Source: UNIVERSITY OF GEORGIA submitted to
OPTIMIZING THE COST-EFFECTIVENESS OF LIGHTING IN CONTROLLED ENVIRONMENT AGRICULTURE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
EXTENDED
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1016320
Grant No.
2018-51181-28365
Project No.
GEOW-2018-03402
Proposal No.
2018-03402
Multistate No.
(N/A)
Program Code
SCRI
Project Start Date
Aug 1, 2018
Project End Date
Jul 31, 2024
Grant Year
2020
Project Director
Ferrarezi, R. S.
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
HORTICULTURE RESEARCH COLLEGE
Non Technical Summary
The US greenhouse industry, including floriculture and greenhouse vegetables, had a 2015 farm gate value of ~$6.5 billion. In greenhouses, most environmental variables can be controlled to provide optimal conditions for plant growth. Light typically is less controlled than other environmental conditions, which can result in significant variability in light levels and thus crop yield and quality. The variability can be spatial, spectral, and temporal and occurs on short (within a day), intermediate (day-to-day), and long (seasonal) time scales. For efficient year-round production in greenhouses, supplemental light is often beneficial, but the expenses can be high. The electricity required for supplemental lighting in greenhouses accounts for 20-30% of variable costs. Since typical greenhouse profit margins are 1-5%, more cost-effective lighting strategies can have a major impact on the profit margin. Plant factories, an emerging technology where plants are grown indoors, provide total control over environmental conditions, but production relies entirely on electric lighting, accounting for 50-60% of the variable costs. Clearly, more cost-effective lighting approaches will have a major impact on the sustainability and profitability of controlled environment agriculture (greenhouses and plant factories), reduce energy use and greenhouse gas emissions, and thus also provide societal and environmental benefits.There has been little past research on optimizing the economic return of supplemental lighting practices for greenhouse production (floriculture and vegetables) and most past work has focused on high-pressure sodium (HPS) lights. Light-emitting diode (LED) lights are gradually becoming cheaper and more efficient, and are increasingly being used instead of HPS lights. However, LED lights are more expensive to install than HPS lights, so to justify the capital expense, LED lights need to provide additional value compared to HPS. That value can come from lower operating costs, higher yields, better quality, or the production of higher value specialty crops.LED lights provide important new opportunities to increase the cost-effectiveness of lighting, because both the spectrum and light intensity can be accurately controlled. This can give growers better control over crop growth and quality. However, current LED grow lights do not take advantage of the ability to precisely control light intensity and spectrum in real time. We will help growers get more value out of their lighting system by providing horticultural and economical information and tools to manage the lights for optimal crop growth and quality.The electrical cost associated with lighting often is the second largest variable cost in greenhouses after labor, and are the biggest cost in plant factories. Increasing the cost-effectiveness of lighting will lower production costs and/or increase the value of the crop (by increasing quality or yield), which can increase the margins and profitability of controlled environment agriculture.We will help growers make better lighting decisions. Specifically, we will: 1) develop tools to determine whether supplemental lighting is cost-effective for different locations and production systems, 2) decide whether HPS or LED lights are more cost-effective for a given application, and 3) develop guidelines to help growers get the most value out of supplemental lighting by minimizing operating costs and/or maximizing crop quality. We will develop models that consider crop physiological parameters, crop value, the design and capital costs of the lighting system, real-time electricity pricing, and current and forecasted light levels. These models will be used to develop strategies to provide supplemental light in the most cost-effective way possible. We will also develop hardware and software tools to help growers implement these lighting strategies, based on crop needs and specific growing systems. The return on investment of these lighting strategies will be evaluated to determine the cost-effectiveness of supplemental lighting.A comprehensive outreach plan will ensure that project findings are disseminated in different forms to reach the growers and associated CEA industries. Outreach efforts will include a website, webinars, presentations, online articles, trade journal articles, Extension visits and peer-reviewed journal articles. Industry members will be surveyed to determine how they prefer to receive information, allowing us to fine-tune our outreach methods. Beyond simply sharing research results, the decision-making tools we develop will directly assist industry members and allow direct implementation of these research results. We will develop decision support software to enable growers to assess whether use of supplemental lighting (and to what degree) is economical, given their crops and geographic location. If lighting is deemed profitable, the tools can be used to determine whether HPS or LED lights are more cost-effective based on the type of facility, patterns of lighting use, and electricity cost. Virtual Grower, a freely-available USDA-ARS greenhouse simulation tool, will be upgraded to include simulations of different lighting scenarios. These tools will be available on-line, with instructions and recorded webinars explaining how to use them. We also will develop software and controllers for growers to implement cost-effective lighting strategies, based on our research findings. These tools will help drive industry adoption of energy-efficient, cost-effective lighting technologies.Collaboration with lighting companies will be critical to the success of the project and these companies will be invited to our annual project meetings to provide feedback on project progress and direction. But more importantly, sharing our latest research findings with lighting companies will allow them to improve the functionality of their lights and provide products with improved functionality to the industry. This will facilitate industry adoption of project findings.
Animal Health Component
0%
Research Effort Categories
Basic
20%
Applied
50%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2051430102010%
2031430102010%
2042199101010%
6092199301010%
2052199102010%
2032199102010%
2041430101010%
6091430301010%
4021430202010%
4022199202010%
Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 205 - Plant Management Systems; 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 609 - Economic Theory and Methods; 402 - Engineering Systems and Equipment;

Subject Of Investigation
1430 - Greens and leafy vegetables; 2199 - Ornamentals and turf, general/other;

Field Of Science
2020 - Engineering; 1010 - Nutrition and metabolism; 3010 - Economics; 1020 - Physiology;
Goals / Objectives
Controlled environment agriculture (CEA: greenhouses and plant factories) can help meet thechallenge of more intensive, profitable, and sustainable specialty crop production. This projectwill help CEA growers reduce production costs, while giving them more control over cropgrowth and quality. The annual cost of lighting in CEA is high (~$600,000,000/year in the US)It accounts for 40-50% of variable costs in plant factories and 20-30% in greenhouses. Morecost-effective lighting approaches will increase profitability, while reducing energy use andaccompanying greenhouse gas emissions, providing societal and environmental benefits.Manipulating light spectrum and intensity can be used to control crop growth and quality.Ouroverarching goal is to help growers make better lighting decisions and maximize the return oninvestment of their lighting systems. This requires a transdisciplinary approach, integratinghorticulture, economics, engineering, information technology, and social scienceOur specific goals are to develop:1. Lighting strategies to optimize crop growth and quality in cost-effective ways2. Lighting controllers that can automatically implement these strategies3. New sensing technology for monitoring crop growth and physiology4. Software to assess whether use of supplemental lighting is economical5. Software and hardware to implement cost-effective lighting strategies6. Software to simulate different lighting scenarios (Virtual Grower, with USDA-ARS)
Project Methods
Our efforts are divided by subject area, though integration of these different efforts will be paramount.1.Crop production1.1:Crop growth and yieldcan be increased by optimizing 1) light spectrum, 2) light intensity and 3) light capture. This will increase the cost-effectiveness of lighting.The greatest inefficiency in lighting typically occurs when plants are small and much of the light does not fall on the leaves. We will manipulate light intensity and spectrumto promote the rapid development and expansion of leaves, which increases light capture by crop canopies.Light intensity and spectrum interact to determine light absorption and photosynthesis by leaves. Plants use light less efficiently as the intensity increases, but different colors of light interact with intensity to alter this efficiency. We will use state-of-the-art photochemical and physiological measurements to quantify the light use efficiency of selected floriculture and vegetable crops, and develop guidelines to optimize the light spectrum and intensity for growth and yield of a variety of crops.Low-cost controlsystemswill be used to test the effect of improved lighting strategies on crop growth and quality.1.2:Crop quality and valuecan be increased by altering light spectrum, intensity, photoperiod, and timing of light delivery.Plant morphology (height, branching) depends on both the light intensity and spectrum. Management of lighting is thus a powerful tool to control plant shape during development. We will test morphiological response to different lighting methods.Production of desirable secondary compounds, which affect color, flavor, and aroma, depends on both the light intensity and spectrum. Dynamic lighting programs will be developed to maximize yield during active growth, while finishing the plants with a spectrum and/or intensity that increases secondary compounds, increasing crop quality and value.2.Economic assessment2.1:The return on investment of lightingcan be improved using models that consider plant physiological responses, crop value, real-time electricity pricing, and sunlight.We will integrate horticulture, engineering, and energy informatics to create models that account for the growth and value of the crop and adjust dynamically to fluctuations in electricity prices, current weather, and weather forecasts to maximize the value of supplemental lighting.2.2:Carbon footprint, life cycle assessment and economic cost analysiscan be used to quantify the environmental and social impact of greenhouse and plant factory production.Quantitative data on the environmental impact of lighting technologies and production practices in greenhouses and plant factories will be used to develop actionable information to determine the pros and cons of different crop production systems.2.3:Quantitative information on the costs and benefits of lighting will allow growers to make better decisions.We will develop Decision Support Systems to help growers make decisions applicable to their specific conditions. This will be a stepwise process that will answer: 1) is supplemental lighting cost-effective? 2) If so, are HPS or LED lamps more cost-effective? 3) What is the expected return on investment?3.Engineering3.1:Controllers to implement lighting strategieswill facilitate adoption of more cost-effective lighting strategiesWe will develop low-cost, adaptive controllers (hardware) and open-source software to facilitate grower control of their lighting systems. These controllers can be stand-alone or integrated into existing control systems. The goal is to accelerate the profitable adoption of new lighting technologies and approaches.3.2: Develop canopy sensors to track growth and light use efficiencyCanopy growth imaging will be performed using a color camera, like those used in cell phones, with an overhead view of the crop production area. Leaves will be identified by regions that simultaneously have a high green intensity and low red and blue intensity. Images will be processed automatically to separate leaves from the background and determine changes in size and color over time.We will develop an imaging chlorophyll fluorometer for canopy-wide fluorescence measurement to quantify light use efficiency. Our canopy imaging fluorometer will be based on an image sensor chip with good infrared sensitivity. We will induce fluorescence using a blue laser. This laser beam will scan the canopy using a movable mirror, allowing for spatial measurements.4.Impact assessmentImpact monitoring and evaluation will start at thebeginning of the project for program improvement (formative) and accountability (summative)purposes and continue throughout the project to assess the impact on the controlled environment industry. We will collect multiple types of data using a mixed-methods evaluationframework, including CEA producer surveys (in cooperation with the economicssurveys), interviews, observations, and site visits to collaborating greenhouses. Scientists, growers,and advisory panel members will participate in the evaluation process using a participatory actionresearch model to ensure stakeholder engagement and that the project isachieving its stated objectives and contributing toward a trans-disciplinary systems approach toincreasing CEA profitability and production efficiency.

