inside your home: Learn how to grow your own leafy greens hydroponically. MSU Science Festival, East Lansing, MI.
• Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Valle de Souza, S., J. Seong, and C. Peterson. Economics and consumer research update. OptimIA Research Collaborative Update, Ohio State University, Columbus, OH.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Walters, K.J. and R.G. Lopez. 2021. The influence of light intensity and carbon dioxide concentration during seedling production on dill, parsley, and sage growth and development at harvest. 2021 IX International Symposium on Light in Horticulture, Malm�, Sweden.
• Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Papio, G. 2021. Development of a new hydroponic nutrient management strategy and a tool to assess microclimate conditions in indoor leafy green production. MS thesis, the Ohio State University.
• Type: Websites Status: Published Year Published: 2021 Citation: OptimIA: Optimizing Indoor Agriculture for Leafy Green Production. http://www.scri-optimia.org.

Progress 09/01/19 to 08/31/20

Outputs
Target Audience:Our target audience consists of indoor farming growers and operators, venture capital investors, R&D personnel for indoor farming equipment, greenhouse growers, indoor farming consultants, agricultural engineers, university faculty and extension personnel, and undergraduate and graduate students. Changes/Problems:The COVID-19 pandemic caused major delays in experimentation and data collection because of imposed work and travel restrictions. In many cases, we had to terminate experiments in March 2020, and could not resume research until June or July 2020. Field trips (including visits with industry stakeholders) were completely suspended, and interviews became significantly more difficult because industry participants no longer had availability to meet. This has caused delays in data collection and project development goals, and reduced industry collaboration. What opportunities for training and professional development has the project provided?At Ohio State University (OSU), two graduate students are zealously engaged in this project. One student started his MS program in the fall of 2019 and is performing research related to accomplishing parts of Objective 2C. A new graduate student started in the fall of 2020 and is currently setting up research facilities for conducting his experiments also related to Objective 2C. Both students have been gaining experiences of planning, designing, and conducting scientific experiments in controlled environments. While COVID-19 limited our research activity for several months, the graduate students worked on their literature reviews, which expanded their research background. In the Department of Horticulture at Michigan State University (MSU), one MS and one PhD student, two undergraduate students, and a research technician nimbly performed indoor leafy greens research for this project. The MS student started in the spring of 2020 and is performing research and outreach related to accomplishing Objectives 2C and 3. The PhD student started in the fall of 2019 and is executing experiments needed to address Objectives 2B and 2C. Both students are learning about and gaining experience with experimental planning and design; data collection, analysis, and interpretation; and synthesis of results. The COVID-19 pandemic hampered research activity for several months, but the graduate students worked on other items such as development of a thesis proposal, literature review, and review article. They also received responsible conduct of research training. This project has provided opportunity for training a PhD student in the Department of Agricultural, Food, and Resource Economics at MSU. The student has participated in weekly meetings with the economics team, bi-weekly meetings with the model development team, ad hoc meetings with industry and scholars, and all three field visits to indoor farms. He has developed the framework for the retailer and consumer survey, and has taken part in the worksheet model, as well as in the optimization model development. At Purdue, a PhD graduate student involved in the project is enthusiastically learning the basics of controlled-environment agriculture, the use of computer-based technology to drive and monitor the inputs and outputs of CEA, and the development of such technology, the latter by working with advanced undergraduate engineering technology students. The engineering technology students are cited on publications, and in some cases are included as co-authors for creative efforts enabling such publications. The PhD student also has worked with programmers to custom-develop software that is enabling current research and data acquisition. As well, an undergraduate researcher has benefitted from participating in a related internship at the NASA Kennedy Space Center during the reporting period and has begun an experimental capstone project on CO2 enrichment of baby greens that will come to fruition during the forthcoming reporting period. At Arizona, two graduate students have been engaged in this project. A PhD student performed computational fluid dynamics modeling to evaluate air flow uniformity in indoor vertical farm systems related to research activities in Objective 2D. An MS student has been evaluating various environmental variables including daily light integral, air temperature, and CO2 concentration for biomass yield. The MS student has been also involved in bi-weekly modeling group discussion meetings. Both students have been gained experiences of planning, designing, and conducting scientific experiments in controlled environments. COVID-19 has limited our research activities and timelines for several months, however