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%
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.