Progress 08/01/22 to 07/31/23

Outputs
Target Audience:Target audiences we have reached include: 1. Controlled environment agriculture industry (greenhouses, plant factories) 2. Commercial lighting companies 3. University and non-university scientists 4. Graduate students Changes/Problems:The past year was particularly challenging as Marc van Iersel was dealing with serious health issues due to cancer. We suffered a terrible loss with his passing in the spring. Following his loss, we submitted a second NCE and a request to add Rhuanito Ferrarezi to the team to take on Marc's role. Also, our Project Manager, Maria Twedt, transitioned into a new role that is not on this project. The project LAMP manager position was posted, and an individual hired as we entered the final year on the project. Fortunately, Maria is available at UGA to assist with the new Project Manager's transition into this position. Our new Project Manager, Jorges Reyes, will be particularly helpful in Outreach as he has a PhD in the plant sciences. What opportunities for training and professional development has the project provided? We had 16 journal articles and conference proceedings published in addition to two webinars. Three students completed their Doctoral degrees, and three students completed their Master's degrees with work related to this project. We have another Ph.D. candidate scheduled to graduate this summer with their LAMP project work completed. We scheduled four trade journal articles to be published in Produce Grower and involved our graduate students in the development of these journal articles. The first one was published this month, June 2023. Last year we had four grower field trips this past year with advisory panel members interacting with our research teams at three of these field trips. Many student attended the 2022 ASHS Conference, giving oral presentations of their work. We had our annual meeting in June 2022 at Utah State University where students gave presentations to the teams on their work as well. How have the results been disseminated to communities of interest?Results continue to be published in peer-reviewed journal articles, at conference proceedings, webinars, in trade journal articles and at scientific meetings such as ASHS. We continue to maintain our webpage as a resource for growers to grab information as needed. This is provided to them through webinars and grower events. What do you plan to do during the next reporting period to accomplish the goals? We recently received approval for a second NCE. We will complete the small amount of research left, including on-farm trials, and finalizing tools and outreach materials development. The team working on LCA will use and modify existing models for greenhouse crop production and include environmental impacts for crop growth, such as lighting, shading, and heating. They will assess the combination of factors resulting in high yields. And they will also measure environmental sustainability of different sets of environmental factors that result in higher yields using Simapro. Additional modeling with LCA will be performed involving the economics team. We will take our LED light spectrum control studies and test the prediction-based method in commercial CEA production with collaborators. To complete Virtual Grower goals, our USDA team will finish work that helps growers account for the effect of supplemental lighting on heating and cooling requirements. This will involve collaboration with LAMP research teams to incorporate research models into Virtual Grower based on our data outputs. These updates will be tested and then incorporated into industry training sessions. The addition of a cost calculator to estimate the payback period will be added to Virtual Grower. Additional tools for calculating the return of investment (ROI). We will work to develop simulations on the demand side and will simulate prices for certain crops and energy. A net present value (NPV) and internal rate of return (IRR) analysis will be performed for various lighting installations over 10 years. Our goal is to determine the greatest profitability and identify areas where slight, realistic changes may cause profit to change noticeably over the length of the planning horizon. We hope to have this completed in this last year but much of this work is dependent on the USDA moving to a web-based application. For on-farm trials, it is imperative that we test our improved lighting approaches in commercial greenhouses and/or vertical farms to see how well these solutions scale and to determine which hurdles we encounter in commercial settings. These on-farm trials would be completed during winter months since little or no supplemental lighting is used in summertime. In addition, we plan to address issues encountered in the first winter in summer 2023, so we can implement those improvements in the winter of 2023-24. Co-PI Velni of Clemson recently set up a subaward to finish work as planned with Marc for the added NCE, if approved. For this last aspect of research, we would address following questions: 1) Examine the effect of when the supplemental lighting begins (this can vary from 2 AM to 8 AM); 2) Examine the impact of different photoperiods on supplemental lighting cost and plant growth; 3) Study the effect of different 24-hr intervals, e.g., going from noon to noon instead of from midnight to midnight; and 4) Examine the impact of integration of solar energy generation and battery storage into greenhouses to help reduce the energy cost of supplemental lighting. For a greenhouse with given parameters, several factors will be considered including, but not limited to, the size of solar cells/generation, size of battery storage, time of the year, accuracy of sunlight prediction. To bring this together, we have a Project Manager and our Outreach Lead, Neil Mattson, complete our outreach efforts. Finalizing our website into something sustainable and robust will be critical for project completion. We will work with GLASE Consortium and Optimia to share information and helping all of us to provide growers with more organized websites. Over the next year we will be actively involved in conferences and symposiums and continue along with setting up webinars. We have a number of graduate students scheduled to present at conferences in August and October of this year, should the NCE be approved. To complete the Outreach team's decision tree, we will finalize video briefs this fall to then post them on social media and to create an FAQ section on the website for the CEA industry. We will complete an additional year of trade journal articles, planning 4-5 more articles, most likely to be published next spring or summer. We will lay out any additional tools through outreach such as posting the code for our low-cost imaging system based on Raspberry Pi. This will be made available online for free. We have planned to prepare video briefs on reliable lighting, lighting warranties, lighting maps, how to calculate ROI for a non-economist, why use supplemental lighting, how to use DLI maps, the pros and cons of different lighting control approaches, and more. With an approved NCE, we would be able to finish some of the most critical aspects of this project, which is the methods of getting outreach information to the growers and other stakeholders in CEA.

Impacts
What was accomplished under these goals? Goal 1. Lighting strategies to optimize crop growth and quality in cost-effective ways From our last report, the plant physiology lab continued work on studies involving light interception, photosynthesis, morphology, phytonutrients, and plant acclimation to CO2 levels. Studies involving far-red light demonstrate increases in crop growth under sole source lighting by affecting both morphology and photosynthesis of plants. Such effects were not observed in greenhouse production, likely because the light spectrum of the sun overwhelms any effects of the supplemental light spectrum. Goal 2. Lighting controllers that can automatically implement these strategies Engineering work to develop lighting controllers and controller algorithms is nearing completion to implement more cost-effective lighting strategies. Completed were small scale tests of this in our greenhouses at UGA. With our controllers we adjust light intensity based on available sunlight, future sunlight, variable electricity prices and plant lighting needs. We initiated work on hardware development with our engineering team to implement cost-effective lighting strategies. Goal 3. New sensing technology for monitoring crop growth and physiology Research on canopy sensing systems to track the growth of CEA crops and to quantify light use efficiency in real time, nondestructively, is largely completed with a refined chlorophyll fluorescence imaging system that has been validated. We have worked on using regular color cameras for crop imaging, tracking growth and pigmentation. Goal 4. Software to assess whether use of supplemental lighting is economical We completed lighting calculators last year and work on Virtual Grower is nearing completion. Goal 5. Software and hardware to implement cost-effective lighting strategies We have completed studies assessing carbon footprint and life cycle assessment of supplemental lighting systems used in CEA. A Life Cycle Assessment (LCA) showed that switching from Light Emitting Diodes (LEDs) to High Pressure Sodium (HPS) has a benefit of lower environmental impact in each phase, lighting production, use, and disposal. However, the effects during the period the lights are used are much greater than those during the production and disposal phases. To assess environmental impacts, we quantified how these impacts differ in various US regions, where power is generated very differently (wind/solar, natural gas, coal, nuclear).? Goal 6. Software to simulate different lighting scenarios (Virtual Grower, with USDA-ARS) We finished work investigating the effects of supplemental LED lighting on heat compared to conventional lighting systems on the thermal balances, heating loads and air circulation patterns within a greenhouse. We found that while supplemental lighting can impact heating load, other variables need to be considered. Determining Daily Light Integral (DLI) was of most importance when selecting lighting. The data from this project is being assessed with USDA-ARS as they work on Virtual Grower heating models. There has been ongoing work with the user interface for online accessibility to Virtual Grower with development in progress in functions related to Heating, Ventilation, and Air Conditioning (HVAC), lighting, building envelope selection and crop selection screens. The legacy information is integrated in this new user interface. Specifically, for LAMP, the expansion of the existing Virtual Grower software to incorporate LEDs in the lighting section has been completed. Updating the HPS section to allow for users to select for either single or double-ended HPS fixtures with electronic or magnetic ballasts has been completed. Goal 7. Economic and Impact assessment Consumer surveys are completed, and we started work on a decision tree for growers to use to economically assess supplemental lighting needs. The project's outreach team has been working together to develop this tool with input from our advisory panel, economist, and data analytics teams. The focus for our growers is to use this tool to assess whether supplemental lighting is economical and to what degree. As part of the decision tree's components, we completed eight of our twenty planned video briefs. These are 3-5-minute videos that answer FAQs for growers. These will be scheduled for social media posting over the next year to support outreach. All our teams are working on these videos, and we have involved graduate students for their professional development. In impact assessment, evaluations of the project and team capturing information related to project activities, collaborations, and publications is ongoing. IEU continued to observe the LAMP team in meetings and perform audience satisfaction surveys following our outreach activities.

Publications

  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Kim C. and van Iersel MW (2023) Image-based phenotyping to estimate anthocyanin concentrations in lettuce. Front. Plant Sci. 14:1155722. doi: 10.3389/fpls.2023.1155722
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Haidekker, M.A.; Dong, K.; Mattos, Erico; van Iersel, M.W. (2022) A very low-cost pulse-amplitude modulated chlorophyll fluorometer. Computers and Electronics in Agriculture. 203: 107438. https://doi.org/10.1016/j.compag.2022.107438
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Liu, Jun, and Marc W. van Iersel. "Anthocyanins Decrease Photosynthesis of Lettuce in a Waveband-dependent Manner." HORTSCIENCE. Vol. 57. No. 9. 113 S WEST ST, STE 200, ALEXANDRIA, VA 22314-2851 USA: AMER SOC HORTICULTURAL SCIENCE, 2022.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Liu, J.; and van Iersel, M.W. (2022) Substituting Red Photons with Far-Red Photons in Indoor Production Did Not Affect Lettuce Yield. In 2022 ASHS Annual Conference. ASHS.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Kim C. and van Iersel M.W. (2022) Low Temperature Induces Rapid Anthocyanin Accumulation in Leafy Vegetables. In 2022 ASHS Annual Conference. ASHS.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: van Iersel, M. (2022) (RE)-Defining Photosynthetically Active Radiation: The Importance of Far-Red. [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Baltimore, MD. https://scisoc.confex.com/scisoc/2022am/meetingapp.cgi/Paper/141457
  • Type: Theses/Dissertations Status: Published Year Published: 2022 Citation: Kim, Changhyeon. (2022) Canopy size and anthocyanin imaging: applications in controlled environment agriculture and phenotyping. Dissertation. University of Georgia. 9949515825002959. 232 p.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Zhen, S., and van Iersel, M.W. (2022) Far-Red, Photosynthesis, and Redefining PAR. In 2022 ASHS Annual Conference. ASHS.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: S. Afzali, Y. Bao, M. W. Van Iersel and J. M. Velni, "Optimal Lighting Control in Greenhouses Using Bayesian Neural Networks for Sunlight Prediction," 2022 European Control Conference (ECC), London, United Kingdom, 2022, pp. 1140-1145, doi: 10.23919/ECC55457.2022.9838124.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Liu, J.; van Iersel, M.W. Far-Red Light Effects on Lettuce Growth and Morphology in Indoor Production Are Cultivar Specific. Plants 2022, 11, 2714. https:// doi.org/10.3390/plants11202714
  • Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Jayalath, Theekshana C. (2023) Manipulating horticultural lighting to optimize crop production in controlled environmental agriculture. Dissertation. University of Georgia. 9949574301502959. 185p.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Liu, Jun and Bugbee, Bruce, "Differences in the Spectral Output of Single- and Double-Ended High-Pressure-Sodium Lamps" (2023). Photobiology. Paper 1. https://digitalcommons.usu.edu/cpl_photobiology/1
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Blonquist, M. Jr., & Bugbee, B. (2022) PAR Data in Field Agriculture: Sensor Accuracy and Stability, Estimates from Solar Measurements, Cloud Enhancements [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Baltimore, MD. https://scisoc.confex.com/scisoc/2022am/meetingapp.cgi/Paper/141448
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Kusuma P and Bugbee B (2023) On the contrasting morphological response to far-red at high and low photon fluxes. Front. Plant Sci. 14:1185622. doi: 10.3389/fpls.2023.1185622
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Zhen, S., Iersel, M. W. v., & Bugbee, B. (2022). Photosynthesis in sun and shade: the surprising importance of far?red photons. New Phytologist, 236(2), 538-546. https://doi.org/10.1111/nph.18375
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Eylands, Nathan (2022) Temporal and Spatial Localization of Cellular Elongation in Lettuce (Lactuca sativa L.) in Response to Far-Red Radiation. In 2022 ASHS Annual Conference. ASHS.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Ashenafi, E.L., Nyman, M.C., Holley, J.M., Mattson, N.S. (2023) The influence of LEDs with different blue peak emission wavelengths on the biomass, morphology, and nutrient content of kale cultivars, Scientia Horticulturae, Volume 317: 111992, ISSN 0304-4238, https://doi.org/10.1016/j.scienta.2023.111992.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Xia, J.; Mattson, N. (2022) Response of Common Ice Plant (Mesembryanthemum crystallinum L.) to Photoperiod/Daily Light Integral in Vertical Hydroponic Production. Horticulturae, 8, 653. https://doi.org/10.3390/horticulturae8070653
  • Type: Theses/Dissertations Status: Published Year Published: 2023 Citation: Eylands, Nathan Jon. 2023. "Anatomical, Physiological, and Photomorphogenic Responses of Lettuce and Basil to Far-Red Radiation Under Sole-Source Lighting." Order No. 30245527, Cornell University. https://www.proquest.com/dissertations-theses/anatomical-physiological-photomorphogenic/docview/2828038785/se-2.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2022 Citation: Percival, AC., and Craver, JK. (2022) The Influence of Temperature and a Low Red to Far-Red Ratio Applied All-Day or at End-of-Day on Growth and Morphology of Petunia � hybrida Seedlings. In 2022 ASHS Annual Conference. ASHS.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Lubna FA, Both AJ. (2022) Assessing the Environmental Impacts of Supplemental Lighting for Crop Production across the United States. In HORTSCIENCE 2022 Sep 1 (Vol. 57, No. 9, pp. S63-S63). Amer Soc Horticultural Science.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Daniel, J., Secor, W., & Campbell, B. (2023). Impact of Information on Attitudes Regarding Greenhouse Lighting Externality Regulation. Journal of Agricultural and Applied Economics, 55(2), 358-375. doi:10.1017/aae.2023.20
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Harbick, K. and Mattson, N.S. (2022). Optimization of spatial lighting uniformity using non-planar arrays and photosynthetic photon flux density modulation. Acta Hortic. 1337, 101-106 DOI: 10.17660/ActaHortic.2022.1337.14
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Mattson, N.S., Allred, J.S., De Villiers, D., Shelford, T., Harbick, K.J. 2022. Response of hydroponic baby leaf greens to LED and HPS supplemental lighting. Acta Horticulturae. 1337:395-402. https://doi.org/10.17660/ActaHortic.2022.1337.54.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Thomas, M.D., Heckathorn, S.A., Boldt, J.K. 2023. Elevated CO2 increases severity of thermal hyponasty in leaves of tomato. Horticulturae. 9:907. https://doi.org/10.3390/ horticulturae9080907.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Atkins, I.K., Boldt, J.K. 2022. Photosynthetic responses of greenhouse ornamentals to interaction of irradiance, carbon dioxide concentration, and temperature. Journal of the American Society for Horticultural Science. 147(2):82-94. https://doi.org/10.21273/JASHS05115-21.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Both, AJ. (2022). Correction to: On-Farm Energy Production: Solar, Wind, Geothermal. In: Ciolkosz, D. (eds) Regional Perspectives on Farm Energy. Springer, Cham. https://doi.org/10.1007/978-3-030-90831-7_16
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Ricks, J., Secor, W., & Campbell, B. L. (2023). Consumer Preference for Microgreens in the Presence of LED Lights and Information Treatments. HortScience, 58(3), 327-332. https://doi.org/10.21273/HORTSCI16948-22