graduate students have focused on literature reviews, analysis of some of the existing data, and experimental designs. How have the results been disseminated to communities of interest?We hosted our first annual stakeholder meeting in July, 2020 in an online format. A total of 190 people registered, including indoor farmers, indoor farming suppliers, academics, government scientists, and private consultants from throughout the US as well as several northern and eastern European countries. All project co-PIs discussed current research projects and in some cases, shared preliminary research results. We coordinated a monthly Indoor Ag Science Café forum (http://www.scri-optimia.org/cafe.php) and developed our project website (http://www.scri-optimia.org). The Café webinars were recorded and are publically available on the project website. Research results and project activities have been shared with different industry and academic audiences including: The ASHS Annual Conference The ISHS VertiFarm 2019: International Workshop on Vertical farming The Arizona-CEAC Greenhouse Engineering and Crop Production Short Course Members of the NE-1835 (Resource Optimization in Controlled Environment Agriculture) working group Members of the NCERA-101 (Committee on Controlled Environment Technology and Use) working group What do you plan to do during the next reporting period to accomplish the goals?Arizona will continue experiments with various environmental variables including daily light integral and air temperature to collect data on biomass yield of lettuce; perform computational fluid dynamics modeling to evaluate air flow uniformity in indoor farming systems; and collaborate on the economic model development and further validate and evaluate crop growth models to be used in the co-optimization of environmental conditions. They will also continue working on developing methods with experimental measurements and modeling of crop transpiration and water use to improve humidity management in indoor farming systems. OSU will finalize the baseline protocols to assess microclimates for potential transpiration rate to use in the tipburn assessment for lettuce; continue working on developing simple models to assess potential growth rate of lettuce crop to use in the tipburn assessment; and begin to define highly inductive and preventative environmental conditions for tip-burn. OSU will also work with indoor farms to assess their microclimate conditions using the developed tools, examine cultivar-specific tip-burn sensitivities working with seed companies, and examined humidity management strategies at night to mitigate tipburn incidence. Economists at MSU will collect primary and secondary data through retailers' and consumers' surveys, industry field trips (when travel restrictions are lifted) and interviews, and research. Surveys will provide information about the supply chain, preferred attributes, and willingness to pay for leafy green attributes. Data will be incorporated to the profit optimization model. Results from Objective 2 will also be incorporated to the model. Further data will also be collected for defining labor availability in America, incurring costs, and its impact on indoor farming profitability. MSU will perform experiments to estimate the base, optimum, and maximum temperature for leaf unfolding of lettuce, arugula, and kale. Plants will be grown at a range of constant temperatures from 7 to 32 °C (45 to 90 °F) with controlled humidity and a constant daily light integral. MSU will also quantify how carbon dioxide concentration, light intensity and temperature interact to influence growth and quality of red- and green- leaf lettuce. Environmental conditions will include temperatures ranging from an average daily temperature of 20 °C (68 °F) to 26 °C (79 °F), two light intensities, and elevated carbon dioxide concentration. Additional research will be performed to determine how humidity interacts with increasing light intensity at high temperatures and carbon dioxide concentration to influence growth, quality, and tip burn of lettuce. MSU will also conduct nutritional analyses of crops grown, harvested, and freeze dried from plant growth experiments performed during the first project year. A new experiment will also be performed to quantify and compare how light quality and light quantity affect secondary metabolite/vitamin biosynthesis and coloration of red- and green-leaf lettuce. Plants will be grown under warm-white LEDs with enriched at two levels with blue, green, red, and far-red light. Effects on yield, nutrition, and coloration will be quantified. Data will be collected, analyzed, and interpreted, and publications will be drafted for both grower and scientific audiences. Purdue will grow different baby green species, including lettuce and mizuna mustard, at four different lamp-crop separation distances, from 40 to 10 cm. The reference photosynthetic photon flux density (light intensity) at 40 cm will be 200 µmol/m2s. As lamps are brought increasingly closer to plant surfaces in subsequent experiments, LEDs will either be dimmed to maintain light intensity at plant level, or they will be kept at constant power and light intensity will increase at closer separation distances. Energy for lighting will be monitored and logged throughout periods when LEDs are energized, and harvest productivity will be rated on a crop bio-mass/energy-cost basis. Next, Purdue will begin the first stage of phasic-optimization studies, focusing first on the lag phase of seedling development, which typically constitutes the majority of cropping time for baby greens. They will determine when seedlings first become photosynthetically competent, when the lag phase of development ends, when the