Progress 08/01/21 to 07/31/22

Outputs
Target Audience:1. Controlled environment agriculture industry (greenhouses, plant factories) 2. Commercial lighting companies 3. University and non-university scientists 4. Graduate students Changes/Problems:The past year was challenging due to the ongoing COVID pandemic and subsequent restrictions. Because of COVID we were unable to proceed with in-person activities such as field trips. On-farm trials were again delayed. Our annual meeting was initially scheduled for January 2022, however, another COVID outreach caused us to have to postpone it until May. We added Nathan Janke to the Advisory Panel following Will Healy's retirement from Ball Horticulture. We also added Melanie Yelton to our Advisory Panel from Plenty. What opportunities for training and professional development has the project provided?Our team continue to be exposed to the latest in LED technology with opportunities to study plant responses to different lighting strategies. An example is our work on plant responses to far-red lighting strategies. Undergraduate students continue to gain hands-on research experience in hydroponics and plant responses to lighting research. Graduate students in horticulture, engineering, and data analytics are learning the real-world benefits of collaborative work. An example of that is our engineering team's work with our plant physiology team on plant imaging systems and chlorophyll fluorescence instrumentation. They have a very unique opportunity with this project given its interdisciplinary nature. Many of our graduate students attended the 2021 ASHS Annual Conference last August and presented at other meetings as well. We were able to have an annual LAMP team meeting in-person at Utah State University in May. With 35 people in attendance, we had approximately 20 graduate students (2 of those joined remotely) participating by presenting their research to PIs and Advisory Panel members. They were able to present research projects and collaborate with a diverse team. This annual meeting comes at the end of the year following many routine focus meetings that we had via zoom. PIs continue to push students to focus on industry outcomes, engaging our Advisory Panel for feedback. Graduate students are gaining invaluable team experience on a multi-million-dollar, trans-disciplinary project with very specific targeted goals for industry outcomes. How have the results been disseminated to communities of interest?Results have been published in peer-reviewed journal articles, at conference proceedings, guest lectures and webinars (i.e., Virtual Lighting Short Course), in trade journal articles, and at scientific meetings such as ASHS and grower meetings such as Cultivate. We continue to maintain our webpage regularly (www.hortlamp.org) and utilized sharing information on our webpage through social media platforms such as Facebook, LinkedIN and YouTube. What do you plan to do during the next reporting period to accomplish the goals?We will be focused on on-farm trials over the next reporting period along with finishing up the development of tools and outreach materials. We are working with GLASE and Optimia to share information and make our website more organized. We will initiate additional outreach on the lighting cost calculators. Three video briefs outline how to use each calculator will be posted online. The team working on life cycle analysis (LCA) will use and modify existing models for greenhouse crop production and include environmental impacts for crop growth, such as lighting, shading, and heating. They will assess the combination of factored resulting in high yields. And they will also measure environmental sustainability of different sets of the environmental factors that result in higher yields using Simapro. Additional modeling with LCCA will be performed involving the economics team. We will take our LED light spectrum control studies and test the prediction-based method in commercial CEA production with collaborators. To completed the LAMP goals in Virtual Grower, our USDA team will finish work that helps growers account for the effect of supplemental lighting on heating and cooling requirements. This will involve collaboration with LAMP research teams to incorporate research models into VG based on out data outputs. These updates will be tested and then incorporated into industry training sessions. Overall, our project goals with VG will be implemented once the USDA completes the transition to a web-based interface along with other updates in the system that involve heating and cooling applications. The addition of a cost calculator to estimate payback period will be added to VG. Additional tools for ROI. We will work to develop simulations on the demand side and will simulate prices for certain crops and energy. A net present value (NPV) and internal rate of return (IRR) analysis will be performed for various lighting installations over 10 years. Our goal is to determine the greatest profitability and identify areas where slight, realistic changes may cause profit to change noticeably over the length of the planning horizon. The impact evaluation team will continue to survey our team through member surveys, and assessment of team meetings and outreach events. Information will continue to be delivered to the PD for continuous improvement. Communications within our organizations will be used to provide press releases for different aspects of the project. We will continue to maintain our webpage and will actively pursue the use of the LinkedIN page. We will continue to connect to individuals in the CEA industry at conferences such as Cultivate. We will continue to submit articles for trade journals. Webinars, webpage updates/posting and engaging in social medial will continue to increase. Short videos briefs are being scheduled to begin posting to our webpage and our social media platforms. These videos will cover FAQs that growers might have relating to CEA lighting.

Impacts
What was accomplished under these goals? Goal 1. Lighting strategies to optimize crop growth and quality in cost-effectiveways In plant physiology, our studies involving light interception, photosynthesis, and morphology are largely completed. We continue to work on phytonutrients and plant acclimation to elevated CO2 levels. We have shown that far-red light can increase crop growth under sole source lighting by affecting bot morphology and photosynthesis of plants. Such effects were not observed in greenhouse production, likely because the light spectrum of the sun overwhelms any effects of the supplemental light spectrum. Goal 2. Lighting controllers that can automatically implement these strategies Much work has been done with UGA engineering to develop controllers and controller algorithms to implement more cost-effective lighting strategies. We have completed tests of this on a small scale in our greenhouses at UGA. With our controllers we adjust light intensity based on available sunlight, future sunlight, variable electricity prices and plant lighting needs. Hardware is being developed with our engineering team to implement cost effective lighting strategies. Goal 3. New sensing technology for monitoring crop growth and physiology Research on canopy sensing systems to track the growth of CEA crops and to quantify light use efficiency in real time, nondestructively, is largely completed. The chlorophyll flourscense imaging system has been validated and refined. We have also started working on using regular colr cameras for crop imaging, to track both growth and pigmentation. Our multispectral imaging system is a simple and low-cost to based on Rasberry Pi. The code will be made freely available online. Goal 4. Software to assess whether use of supplemental lighting is economical We now have 3 completed LAMP Lighting Cost Calculators available online on the LAMP Outreach page. The first calculator determines how much electricity is required to reach the target DLI every single day of the year. Since this is based on an unrealistic scenario of setting up a lighting system designed to provide enough light on even the darkest day of the year, the other two calculators were developed. The second calculator allows users to specify how many days of the year they want to be able to reach their target DLI to determine the required lighting capacity for their greenhouse. The third calculator takes the opposite approach of the 'unlimited lighting calculator'. Users specify the capacity of their lighting system and the calculator estimates how many days of the year they can reach their target DLI. Goal 5. Software and hardware to implement cost-effective lighting strategies We have completed our studies assessing carbon footprint and life cycle assessment of supplemental lighting systems used in CEA. LCA showed that switching from LEDs from HPS has a benefit of lower environmental impact in each phase, lighting production, use, and disposal. However, the effects during the period the lights are used are much greater than those during the production and disposal phases. To assess environmental impacts, we also quantified how these impacts differ in various US regions, where power is generated very differently (wind/solar, natural gas, coal, nuclear). Goal 6. Software to simulate different lighting scenarios (Virtual Grower with USDA-ARS We finished work investigating the effects of supplemental LED lighting on heat compared to conventional lighting systems on the thermal balances, heating loads and air circulation patterns within a greenhouse. We found that while supplemental lighting can impact heating load, other variables need to be considered. Determining DLI was of most importance when selecting lighting. The data from this project will be assessed with USDA-ARS as they work on VG heating models. The new user interface for online accessibility to Virtual Grower is in development with HVAC, lighting, building envelope selection and crop selection screen created. The legacy information is integrated in this new user interface. Specifically, for LAMP, the expansion of the existing VG software to incorporate LEDs in the lighting section has been completed. Updating the HPS section to allow for users to select for either single or double-ended HPS fixtures with electronic or magnetic ballasts has been completed. Goal 7. Economic and Impact assessment Consumer surveys have been completed. We have initiated work on a decision tree for growers to use to economically assess supplemental lighting needs. The development of this tool will include our outreach team, our advisory panel, economist and data analytics teams. The focus for our growers for this tool will be to assess whether supplemental lighting is economical and to what degree. In impact assessment, evaluations of the project and team capturing information related to project activities, collaborations, and publications is ongoing. IEU continues to observe the LAMP team in meetings and perform audience satisfaction surveys following our outreach activities.

Publications

  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Boldt, J. K., & J.E. Altland. 2021. Comparison of supplemental lighting from high-pressure sodium lamps or light-emitting diodes on morphology and nutrient uptake of greenhouse crops. In IX International Symposium on Light in Horticulture 1337, pp. 313-322. https://doi.org/10.17660/ActaHortic.2022.1337.42
  • Type: Book Chapters Status: Published Year Published: 2022 Citation: Both, A. J. 2022. Greenhouse Energy Efficiency and Management. In Regional Perspectives on Farm Energy pp. 85-93. Springer, Cham. https://link.springer.com/chapter/10.1007/978-3-030-90831-7_11
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Lubna, F.A., D.C. Lewus, T.J. Shelford, and A.J. Both. 2022. What you may not realize about vertical farming. Horticulturae 8, 322. https://doi.org/10.3390/horticulturae8040322
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Shelford, T., A.J. Both, and N. Mattson. 2022. A greenhouse daily light integral control algorithm that takes advantage of day ahead market electricity pricing. Acta Horticulturae 1337:277-282. https://doi.org/10.17660/ActaHortic.2022.1337.34
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Lubna, F. A., U. Krogmann, & A.J. Both, 2021. Assessing Environmental Impacts of HPS and LED Plant Lighting Systems operated in Three Different Interconnected US Electricity Grids. In HORTSCIENCE 56( 9), pp. S254-S255.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Both, A. J. 2022. Greenhouse Energy Efficiency and Management. In Regional Perspectives on Farm Energy pp. 85-93. Springer, Cham. https://link.springer.com/chapter/10.1007/978-3-030-90831-7_11 Lubna, F.A., D.C. Lewus, T.J. Shelford, and A.J. Both. 2022. What you may not realize about vertical farming. Horticulturae 8, 322. Shelford, T., A.J. Both, and N. Mattson. 2022. A greenhouse daily light integral control algorithm that takes advantage of day ahead market electricity pricing. Acta Horticulturae 1337:277-282. Llewellyn, D., T.J. Shelford, Y. Zheng, and A.J. Both. 2022. Measuring and reporting lighting characteristics important for controlled environment plant production. Acta Horticulturae 1337:255-264. Lubna, F. A., U. Krogmann, & A.J. Both, 2021. Assessing Environmental Impacts of HPS and LED Plant Lighting Systems operated in Three Different Interconnected US Electricity Grids. In HORTSCIENCE 56( 9), pp. S254-S255. Shelford, T.J. and A.J. Both. 2021. On the technical performance characteristics of horticultural lamps. AgriEngineering 3:716-727. https://doi.org/10.3390/agriengineering3040046
  • Type: Theses/Dissertations Status: Published Year Published: 2022 Citation: Percival, A.C. 2022. Using Far-Red Light to Promote Leaf Expansion for Young Plants. MS Thesis. Department of Horticulture and Landscape Architecture. Colorado State University. https://mountainscholar.org/bitstream/handle/10217/235212/Percival_colostate_0053N_17148.pdf?sequence=1
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Poster session. Percival, A, J. Craver. End-of-Day (EOD) Far-Red Lighting with a Low Daily Light Integral (DLI) Does Not Promote Early Leaf Expansion for Petunia Xhybrida Seedlings.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Croy, D., M.W. van Iersel, M. Twedt, R. Watson, M.C. Boudreau. 2021. Estimating the Electricity Use and Cost of Supplemental Greenhouse Lighting Using an on-Line App.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Croy, D., M.W. van Iersel, M Twedt, R. Watson, M.C. Boudreau. 2021. Estimating the Electricity Use and Cost of Supplemental Greenhouse Lighting Using an on-Line App.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Kim, C., & M.W. van Iersel. Lettuce Dry Matter Partitioning and Canopy Development of Five Different Cultivars over a Growing Cycle.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Liu, J., & M.W. van Iersel. Chlorophyll Fluorescence Imaging to Monitor High Light Stress in Leafy Greens. University of Georgia.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Assessing Environmental Impacts of HPS and LED Plant Lighting Systems operated in Three Different Interconnected US Electricity Grids. Farzana Afrose Lubna, Uta Krogmann and Arend-Jan Both, Rutgers - The State University of New Jersey.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Violet Photons Induce Photoinhibition in Lettuce Rex but Improve Growth of Cucumber Shuyang Zhen, Texas A&M, Paul Kusuma, Utah State University - Crop Physiology Lab and Bruce Bugbee, Utah State University.
  • Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Afzali, S., & J.M. Velni. 2021. Development And Implementation of Optimal Supplemental Lighting Control Strategies In Greenhouses. MS Thesis. University of Georgia.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral presentations. Jayalath, T.C., & M.W. van Iersel. 2021. Reducing Energy Requirements for Greenhouses Lighting through Carry-over of Excess Light to the Next Day.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral Presenations. Kim, C., & M.W. van Iersel. 2021. Lettuce Dry Matter Partitioning and Canopy Development of Five Different Cultivars over a Growing Cycle.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Kim, C., & M.W. van Iersel. 2022. Morphological and Physiological Screening to Predict Lettuce Biomass Production in Controlled Environment Agriculture. Remote Sens. 14, 316. https://doi.org/10.3390/rs14020316
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Kim, C., K. Wacker, B. Sidore, T. Pham, M. Haidekker, & M.W. van Iersel. 2022. Development of an automated pigmentation phenotyping and low- cost multispectral imaging system. J. Earth and Space Science Open Archive. https://outlookuga-my.sharepoint.com/personal/mkuhn_uga_edu/Documents/REEports/YR4/10.1002/essoar.10508805.2
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: 2021 ASHS Conference. Oral Presentations. Mayorga-Gomez, A.M., & M.W. van Iersel. 2021. Lowering the Target DLI Following Sunny Days Can Reduce Lighting Costs in Greenhouse Lettuce Production.
  • Type: Conference Papers and Presentations Status: Submitted Year Published: 2022 Citation: Afzali, S., Y. Bao, M.W. Iersel, J.M. Velni. 2022. Optimal Lighting Control in Greenhouses Using Bayesian Neural Networks for Sunlight Prediction. arXiv preprint arXiv:2205.03733. Accepted for presentation and publication in the proceedings of the 2022 European Control Conference (ECC), July 12-15, 2022.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Afzali S, S. Mosharafian, M.W. van Iersel, J.M. Velni. 2021. Development and Implementation of an IoT-Enabled Optimal and Predictive Lighting Control Strategy in Greenhouses. Plants. 2021; 10(12):2652. https://doi.org/10.3390/plants10122652
  • Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Afzali, S., S. Mosharafian, M.W. van Iersel, J.M. Velni. 2021. Optimal Lighting Control in Greenhouses Equipped with High-intensity Discharge Lamps Using Reinforcement Learning. American Control Conference (ACC), 1414-1419.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Mosharafian, S., S. Afzali, G.M. Weaver, M.W. van Iersel, J.M. Velni. 2021. Optimal Lighting Control in Greenhouse by Incorporating Sunlight Prediction. Computers and Electronics in Agriculture 188, 106300. https://doi.org/10.1016/j.compag.2021.106300
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Mosharafian, S., S. Afzali, J. Mohammadpour Velni, & M.W. van Iersel. 2020. Development and Implementation of a New Optimal Supplemental Lighting Control Strategy in Greenhouses. Proceedings of the ASME 2020 Dynamic Systems and Control Conference. Volume 1. Virtual, Online. October 57, 2020. V001T13A001. ASME.


Progress 08/01/20 to 07/31/21

Outputs
Target Audience:Target audiences we have reached include: 1. Controlled environment agriculture industry (greenhouses, plant factories) 2. Commercial lighting companies 3. University and non-university scientists 4. Graduate students Changes/Problems:The past year was challenging due to the COVID outbreak and subsequent restrictions. Because of COVID we were unable to proceed with in-person activities such as field trips. On-farm trials for the most part have been delayed. We were unable to have our in-person LAMP Annual Meeting. We utilized zoom extensively to meet throughout YR3 of the project. Cultivate '21 was the meeting during YR3 that we were able to attend in-person. We suffered a terrible loss recently with the passing of Ed Harwood, a valued and active LAMP Advisory Panel Member. Two new advisory panel members were selected this summer. Roger Beulow with AeroFarms is replacing Ed. Michael Martin with AmericanHort replaces Jill Calabro. Jill left the Advisory Panel in the spring of 2020 due to a job change. What opportunities for training and professional development has the project provided?Our graduate students at UGA, CSU, Cornell and USU, plus 1 horticulture technician continue to be exposed to the latest in LED technology with opportunities to study plant responses to different lighting strategies. Our horticulture GRAs continue work on plant responses to far-red lighting strategies. Two undergraduate students gained hands-on research experience in hydroponics and plant responses to lighting research Undergraduate students involved gain hands-on research experience. Graduate students participated in Our Mechanical Engineering GRA received his MS finishing up his work on CFD modeling. Two GRAs in Electrical Engineering continued to be supported by the project working on plant imaging systems and chlorophyll fluorescence instrumentation. The unique opportunity for these students is the interdisciplinary nature of the research project. As engineering students, they are exposed to plant physiology and horticulture. Many of our graduate students attended the 2020 ASHS Annual Conference (virtually). One student was involved in the poster session and a number of horticulture students providing oral presentations for their work. We also had several graduate students submit for the 2021 DOE Lighting R&D Workshop Student Poster Competition. Two of our GRAs received awards. Grand prize went to Ruqayah Bhuiyan (UGA), Lettuce tolerates fluctuating light, potentially reducing energy costs in controlled environment agriculture. Honorable Mention went to Nate Eylands (Cornell), Influence of Far-Red Intensity During the Seedling Stage on Photomorphogenic Characteristics in Leafy Greens. We were unable to have our annual meeting this past year because of COVID. However, in the spring we initiated topic-specific meetings so we could have focus sessions and discussion on plant physiology, canopy imaging, engineering applications and economics. In each meeting, both CoPIs and graduate students present their work. We end each presentation with group discussions with a focus on engagement with advisory panel members to gain industry insight to assess practical applications of that work. In this manner, we have worked to keep our students connected with our industry representatives. We were unable to engage in field trips or on-farm trials, however, 2 GRAs at Cornell were able to make a visit and plan and discuss work with Pleasant View Farms. Utah State continued to correspond with Pineae Greenhouses. However, in-person work was not extensive because of COVID related restrictions during YR3. Graduate students are gaining invaluable team experience on a multi-million-dollar, trans-disciplinary project with very specific targeted goals for industry outcomes. How have the results been disseminated to communities of interest?Results have been published in peer-reviewed journal articles, at conference proceedings, guest lectures and webinars, in trade journal articles and at scientific meetings such as ASHS and grower meetings such as Cultivate. Conferences and professional meetings in YR3 of the project were limited due to COVID but we were able to take advantage and participate virtually when travel restrictions were in place. This summer (2021), project members were able to travel to Cultivate to present for Project LAMP. We continue to maintain our webpage regularly (www.hortlamp.org). We have boosted our weekly output to our social media platforms, Facebook, LinkedIN and continue to post videos to our YouTube page. What do you plan to do during the next reporting period to accomplish the goals?In plant physiology, we will continue studies on light intensity and light use efficiency, carrying over 'excess light' to next day studies, far-red and canopy photosynthesis, violet light, quality, pigmentation, and vegetative propagation. Work will continue work on timing, duration, and intensity from initial end of day studies involving far-red in ornamental production. We will continue to assess metrics for reporting light. We will combine short-term physiological measurements with longer-term growth trials. More work will be performed looking at plant acclimation associated with elevated CO2 levels. We will move several plant physiology studies from growth chambers to greenhouse and on-farm trials. We continue to work on additional functionality to the online LAMP Lighting Cost Calculator. We will incorporate time series solar generation data as an input and will build in models of energy consumption. We will work to scale up or otherwise improve lighting control in commercial operations and to further develop imaging technologies in commercial operations. The team working on life cycle analysis (LCA) will focus on regional locations and pull together data to determine more detailed economic impact of lighting choices such as the cost difference between LED and HPS fixtures. We will expand and incorporate LCCA into some of our calculator tools. More sophisticated modeling with LCCA will be performed involving the economics team. We will take our LED light spectrum control studies and test the prediction-based method in commercial CEA production with collaborators. For Virtual Grower, we initiate work on the LED lighting and energy modeling functionality. This will involve collaboration with LAMP research teams to incorporate research models into VG based on out data outputs. These updates will be tested and then incorporated into industry training sessions. We will work to develop simulations on the demand side and will simulate prices for certain crops and energy. A net present value (NPV) and internal rate of return (IRR) analysis will be performed for various lighting installations over 10 years. Our goal is to determine the greatest profitability and identify areas where slight, realistic changes may cause profit to change noticeably over the length of the planning horizon. The impact evaluation team will continue to survey our team through member surveys, and assessment of team meetings and outreach events. Information will continue to be delivered to the PD for continuous improvement. We will continue to work with growers, our outreach program, research teams and our advisory panel as we improve and continue development to decision tools to assist with production. Communications within our organizations will be used to provide press releases for different aspects of the project. We will continue to maintain our webpage and will actively pursue the use of the LinkedIN page. We will continue to connect to individuals in the CEA industry at conferences such as Cultivate. We will continue to submit articles for trade journals. Webinars, webpage updates/posting and engaging in social medial will continue to increase. Short videos will be posted to social media with a "what we've learned" focus from our students. In partnership with GLASE and OptimIA (an SCRI project) we have initiated a Virtual Lighting Short Course. This course will begin in October and ends just before Thanksgiving. This 6-module online course will be completed in November. This is an example of the training that we'll be providing to the industry on topics such as lighting fixture set up, use of decision-support tools, etc.