exponential phase begins, and what is the best time to harvest, based upon seedling size, crop-canopy limitations, and responsiveness to environmental treatments. Results will be used to develop lighting and cropping recipes that save maximum energy and resources for baby-greens production. Once travel restrictions by our universities have been lifted, and it is safe to travel, we will resume visits to some of our indoor farm cooperators. We also hope that our next annual meeting, as well as advisory committee meeting, can be held in person to facilitate better networking and idea exchange. We will continue to deliver information generated from our project at grower/industry meetings and conferences, as well as at scientific venues, and further develop our project website. We will continue to host monthly Ag Science Café webinars and discussion forums, and hope to obtain even greater input from growers on specifics related to planned research.

Impacts
What was accomplished under these goals? Objective 1A: We collected primary and secondary data directly from industry members through interviews and indoor farm visits. Secondary data were collected from publicly available industry reports, academic journal articles, and media sources. Objective 1B: The modeling working group began meeting every two weeks to develop the framework for energy, water, and CO2 input/output models. These models will be used for site-specific operational cost and productivity analyses. During the reporting year, we also developed core model equations for estimating electrical energy consumption as affected by factors such as lighting efficiency and lamp efficiency. Objective 1C: Data collected allowed for the development of an initial spreadsheet model defining the economic structure of indoor farms, which allowed for detailed discussions with industry members and academic colleagues regarding significant factors affecting profitability of indoor farms in the U.S. This model and feedback received is now being used in the development of the proposed mathematical model describing optimal profitability relationships among capex, opex, and revenue generated by indoor producers of leafy greens. Objective 2: Many team members developed their experimental controlled-environment facilities that will be used to perform experiments throughout the project. In some cases, their research capabilities expanded and new lighting systems were employed. Systems are now fully established and functional, and useful experimental data collection has begun. Objective 2B: We preformed experiments with low-cost warm white LEDs that were supplemented with additional UV-A and blue light with the goal of increasing nutrient content and shelf life. Data were collected on a variety of physical attributes including fresh weight, leaf color, and leaf size. Tissues have been prepared for future nutrient analysis. Objective 2C: We conducted a series of experiments to quantify the effects of light intensity, day and night temperature, and carbon dioxide concentration on lettuce biomass, color, and quality. We developed a simple tool to assess potential transpiration rate as affected by microclimate conditions. Taking the advantage of relatively stable controlled environments in indoor farms, we tested a petri-dish based assessment tool for potential transpiration. We conducted experiments with lettuce grown under three daily light integrals. Average fresh biomass yields in 28-day production period after transplanting were collected. The data obtained from these experiments serve as input variables for crop growth model validation studies, which will help with our efforts in Objectives 1B, 1C, and 2C. We developed a computational fluid dynamics model and evaluated five design configurations with air ventilation systems in an indoor plant factory for uniformity of the environment based on air temperature, vapor pressure deficit, and air current speed over the crop canopy. Case 1 is the control, with a typical mixing system producing entrainment flow. Case 2 has inlets and outlets placed in alternating rows on the ceiling. Case 3 has outlets on the bottom of two side walls. Case 3 has the same size and location of inlets as in Case 2, but outlets are placed on two side walls close to the floor. Case 4 supplies conditioned air with perforated tubes installed above aisles and returned air flow exhausted from the ceiling. Case 5 has perforated air tubes installed at each level of shelves to provide localized horizontal air flow over the crop canopy and outlets on the ceiling. For climate uniformity, Case 5 performed the best. Objective 3: We organized 11 Indoor Ag Science Café webinars and discussion forums during the reporting period, with speakers from both industry and academia. We also developed a project website and are coordinating the development of short research articles for public distribution. Team members continue to interact with members of the Advisory Board and industry stakeholders.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Gillespie, D.P., C. Kubota, and S. Miller. 2020. Effects of low pH of hydroponic nutrient solution on plant growth, nutrient uptake, and root rot disease incidence of basil (Ocimum basilicum L.). HortScience 55:1251-1258.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Kelly, N. and E.S. Runkle. 2020. Spectral manipulations to elicit desired quality attributes of herbaceous specialty crops. Eur. J. Hortic. Sci. 85:339-343.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Kelly, N., D. Choe, Q. Meng, and E.S. Runkle. 2020. Promotion of lettuce growth under an increasing daily light integral depends on the combination of the photosynthetic photon flux density and photoperiod. Sci. Hort. (article 109565).
• Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Mitchell, C. 2020. An early history of indoor agriculture. HortScience (In press).
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Walters, K.J., B.K Behe, C.J. Currey, and R.G. Lopez. 2020. Historical, current, and future perspectives for controlled environment hydroponic food crop production in the United States. HortScience 55:758767.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Zhang, Y. and Kacira, M. 2020. Enhancing resource use efficiency in plant factory. Acta Hortic. 1271:307-314.
• Type: Other Status: Published Year Published: 2020 Citation: Runkle, E. 2020. LED fixture efficacy: A 2020 update. Greenhouse Product News 30(1):50.
• Type: Other Status: Published Year Published: 2020 Citation: Runkle, E. 2020. What is the ideal lighting spectrum? Greenhouse Product News 30(3):42.
• Type: Other Status: Published Year Published: 2020 Citation: Walters, K.J. and R.G. Lopez. 2020. Indoor production of herb seedlings: Light intensity and carbon dioxide. Produce Grower (Dec.):20-24.
• Type: Other Status: Published Year Published: 2019 Citation: Walters, K.J. and R.G. Lopez. 2019. Lighting basil seedlings. Produce Grower (Apr.):28-32.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Amitrano, C., V. De Micco, G. B. Chirico, Y. Rouphael, S. De Pascale, KC Shasteen, M. Kacira. 2020. Application of the energy cascade model (MEC) on lettuce crop grown in controlled environment agriculture at two different scales: A small growth chamber and a vertical farm. MELISSA 2020 Virtual International Conference.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Kacira, M. 2020. Sensors and environmental controls in indoor vertical farming. 2020. Hands-on workshop at 9th Annual Greenhouse Engineering and Crop Production Short Course, Tucson, Arizona.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Kacira, M. 2019. Climate control in vertical farming. ISHS VertiFarm 2019: Workshop on Vertical Farming, Wageningen, the Netherlands.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Papio, G. and C. Kubota. 2020. Raising concentration of hydroponic nutrient solution improves spinach plant growth in low pH solution. ASHS Annual Conference.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Runkle, E. 2019. Spectral manipulations to elicit desired plant quality attributes. ISHS VertiFarm 2019: Workshop on Vertical Farming, Wageningen, the Netherlands.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Runkle, E. 2020. Lighting of horticultural crops grown indoors. ASHS webinar.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Sheibani, F., Z. Yu, A. Clemente, C. McDonnel, and C. Mitchell. 2020. Monitoring the dynamics of leafy vegetable production in real time with the Minitron III crop-growth/gas-exchange system (poster presentation). ASHS Annual Conference.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Stallknecht, E., Q. Meng, and E.S. Runkle. 2020. Phasic lighting strategies to improve indoor lettuce production. ASHS Annual Conference.
• Type: Websites Status: Published Year Published: 2020 Citation: OptimIA: Optimizing Indoor Agriculture for Leafy Green Production. http://www.scri-optimia.org.