Impacts
What was accomplished under these goals? Goal 1. Lighting strategies to optimize crop growth and quality in cost-effectiveways In plant physiology, we studied different light intensities and light use efficiency, carrying over 'excess light' to next day studies, far-red and canopy photosynthesis, violet light, quality, pigmentation and vegetative propagation. We continued conducting trials in growth chambers, growing plants under white light, with blue, red and far-red provided at the end of the photoperiod. We investigated timing, duration and intensity from initial end of day studies involving far-red in ornamental production. We continued to assess metrics for reporting light. We combined short-term physiological measurements with longer-term growth trials. With input from Pleasant View Farms, developed concepts for determining what is an appropriate DLI sum of enhanced liners to finish in 4 weeks. We continued to look at plant acclimation associated with elevated CO2 levels. Goal 2. Lighting controllers that can automatically implement these strategies Our engineering team has developed a prediction-based method which adjusts light intensity based on sunlight and electricity price. Work last year resulted in a model predicting sunlight using historical data using a Markov model. This sunlight prediction is then used to find the optimal lighting strategy. The algorithms employed in a testbed environment using Raspberry Pi were implemented in a greenhouse to test plant responses. Measured growth parameters demonstrated that sufficient plant growth was maintained, and the proposed strategy demonstrated a significant reduction in costs. Goal 3. New sensing technology for monitoring crop growth and physiology We planned to expand the use of our canopy imaging system to other project facilities for studies at Cornell and CSU. This simple, effective, and relatively low-cost method takes images without damaging crops. We continue to refine our system with improvements. We can now synchronize blue measurement LED with camera exposure interval. Our teams are working together to improve image distortion issues with different lenses by means of a step-by-step protocol designed to troubleshoot this issue. With our imaging system that uses chlorophyll fluorescence to measure the photosynthetic activity of plants, we were able to prove and validate its use. The next phase involves further refinement to the system. The fiber optic fluorometer appears to be the more practical system with ease of optical alignment inside the instrument. We've reduced the overall cost per-unit to under $250 and had significant hardware and software revisions based on experience with initial experiments. Goal 4. Software to assess whether use of supplemental lighting is economical We finished modifications and beta tested our web-based lighting cost calculator. On our "Determining Supplemental Lighting" page (https://www.hortlamp.org/outreach/determine-lighting/) you can find the LAMP Lighting Cost Calculator plus that same calculator is available in spreadsheet format. Additionally, we have links to interactive DLI maps and another spreadsheet that helps growers determine how many light fixtures they need. With the LAMP Lighting Cost Calculator, growers input their location, parameters for greenhouse design (size, transmission %, target DLI, and lighting efficacy) and are given lighting costs. Reports for the lighting costs are accomplished with an online generated visual or with a downloadable PDF file or spreadsheet. We will continue to develop additional iterations of the lighting cost calculator to deploy in this web-based format. (see section on plans for next reporting period). Goal 5. Software and hardware to implement cost-effective lighting strategies A GRA in engineering work on life cycle assessment (LCA) of supplemental lighting systems used in CEA. Previous assessments were performed with a global outlook. We narrowed these assessments down to the US with a focus on three different product phases for LEDs (production, uses and disposal). The 'uses' phase dominates environmental impact for this product. To look at sustainability options, we looked at 3 main electricity grids in the US. We found that the nuclear sources for the energy grids were more sustainable. When LED lamps are placed within a canopy and emit light sideways, horizontal 180° will not correctly measure the entire PAR output. We are investigating whether 360° light measurements have advantages when measuring PAR. Initial studies involved deploying sensor array in a greenhouse with a tall crop and collected measurements over extended periods of time. These studies are ongoing. Goal 6. Software to simulate different lighting scenarios (Virtual Grower, with USDA-ARS) An engineering MS GRA completed a project investigating the effects of supplemental LED lighting on heat compared to conventional lighting systems on the thermal balances, heating loads and air circulation patterns within a greenhouse. His work found that while supplemental lighting can impact heating load, other variables need to be considered. Determining DLI was of most importance when selecting lighting. The data from this project will be assessed with USDA-ARS as they work on VG heating models. USDA-ARS hired an IT specialist during year 3, who has begun initiating program changes for Virtual Grower for this project. Work this past year has involved assessing platforms for developing a cloud-based systems so that end users can access VG from any location. Their next step has been to replicate the functionality of VG and put it on the cloud-based platform. Goal 7. Economic and Impact assessment Our Economic team performed a survey of US consumers, randomly picked through our database. There were questions about demographics, price, quality. We considered consumer locations to greenhouses and if there were issues with the industry (ex. Lighting pollution). Two graduate students are assessing for adverse social components so we can look for options to manage/fix these aversions. The IEU GRA performed ongoing evaluations of the project and team capturing information related to project activities, collaborations, and publications. The IEU team published a journal article based on evaluating our social network. They continue to observe the LAMP team in virtual meetings and perform audience satisfaction surveys following our outreach activities. This year, IEU developed and implemented our Buddy System Program (BSP). Through the BSP, we connect a graduate student with an advisory panel member to give our students a unique exposure to our industry for additional professional development. We intended this program to have more in-person exposure to the industry, but this was severely limited due to COVID travel restriction. IEU will monitor the BSP for impact to help determine its usefulness.

Publications

  • Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Bhuiyan, R. 2021. Lighting approaches to improve growth in controlled environment systems. MS thesis, University of Georgia, Athens, GA.
  • Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Kasuma, P. 2021. Phytochrome physiology and plant perception of far-red photons. PhD Dissertation, Utah State University, Logan, UT.
  • Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Ilardi, M. 2021. Supplemental lighting time best justifies the efficacy of transition from HPS lighting to LED lighting in Greenhouse. MS Thesis, University of Georgia, Athens, GA.
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Legendre, R. 2020. Applications of digital imaging in plant phenotyping: morphology, physiology, and genotyping. PhD dissertation, University of Georgia, Athens, GA.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Bhuiyan, R., & M.W. van Iersel. 2021. Only Extreme Fluctuations in Light Levels Reduce Lettuce Growth Under Sole Source Lighting. Front. Plant Sci. 12:619973. doi.org/10.3389/fpls.2021.619973
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Elkins, C., & M.W. van Iersel. 2020. Longer Photoperiods with the Same Daily Light Integral Improve Growth of Rudbekia Seedlings in a Greenhouse. HortScience, 55(10), 16761682. doi.org/10.21273/HORTSCI15200-20
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Elkins, C., & M.W. van Iersel. 2020. Longer Photoperiods with the Same Daily Light Integral Increase Daily Electron Transport through Photosystem II in Lettuce. Plants, 9(9), 1171. doi.org/10.3390/plants9091172
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Elkins, C., & M.W. van Iersel. 2020. Supplemental Far-red Light-emitting Diode Light Increases Growth of Foxglove Seedlings under Sole-source Lighting. HortTechnology, 50(5), 564569. doi.org/10.21273/HORTTECH04661-20
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Liu, Jun, M.W. van Iersel. 2021. Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms. Front. Plant Sci. 12:619987. doi.org/10.3389/fpls.2021.619987
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Palmer, S., & M.W. van Iersel. 2020. Increasing Growth of Lettuce and Mizuna under Sole-source LED Lighting Using Longer Photoperiods with the Same Daily Light Integral. Agronomy, 10(11), 1659. doi.org/10.3390/agronomy10111659
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Zhen, S., & B. Bugbee. 2020. Substituting Far-red for Traditionally Defined Photosynthetic Photons Results in Equal Canopy Quantum Yield for CO2 Fixation and Increased Photon Capture during Long-term Studies: Implications for Re-defining PAR. Frontiers in Plant Science, 11, 581156. doi.org/10.3389/fpls.2020.581156
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Zhen, S., M. van Iersel, B. Bugbee. 2021. Why Far-Red Photons Should Be Included in the Definition of Photosynthetic Photons and the Measurement of Horticultural Fixture Efficacy. Frontiers in Plant Science, 12, 1158. doi.org/10.3389/fpls.2021.693445
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Steady-state Stomatal Responses of C3 and C4 Species to Blue Light Fraction: Interactions with CO2 Concentration. Plant, Cell, and Environment. doi.org/10.3389/fpls.2021.693445
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: van Iersel, M., A. Mayorga-Gomez, T. Jayalath. How To Convert Sunny Days to Energy Savings in the Greenhouse. Greenhouse Grower. July 2021. www.greenhousegrower.com/technology/how-to-convert-sunny-days-to-energy-savings-in-the-greenhouse/
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Mayorga-Gomez, A., & M. van Iersel. Not All DLIs Are the Same. Greenhouse Production News. June 2021. https://gpnmag.com/article/not-all-dlis-are-the-same/
  • Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Cultivate 21 Presentation. Marc van Iersel and Bruce Bugbee, New Lighting Strategies in Greenhouse and Indoor Crop Production. July 11, 2021.
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Jayalath, T.C, & M.W. van Iersel. 2021. Canopy Size and Light Use Efficiency Explain Growth Differences between Lettuce and Mizuna in Vertical Farms. Plants, 10(4), 704. doi.org/10.3390/plants10040704
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Kusuma, P., P.M. Pattison, & B. Bugbee. 2020. From Physics to Fixtures to Food: Current and Potential LED Efficacy. Horticulture Research 7:56. doi.org/10.1038/s41438-020-0283-7
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Kusuma, P., B. Swan, & B. Bugbee. 2021. Does Green Really Mean Go? Increasing the Fraction of Green Photons Promotes Growth of Tomato but Not Lettuce or Cucumber. Plants, 10(4), 637. doi.org/10.3390/plants10040637
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Kusuma, P., & B. Bugbee. 2021. Improving the Predictive Value of Phytochrome Photoequilibrium: Consideration of Spectral Distortion Within a Leaf. Front. Plant Sci. 12:596943. doi.org/10.3389/fpls.2021.596943
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Kusuma, P., & B. Bugbee. 2020. Far-red Fraction: An Improved Metric for Characterizing Phytochrome Effects on Morphology. J. Amer. Soc. Hort. Sci. 146(1), 3-13. doi.org/10.21273/JASHS05002-20
  • Type: Journal Articles Status: Published Year Published: 2021 Citation: Legendre, R., M.W. van Iersel. 2021. Supplemental Far-red Light Stimulates Lettuce Growth: Disentangling Morphological and Physiological Effects. Plants, 10(1), 166. doi.org/10.3390/plants10010166
  • Type: Conference Papers and Presentations Status: Other Year Published: 2021 Citation: Cultivate 21 Presentation. Jennifer Boldt and Josh Craver. Lighting and CO2 Management and Optimization. July 11, 2021.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: 2020 Annual AHSH Conference. Poster Session. Comparing HPS and LED Plant Lighting Systems Using Life Cycle Assessment Approach, Farzana Afrose Lubna and Arend-Jan Both, Rutgers-The State University of New Jersey. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33261
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. Only Extreme Fluctuations in Lights Levels Reduce Lettuce Growth, Ruqayah Bhuiyan and Marc W. van Iersel, University of Georgia. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33113
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. The Quantum Requirement for CO2 Assimilation Increases with Increasing Photosynthetic Photon Flux Density and Leaf Anthocyanin Concentration in Lettuce, Changhyeon Kim and Marc W. van Iersel, University of Georgia. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33091
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. Supplemental Far-Red Light Does Not Increase Growth of Greenhouse-Grown Lettuce, Theekshana C Jayalath and Marc W. van Iersel, University of Georgia. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33260
  • Type: Websites Status: Published Year Published: 2021 Citation: https://www.hortlamp.org. Significant changes and updates have been published to the Project LAMP Webpage during Year 3 of the project. Including establishing quick links to the LAMP Lighting Cost Calculator.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. Light Intensity Changes Leaf-Level and Crop-Level Water Use Efficiency, Laura E Reese and Marc W. van Iersel, University of Georgia. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33161
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. Influence of Far-Red Intensity during the Seedling Stage on Photomorphogenic Characteristics in Leafy Greens, Nathan J. Eylands and Neil Scott Mattson, Cornell University. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/32957
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: 2020 Annual AHSH Conference. Oral Presentations. Supplemental Far-Red Light Increases Final Yield of Indoor Lettuce Production By Boosting Light Interception at the Seedling Stage, Jun Liu and Marc W. van Iersel, University of Georgia. https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33085


Progress 08/01/19 to 07/31/20

Outputs
Target Audience:Target audiences we have reached include: 1. Controlled environment agriculture industry (greenhouses, plant factories) 2. Commercial lighting companies 3. University and non-university scientists 4. Graduate students Changes/Problems:With Dr. Tessa Pocock's resignation from Rensselaer Polytechnic Institute (RPI), we completed the reallocation of those funds with the addition of Dr. Joshua Craver from Colorado State University. Additionally, Kale Harbick resigned from Cornell University and took a position with the USDA-ARS Greenhouse Production Research Group (GPRG). We are fortunate to be able to continue work with Kale on project LAMP in his new role. As such, we are working with ARS to have Kale established as coPI on the project in his new role with GPRG. The Virtual Grower (VG) part in LAMP had been delayed due to a vacancy in the ARS GPRG IT programmer position. But with the recent hire of Kale this past January and the IT support position currently posted, this aspect of the project should be initiated this year. The biggest setback was the unexpected passing away of Dr. Paul Thomas in Fall 2019. Paul not only was a valued colleague, but also a key member of our outreach team. Other team members will be taking on additional outreach responsibilities. What opportunities for training and professional development has the project provided?At UGA, 14 graduate students, 1 post-doc, 3 undergraduates, and 1 horticulture technician participated in this project, were exposed to the latest in LED technology, and had the opportunity to study plant responses to different lighting strategies. The undergraduates gained hands-on research experience. Six undergraduates (two teams of three students) in statistics performed their capstone projects on using imaging techniques to quantify chlorophyll and anthocyanins. They gained experience in handling large data sets and running simulations. One GRA continued work in research evaluation and attended the annual American Evaluation Association conference in November. One GRA in Mechanical Engineering, continued work on CFD modeling. Two GRAs in Electrical Engineering continued to be supported by the project working on plant imaging systems and chlorophyll fluorescence instrumentation. The unique opportunity for these students is the interdisciplinary nature of the research project. As engineering students, they are exposed to plant physiology and horticulture. A GRA in computer engineering worked on coding in Python to develop a web-based plant growth simulator. At Cornell University, a PhD student and 2 undergraduates have continued to work on the project. The GRA continued work on plant responses to far-red lighting strategies. Two undergraduate students gained hands-on research experience in hydroponics and plant lighting research (Fall semester 2019 and Spring semester 2020). At Utah State University, 2 GRAs and undergraduate students continued work investigating plant responses to lighting with the latest technology. We had our second annual meeting this spring over 2.5 days, hosted by Cornell. CoPIs and graduate students were able to present on work accomplished over the last year and discuss goals for the upcoming year. We had everyone outline needs or support they could use from the group and specific areas of interest where they want to find collaboration. The annual meeting involves coPDs, coPIs, graduate students, post-docs, and advisory panel members. This same group meets quarterly for a few hours. At each of these meetings, we get feedback from the advisory panel on the project for continuous improvement. For all of our meetings, we use Zoom to videoconference so everyone can participate regardless of their location throughout the US or ability to travel. These meetings are recorded and posted to our Open Science Framework project page so that anyone unable to meet can get connected to our progress at a later time. For the larger group located at the University of Georgia, we host monthly in-person meetings to facilitate communication and collaboration with this larger group on the project. All of our meetings allow our project participants to share scholarly information, thereby providing professional development for research teams, outreach, and our industry partners. We have had a number of field trips with project teams to greenhouses. UGA visited James Greenhouses and observed a small lighting setup and on-farm trial at that location. Cornell visited Peace Tree Farms to discuss a study involving basil and upcoming trials and CO2. Utah State has interacted with Pineae Greenhouses who has installed a few acres of LED lights within the last year. USU provided guidance on LED installations and production results and assisted with energy rebate information for electricity. Graduate students are gaining invaluable team experience on a multi-million-dollar, trans-disciplinary project with very specific targeted goals for industry outcomes. How have the results been disseminated to communities of interest?Results have been published in peer-reviewed journal articles, at conference proceedings, guest lectures and webinars, and have been presented at scientific meetings [USDA regional project NCERA-101 Controlled Environment Technology and Use; American Society for Horticultural Science (webinar and conference proceedings)] and grower meetings (Cultivate). We maintained our webpage and continue to add to it regularly as progress is made (www.hortlamp.org). We have initiated a LinkedIN and YouTube page to provide additional outreach tools to the CEA industry. What do you plan to do during the next reporting period to accomplish the goals?In plant physiology, we will study different light intensities and light use efficiency, carrying over 'excess light' to next day studies, far-red and canopy photosynthesis, violet light, quality, pigmentation and vegetative propagation. We will finish conducting trials in growth chambers, growing plants under white light, with blue, red and far-red provided at the end of the photoperiod. Future research will determine timing, duration and intensity from initial end of day studies involving far-red in ornamental production. We will continue to assess metrics for reporting light. We will combine short-term physiological measurements with longer-term growth trials. With input from Pleasant View Farms, we are developing concepts for determining what is an appropriate DLI sum of enhanced liners to finish in 4 weeks. We will continue to look at plant acclimation associated with elevated CO2 levels. We will move a number of our plant physiology studies from growth chambers to greenhouse and on-farm trials. We will continue to refine our lighting calculators. The following inputs are being considered, photoperiod, light fixture output (umol/s) and price per fixture. These inputs would provide outputs of instantaneous light required, fixtures required per acre and cost of fixtures (acre/m2).We will investigate integrating lighting maps (or use all TMY3 locations) to estimate the number of hours of supplemental light needed for any location. We will expand use of tomato plant growth simulation to lettuce (Pascale model) and are investigating other plant models for simulation.We will incorporate time series solar generation data as an input and will build in models of energy consumption. We will work to scale up or otherwise improve lighting control in commercial operations and to further develop imaging technologies in commercial operations. The team working on life cycle analysis (LCA) will collaborate with other team members and industry partners to access manufacturing data and expand resources for improving LCA calculations using SimaPro. We will identify system boundaries, using reliable data for unique products/services, interpreting environmental/human health products, and translating results into grower recommendations. Life-cycle cost analysis (LCCA) will be used to determine the economic impact of lighting choices such as the cost difference between LED and HPS fixtures. We will expand and incorporate LCCA into some of our calculator tools. More sophisticated modeling with LCCA will be performed involving the economics team. We will be working on LED light spectrum controls and involve a testbed to monitor the effect of light intensity and spectrum control together. In these studies, we will implement a proposed method in a greenhouse environment and test the prediction-based method in commercial CEA production with collaborators. For Virtual Grower, we will update the "Lighting Setup" section. This will involve collaboration with LAMP research teams to incorporate research models into VG as data becomes available. With our economics team we will develop simulations on the demand side and will simulate prices for certain crops and energy. A net present value (NPV) and internal rate of return (IRR) analysis will be performed for various lighting installations over 10 years. Our goal is to determine the greatest profitability and identify areas where slight, realistic changes may cause profit to change noticeably over the length of the planning horizon. We will perform a survey of 4000 consumers in the US. They will be randomly picked through our database. There will be questions about demographics, price, quality. We will assess how far they live from greenhouses and if they have issues with the industry (ex. Lighting pollution). If adverse social components are determined we can look for options to manage/fix these aversions. Impact evaluation will be involved in the survey process. Additionally, the impact evaluation team will survey 9 team members (3 coPIs, 3 advisory board members, 2 GRAs and 1 postdoc) for continued evaluation of the project team. Participation evaluations will also continue at meetings, outreach events, and through online sources such as OSF, etc. Following Outreach events, we will be performing satisfaction surveys. We will deliver information to the PD and project manager to go over data for continuous improvement. We will continue to work with growers, our outreach program, research teams and our advisory panel to develop decision tools to assist growers with production. Communications within our organizations will be used to provide press releases for different aspects of the project. We will continue to maintain our webpage and will actively pursue the use of the LinkedIN page. Field trips where we are planning or performing on-farm trials will continue. Once updates are provided to Virtual Grower, we will incorporate this into industry training sessions. We will continue to connect to individuals in the CEA industry at conferences such as Cultivate. We will be performing an industry survey with AmericanHort through Jill Calabro to get information from growers for webpage content and to further direct us as we develop outreach material. We are going to work with our graduate students to get 3-6 articles developed for a series to publish in a trade journal. We will continue to provide webinars and post those to our website and social media platforms. Towards the end of the next reporting period we will plan hands-on industry training programs for various components of the project (i.e. lighting fixture set up, use of decision-support tools).

Impacts
What was accomplished under these goals? Impact:We found that far-red light is as photosynthetically active as traditionally-defined photosynthetically-active light (440-700nm), while increasing canopy size & canopy light interception. As a result, inclusion of far-red light in lighting fixtures can increase growth of many crops under sole-source lighting (but not in greenhouses with supplemental lighting). We developed hardware & software to determine in real-time how much supplemental light to provide to greenhouses crops. Based on these algorithms, the system can control LED lights to assure a crop gets the amount of light it needs. Goal 1. Lighting strategies to optimize crop growth & quality in cost-effectiveways. We had ongoing plant physiology work into YR2, performing work to assess DLI/PPFD/photoperiod manipulation indoors & in greenhouses, far-red effects on indoor production, and quantifying light use efficiency. Far-red light studies show improved growth and root development. Far-red may have potential to shorten crop cycles. Replacing part of the white light with far-red in indoor production can speed up growth. We've shown that far-red & white light have equal photosynthetic activity (if the far-red does not make up more than about 25% of total photon flux). In addition, far-red can stimulate leaf elongation, allowing the plant to capture more light. The combined photosynthetic & canopy size effects of far-red make far-red photons about twice as effective in stimulating growth as photons in the 400 - 700 nm spectrum. Studies involving supplemental light with longer photoperiods, but the same total amount of light per day, showed increased growth, improved root development, and shortened cropping cycles by at least 1 week. In growth chambers, we performed studies to determine the effects of dynamic LED sole-source lighting on propagation and finishing. End of day applications with far-red were used to see if increased leaf expansion occurred early in production. We are studying the use of UV-a light to manipulate growth on phytochemical content of plants. We are also evaluating why plants might acclimate to elevated CO2 over time. We are investigating if we can standardize or normalize spectrum for our studies. Two potential targets for testing: leaf photosynthesis & leaf expansion. We could investigate spectra & see how this modeling works with different lights. Goal 2. Lighting controllers that can automatically implement these strategies. We initiated on-farm trials involving adaptive lighting controls based on current sunlight & target DLI. James Greenhouse studies indicate measurably more uniform & faster rooting across the tray in roses. They saw a stronger start in growth with reduced liner crop time by a week. If higher lighting levels than needed were used, plants were easily torched. Work in engineering resulted in a model predicting sunlight using historical data using a Markov model. This sunlight prediction is used to find the optimal lighting strategy. The algorithms were developed & tested using historical weather data and implemented in a testbed environment using a Raspberry Pi. Goal 3. New sensing technology for monitoring crop growth and physiology. We developed an imaging system that utilizes chlorophyll fluorescence for crop imaging in controlled environments. The system uses blue light to excite chlorophyll in the plants, which fluoresces in the red part of the spectrum. A camera with a long-pass filter takes images of the fluorescence emitted by the plants. This provides a simple way to take images of the canopy & has proven to be an effective method to non-destructively monitor crop growth. We have shown this system can detect certain stress responses in plants well before any visible symptoms. We are working on a system that uses chlorophyll fluorescence to measure the photosynthetic activity of plants. Two principles were tested: fiber optic and free-space optics. With fiber optic, the advantage was ease of optical alignment inside the instrument. With free-space optics, the alignment was extremely difficult but advantageous was the ability for sensing at a distance (1-2 meters). We are investigating development of a scanning free-space system. The fiber-optic system is fully functional and has been integrated into a system that can measure photosynthetic activity & adjust lighting intensity based on those data. Goal 4. Software to assess whether use of supplemental lighting is economical. We continued developing lighting cost calculators, using MIS students to work on TMY3 data. An additional, simplified calculator was developed containing weather files & 4 inputs with monthly electrical lighting data from different locations. A ag econ GRA worked on evaluating the cost of lighting using localized electrical costs with the calculators. We have investigated economic additions spread over 10 years combined with an estimated installation cost for the LED fixture. We developed simple budgets starting with installation costs making comparisons of LED, HPS and no lighting. We continued work to developed a prototype R-based system that uses TMY data allowing users to indicate location & greenhouse design to calculate electricity costs. Ongoing work for a plant growth simulator uses the TOMSIM (Heuvelink, E.) or TOMGRO model. This simulator involves relationships between crop growth, environmental conditions, energy consumption and renewable energy generation to allow a range of operating scenarios simulation for quantities comparison studies. Current work involves uploading TMY3 data into the influxDB (database), setting up visualization and determining a host application for web deployment. Report generation was accomplished in the following formats: downloadable PDF, spreadsheet or an online visual of the original output. Also available are charts and tables generated on the website within the simulator dashboard. Goal 5. Software and hardware to implement cost-effective lighting strategies. A GRA in engineering initiated work on life cycle assessment (LCA) of supplemental lighting systems used in CEA. For this study, SimaPro software was used to collect, analyze and monitor LCA of supplemental lighting systems. The software includes libraries and databases to assess the life cycle from cradle to grave. Software challenges were identified including defining system boundaries, finding reliable data for unique products/services, interpreting environmental/human health products, and translating results into grower recommendations. (Also see goal 2). Goal 6. Software to simulate different lighting scenarios (Virtual Grower, with USDA-ARS). An engineering student is quantifying the effects of using LED lighting compared to conventional lighting systems on the thermal balances, heating loads and air circulation patterns within a greenhouse to integrate this information into Virtual Grower. USDA-ARS received permission to hire an IT support position to initiate programming changes to Virtual Grower for the project. That hire is anticipated to be completed during this reporting period. Goal 7. Impact assessment. The IEU GRA performed ongoing evaluations of the project and team capturing information related to project activities, collaborations, and publications. They are observing the team at meetings, on field trips, interviews and audience satisfaction surveys following outreach activities. A social network analysis was completed to look at how team/group connections contribute to scholarship. This network analysis assesses the following: 1) how did previous associations among PIs impact future work, 2) what impact did networks have on scholarship productivity, 3) how did LAMP funding impact network development, 4) how did the investment in graduate research associates harness the intellectual capital of emerging scholars, and 5) which social ties influenced scientific performance the most?

Publications

  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Palmer, S. 2020. Photoperiodic effects on growth, photosynthesis, and biomass allocation in leafy vegetables in controlled environments. MS thesis, University of Georgia, Athens, GA.
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Weaver, G. 2019. Lighting control strategies for improved photochemical efficiency in controlled-environment agriculture. PhD Dissertation, University of Georgia, Athens, GA.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Weaver, G. and M.W. van Iersel. 2020. Longer photoperiods with adaptive lighting control can improve growth of greenhouse-grown Little Gem lettuce (Lactuca sativa). HortScience 55:573-580. https://doi.org/10.21273/HORTSCI14721-19.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: van Iersel, M.W., G. Weaver, R. Legendre, and C. Kim. 2020. Converting light into biomass: quantifying the conversion efficiency. Acta Horticulturae (in press).
  • Type: Other Status: Published Year Published: 2020 Citation: Marabesi, A. O., & Kelsey, K. D. (2020). Formative evaluation of Lighting Approaches to Maximize Profit (LAMP): Year 1 2019-2020 [Unpublished manuscript]. Impact Evaluation Unit, University of Georgia.
  • Type: Conference Papers and Presentations Status: Submitted Year Published: 2020 Citation: Eylands, N. and N.S. Mattson. 2020. Influence of far-red intensity during the seedling stage on photomorphogenic characteristics in leafy greens. Abstract and presentation submitted to Annual ASHS Conference. Orlando, FL, August 9-13, 2020.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: A. Salazar; A. Berzoy; W. Song; J. Mohammadpour Velni. 2020. Energy Management of Islanded Nanogrids Through Nonlinear Optimization Using Stochastic Dynamic Programming. IEEE Transactions on Industry Applications. 56(3): 21292137. https://doi.org/10.1109/TIA.2020.2980731
  • Type: Conference Papers and Presentations Status: Submitted Year Published: 2020 Citation: Mosharafian, S., S. Afzali, J. Mohammadpour Velni, and M.W. van Iersel. 2020. Development and implementation of a new optimal supplemental lighting control strategy in greenhouses. Proceedings of the ASME 2020 Dynamic Systems and Control Conference (in press).
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Zhen, S., B. Bugbee. 2020. Far-red photons have equivalent efficiency to traditional photosynthetic photons: Implications for redefining photosynthetic radiation. Plant Cell and Environment. Plant, Cell & Environment. 43(5). https://doi.org/10.1111/pce.13730.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: Kusuma, P., P. Pattison, and B. Bugbee. 2020. From physics to fixtures to food: current and potential LED efficacy. Nature-Horticulture Research. 7:56. https://doi.org/10.1038/s41438-020-0283-7.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Liu, J. and M.W. van Iersel. 2020. Effect of light quality on green lettuce leaf photosynthetic activity interact with light quantity. 1st Virtual Eastern Region Photosynthesis Conference (37th ERPC).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: van Iersel, M.W. 2020. Lighting approaches to maximize profits. GLASE webinar. Available at https://glase.org/webinars/lighting-approaches-to-maximize-profits/
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Clutter, M. 2020 An economic assessment of dynamic LED supplemental lighting installations in greenhouse production. MS thesis, University of Georgia, Athens, GA.
  • Type: Journal Articles Status: Other Year Published: 2020 Citation: Marabesi, A. O., & Kelsey, K. D. (2020, in preparation). An evaluation of social networks within National Institute of Food and Agriculture funded projects. Advancements in Agricultural Development.
  • Type: Theses/Dissertations Status: Published Year Published: 2020 Citation: Elkins, C. 2020. Evaluation of different lighting strategies used to improve efficiencies in plant growth for controlled environment agriculture. MS thesis, University of Georgia, Athens, GA.


Progress 08/01/18 to 07/31/19

Outputs
Target Audience:Target audiences we have reached include: Controlled environment agriculture industry (greenhouses, plant factories) Commercial lighting companies University and non-university scientists Graduate students Changes/Problems:Dr. Tessa Pocock has resigned from Rensselaer Polytechnic Institute (RPI) and RPI no longer has a plant scientist qualified to participate in this project. We are in the process of reallocating those funds and responsibilities and will add Joshua Craverto our project team to fill this gap. What opportunities for training and professional development has the project provided? At the University of Georgia (UGA), eight graduate students, three undergraduates, and one technician in the Horticulture Department participated in this project and were exposed to the latest in LED technology and had the opportunity to study plant responses to different lighting strategies. Two of the undergraduates got hands on research experience. A team of three senior statistics undergraduates performed their capstone project to help our project. They got experience in handling large data sets and running simulations. A graduate student was selected and began training in evaluation research. She will attend the annual American Evaluation Association conference in November 2019 to learn more about the profession. In Mechanical Engineering, an undergraduate research student gained experience in working with CFD modeling software and took an HVAC course at the graduate level in Spring 2019. This student is continuing to work on Project LAMP over the next year as a graduate student. Two othergraduate students in engineering at UGA were supported by the project. One student (MS in Electrical Engineering) was primarily responsible for pulse-amplitude chlorophyll fluorescence measurement. The second student (MS in Biological Engineering) was responsible for the plant imaging chamber.The unique opportunity for these students is the interdisciplinary nature of the research project. As engineering students, they get exposed to plant physiology and horticulture. At Cornell University, a PhD student joined the project in January and has studied plant responses to far-red lighting strategies. The student has gained experience in research light construction, light distribution mapping, use of spectroradiometer to quantify light quality and quantity including calculations and conversion units. Two undergraduate students have been trained in processing large national lighting data sets to estimate supplemental light requirements. Their work includes coding in the computer language, Python. At Utah State University, two graduate students and five undergraduate students worked with the latest technology and learned research techniques to plant responses to lighting. For the project, we initiated an annual meeting early this year. It was hosted at the University of Georgia and included our project directors,co-PIs, graduate students,post-docs and our advisory panel. We involved this same group in quarterly meetings which are shorter in time and allows project participants to gain continuous input from our advisory panel to our research and outreach teams. For the quarterly meetings we use web-based videoconferencing to facilitate communication with our teams throughout the US. A significant number of the project participants are located at the University of Georgia so we have implemented monthly in person meetings with co-PIs and graduate students to facilitate communication and collaboration. These meetings allow for all of our project participants to share scholarly information thereby providing professional development for our research teams, our outreach team and our industry partners.Graduate students get to see first-hand how large research projects are managed. How have the results been disseminated to communities of interest? Results have been published in peer-reviewed journal articles and conference proceedings and have been presented at scientific meetings [USDA regional project NCERA-101 Controlled Environment Technology and Use; American Society for Horticultural Science (webinar and conference proceedings)] and grower meetings (Cultivate). We established a research update page on our website (www.hortlamp.org) and began reporting one page updates on studies we have run for the project. Those research updates are also being posted to our Facebook page as part of our outreach initiative. What do you plan to do during the next reporting period to accomplish the goals? Our current lighting control system is expensive, we plan to develop low-cost versions in year 2 and will implement this control suystem in at least one commercial greenhouse. We will equipan imaging chamber with a variable filter set that allows us to apply either a chlorophyll fluorescence imaging protocol or the imaging protocol for the projected plant area (i.e., growth monitoring). The purpose is to automate and integrate our method for plant area imaging into the existing system. We will investigate differentlighting strategies, includingincorporationfar-red light into seedling growth stage. By supplementing with threedifferent intensities of far-red (via LEDs) to a white LED background at 3 different durations, weanticipatea photomorphogenic response that increases leaf area/canopy size at seedling stage. We expect to see an increase in light capture & photosynthetic rates when the plants are subsequently transplanted. Initial experiments involve 3 cultivars of lettuce with a goal of either increase harvest plant size or reducing days to harvest leading to increased economic returns. Other lighting strategies to be tested include adaptive lighting (in response to sun light) and manipulating photoperiod to control crop growth and flowering. Our Master of Business Technology student teams (two sets of 5) will develop software to help greenhouse owners plan for the climate and operate based on the weather to determine lighting needs and minimize energy costs subject to production schedules. This aspect of the project will be in collaboration with our engineering team to integrate their results into the algorithms of our simulated lighting systems. As part of this process, a spreadsheet tool will be developed to allow a life-cycle cost comparison of supplemental lighting systems. The life-cycle cost calculations are based on the NIST 135 standard used in FEMP (Federal Energy Management Program), a common methodology for evaluating financial feasibility of energy efficiency measures in buildings. NIST 135 includes adjustments for energy price indices, inflation, & time value of money. This tool will enable growers to make more informed business decisions than with simple payback alone. One of our engineering students will look at the effects of using LED lighting compared to conventional lighting systems on the thermal balances, heating loads and air circulation patterns within a greenhouse to integrate this information into Virtual Grower. Another engineering student (MS in Biological Engineering) will be focusing on imaging methods for plant growth studies. On-farm trials with adaptive lighting will be started with James Greenhouses, allowing us to test different lighting strategies at a commercial scale. We will take an existing greenhouse tomato crop growth model (TomSim, developed at Wageningen University in the Netherlands) and convert it to a web-based app. The goal is to allow any thrird party users to simualte different lighting stragies and to determine how that will impact tomato yield. Creation of a web-based app will make the model accesible to a wide audience. Our Impact Evaluation Unit will perform an assessment of our research teams and submit an evaluation report of initial findings of our current collaborative efforts.

Impacts
What was accomplished under these goals? Impact. We found twoways to lower lighting costs for more profit & sustainability. 1.Spread the same amount of light out over more hours per day to allow plants to use light more efficiently for growth. 2.For indoor production, add up to ~20% far-red light to white LED light to increase growth efficiently. Goal1. Lighting strategies to optimize crop growth & quality in cost-effective ways. We determined that providing a certain amount of total light (DLI, daily light integral) stimulates crop growth more when provided over longer periods with lower intensities. This question common lighting recommendations for horticultural crops. Lighting requirements are typically based on DLI. With the DLI spread out over a longer time period (photoperiod) crops grow faster. For growers, using a longer photoperiod & the same DLI speeds up crop growth. Also, if growers switch to longer photoperiods, they could use lower instantaneous supplemental light intensities to achieve the same growth rate. This allows for fewer installed lights, lowering lighting capital expenses. Many LED indoor grow lights use white or red & blue LEDs. We have shown that adding far-red light tothe spectrum increases leaf elongation & photosynthesis. When replacing up to 20% of white LEDs with far-red LEDs, far-red stimulates crop growth 3x more effectively than the some amount of white light. This allows for the development of more effective growth lights. We have only seen the benefits of far-red light in indoor production settings, not greenhouses. Canopygas exchangestudies demonstrate that the far-red photons from far-red LEDs are photosynthetically active. This has profound implications for crop productivity. Manufacturers can add far-red LEDs to their fixtures intended for sole-source lighting. In studies with multiple species, we found that adding far-red light was beneficial on leaf expansion in lettuce but was not beneficial in other leafy greens like spinach. In tomatoes & cucumbers, the addition of far-red significantly increases stem elongation more than leaf expansion, and thus is detrimental in crops where increased plant height is undesirable. We have shown that providing supplemental light when there is little sunlight results in better growth than providing that light with ample sunlight. This provides new opportunities for control of LED lighting systems: simple algorithms & light sensors can be used to determine how much supplemental light to provide at which time. Based on decades old research conducted at very low light levels, green light is considered less photosynthetically active than red or blue light. We have found at low light intensities blue and green light have similar photosynthetic activity, lower than that of red light. However, at high light intensity green light has similar photosynthetic activity as red light & higher than that of blue light. These results show the photosynthetic value of green light is underestimated. Use of supplemental/sole source lighting at a growth stage in which plants are most densely populated (such as seedling or liner stage) allows for cost effective lighting.Advances in the conversion of photons to yield can be achieved by optimization of spectral effects on plant morphology.We are elucidating unique morphological responsesand optimum spectra vary among species. Goal2.Lighting controllers that can automatically implement these strategies. We developed hardware to automatically implement optimal lighting strategies with dimmable LED lights. The hardware uses dataloggers, light sensors and a simple algorithm to determine the amount of supplemental lighting. The system then produces a signal sent through a dimmable driver to control the supplemental light provided. We have developed an optimal framework to minimize total light provided from supplemental LED lights with variable intensity to reach a specified daily amount of photochemistry within a specified photoperiod. The proposed approach minimizes the electricity required because light (PPFD) output of LED lights is directly proportional to electricity consumption when dimming is accomplished using pulse width modulation (PWM). Acomputationally-simplesolution to this problemwas developed to facilitate real-time implementation. Goal 3. New sensing technology for monitoring crop growth and physiology We have developed an imaging system that takes advantage of the fluorescent properties of chlorophyll. When leaves are exposed to light, they give off a small amount of red and far-red light. This can be detected using a camera with a filter. Our system uses a blue LED light and monochrome camera. The filter prevents blue light from being detected while the camera detects fluorescence from the plant. This results in gray-scale pictures with the background dark and canopy as different levels of gray. We developed a pulse-amplitude method for measuring chlorophyll fluorescence with the ability to serve as electron transport rate sensor for a lighting control system. With this method, we developed a low-cost prototype for point measurement of chlorophyll fluorescence & Photosystem II quantum yield. We also designed an imaging chamber to test plant-scale chlorophyll fluorescence imaging. The imaging chamber is equipped with controllable actinic lights, high-power white light and blue measurement light sources. We are testing general imaging capabilities of the chamber & developing control software for pulse-amplitude chlorophyll fluorescence imaging. The chlorophyll fluorescence sensors are equipped with an interface that controls the dimmable LED drivers. 4. Software to assess whether use of supplemental lighting is economical A GIS mapping tool was developed to allow visualization of data related to supplemental lighting requirements in greenhouses. First weather data files such as TMY3 (typical meteorological year) are parsed and processed to determine daily supplemental PAR (photosynthetically active radiation) required to meet a specific DLI target. Glass or double poly glazing determines natural light transmittance. Daily values are summed to produce an annual requirement of supplemental light. Data comes from 1,020 TMY3 stations in the US. Using bilinear interpolation of station latitude/longitude the data can be visualized on a heat map to see where supplemental light requirements are highest. We have 10 students developing software to help greenhouse owners plan for the climate and operate for the weather to determine lighting needs and minimize energy costs subject to production schedules. We continue to refine a spreadsheet return on investment calculator that graphically shows the breakeven point for adding supplemental lighting. The inputs are the efficacy of the fixture, fixture lifetime, cost of electricity and cost of the fixture. 5.Software/hardware to implement cost-effective lighting strategies. We have developed a simple algorithm to determine the best way to provide supplemental light in greenhouses. It takes into account time of day, typical distribution of daily sunlight and current light levels. The algorithm used determines how much supplemental light to provide at any specific time and is easily implemented into control systems. 6.Software to simulate different lighting scenarios (Virtual Grower with USDA-ARS). We developed a study to compare thermal balances, heating loads and air circulation in greenhouses with LEDs and conventional lighting systems. We will use this information to improve Virtual Grower. ?7.Impact assessment. We initiated impact evaluation efforts with meeting attendance for assessing the research teams.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Weaver, G.M., M.W. van Iersel, and J. Mohammadpour Velni. 2019. A photochemistry-based method for optimizing greenhouse supplemental light intensity. BioSystems Engineering 128:123-137.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Weaver, G. and M.W. van Iersel. 2019. Photochemical characterization of greenhouse-grown lettuce (Lactuca sativa L. Green towers) with applications for supplemental lighting control. HortScience 54:317-322. https://doi.org/10.21273/HORTSCI13553-18
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: van Iersel, M.W. 2019. Optimizing supplemental lighting in greenhouses. From physiology to crop growth. Department of Environmental Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: van Iersel, M.W. 2019. Converting photons into biomass. Implications for controlled environment agriculture. Department of Horticulture, University of Georgia, Athens, GA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: van Iersel, M.W. 2018. Converting photons into biomass. Implications for controlled environment agriculture. American Society for Horticultural Science webinar.
  • Type: Theses/Dissertations Status: Published Year Published: 2019 Citation: Weaver, G.M. 2019. Lighting control strategies for improved photochemical efficiency in controlled-environment agriculture (PhD dissertation).
  • Type: Websites Status: Published Year Published: 2018 Citation: Lighting approaches to maximize profits. www.hortlamp.org.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Palmer, S. and M.W. van Iersel 2019. Biomass allocation in three subspecies of Brassica rapa grown hydroponically in a greenhouse. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Reese, L.E. and M.W. van Iersel. 2019. Effects of varying light intensity on instantaneous water use efficiency in lettuce and petunias. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Weaver, G. and Marc W. van Iersel. 2019. An effective algorithm for controlling greenhouse light to a target daily light integral using dimmable supplemental lights. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Liu, J and M.W. van Iersel. 2019. Green light benefits photosynthesis at high light level. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Jayalath, TC and M.W. van Iersel. 2019. Supplemental lighting for biomass increase of cilantro and basil plants. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Legendre, R. and M. van Iersel. 2019. The effect of supplemental far-red light spectrum on the canopy size of lettuce (Lactuca sativa). Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Elkins, C.A., M. Martin, and M.W. van Iersel. 2019. Growth and morphological responses of Digitalis and Rudbeckia seedlings to supplemental far-red led light. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Kim, C. and M.W. van Iersel 2019. Morphological and physiological screening for growth differences among 11 lettuce cultivars. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Narayanan, M., M.W. van Iersel, and M. Haidekker 2019. Chlorophyll fluorescence imaging: a novel, simple and non-destructive method for canopy size imaging. Annual Conference of the American Society for Horticultural Science. Las Vegas, NV.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: van Iersel, M.W. and N.S. Mattson 2019. Lighting Approaches to Maximize Profits (LAMP). Cultivate July 2019, Columbus OH.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bower, K., Kelsey, K. D., Marabesi, A. O., & Dossou-Kpanou, M. (2019). Integrating the guiding principles into our Impact Evaluation Unit: Qualitatively exploring our subjectivity through the AEA guiding principles. American Evaluation Association. Minneapolis, MN, November 11-16, 2019. Round table.
  • Type: Conference Papers and Presentations Status: Under Review Year Published: 2019 Citation: Shelford, T., C. Wallace and A.J. Both. 2019. Calculating and Reporting Key Light Ratios for Plant Research. Presented at the GreenSys 2019 meeting in Angers, France and submitted for publication in Acta Horticulturae.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Pattison, M., J. Tsao, G. Brainard & B. Bugbee. 2018. LEDs for photons physiology and food. Nature 563: 493-500. DOI:org/10.1038/s41586-018-0706-x
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bugbee, B. 2017. Economics of LED lighting. In: S.D. Gupta (ed.). Light emitting diodes for agriculture. Smart lighting. p. 81-99. Springer Verlag, Singapore. (ISBN 978-981-10-5807-3) doi.org/10.1007/978-981-10-5807-3_4