ALASKA GREENHOUSE AND CONTROLLED ENVIRONMENT PRODUCTION USING LEDS AND OTHER EMERGING TECHNOLOGIES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1016282
• Project Start Date: Oct 1, 2018
• Project End Date: Sep 30, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF ALASKA
(N/A)
FAIRBANKS,AK 99775

Performing Department
Agriculture and Horticulture

Non Technical Summary
The interest in producing food as a community or as individuals can be expected to increase as environmental and social awareness is growing. Many communities are striving for cost-effective local sustainability in respect to food, energy and water resources, health, education and employment opportunities. Controlled environment vertical farms, hydroponics and indoor growing facilities offer opportunities to locally produce food in areas with limited climate or land suited for agriculture. The intention for greenhouses and enclosed vertical indoor farming systems is to grow crops for local marketing and consumption during part or throughout the year. Strategies for production, marketing and the development of business plans in support of these local developments require sound well established research knowledge and realistic projections of crop cycles, anticipated yields, labor commitments and production costs.In greenhouse and vertical indoor cropping systems, light and lighting systems are a significant investment and ongoing expense. LEDs efficiently convert electric energy to light and LEDs are expected to entirely replace current technology for supplemental greenhouse lighting. Slim LED designs permit innovative and non-conventional configurations for the most effective use of space in horizontal or vertical production systems. LEDs also offer extended life expectancy of continuously high output and opportunities to customize the spectral quality. Studies determining the most effective LED wavelength compositions, configurations, durations and intensities are still needed in order to reach the production potential for various crops.Nutrient density along with yields and crop market value need to be considered when evaluating the efficiency of various growing systems. Only approximately five percent of the food purchased in Alaska is produced in the state. To encourage consumers to preferentially seek out Alaska grown over brought in produce, data documenting quality advantages would justify maintaining and increasing local production of produce and marketing of higher priced Alaska grown produce.

Animal Health Component

90%

Research Effort Categories

Basic

10%

Applied

90%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
205	1499	1060	100%

Knowledge Area
205 - Plant Management Systems;

Subject Of Investigation
1499 - Vegetables, general/other;

Field Of Science
1060 - Biology (whole systems);

Keywords

greenhouse

vertical farming

indoor growing

urban farming

hydroponics

led

nutrient density

Goals / Objectives
Food security is a major issue for Alaska. Short field seasons and challenging climatic conditions result in variable and often limited supplies of local produce with high dependency on food brought in from outside (Karlsson, 2017, Meter and Goldenberg, 2014). The substantial distance to large agricultural production areas raises concerns for interference in delivery systems and year-round availability of affordable high quality food. Enhancing local production to reach some degree of self-sufficiency is therefore desirable. Legislative efforts establishing food security task force committees, working groups, policies and attempting to stockpile food resources have not led to long-term sustainable food security solutions for the state. Developing and maintaining regional food production, processing and distribution appear to be a more dependable approach.Field enhancements to improve and extend the season, and intensely managed greenhouse systems improve the flow of produce over the year compared to unbalanced large single crop seasonal harvests followed by prolonged periods of no local production. Moderate temperatures, low relative humidity and isolation from large established agricultural production areas reduce the risks for contamination and outbreak of serious crop diseases and pests. Since crop production and climatic resources are intensely managed in these settings, more detailed understandings of crop development, cultural techniques, and harvest distribution patterns are needed than the often well-documented progression of traditional field grown crops. Alaska research, education and outreach programs concentrating on high tunnel-, greenhouse- and controlled environment production systems have not kept pace with the need for training, new technologies, non-traditional crops, the growth of the industry, and implementation of site-specific management.The efficiency of LEDs in various arrangements for hydroponic vegetable production will also be evaluated. Lettuce, leafy- and mustard green crops are well suited and now commonly grown in vertical indoor production systems (Kozai, 2013; Kozai et al., 2016b). A re-circulating hydroponic system will be set up using 240 cm (8 feet) long SURE GRO® NFT channels (width 100 mm x 40 mm height, CropKing, Seville, Ohio) of UV-stabilized white PVC. A butterhead type cultivar developed, bred and recommended for hydroponics such as 'Charles' will be selected. In addition, a leaf lettuce (such as Red Sails) and a romaine lettuce (for instance Parris Island Cos) will initially be evaluated. The seed will be germinated in one square inch rockwool cubes at 68°F (20°C) and 16 daily hours of 200 to 250 µmol?m-2s-1. Ten days from seeding, the rockwool cubes and seedlings will be transferred to the pre-drilled square holes of the channel. Twelve plants spaced 20 cm apart (center to center) can be accommodated in each channel. From the center of each channel, the spacing will be 20 cm between channels. The growing area for each plant is 20 x 20 cm or 25 plants?m-2.The hydroponic system is a closed NFT system with the nutrient solution returning to a stock tank after passing through the channels (Cooper, 1996). The stock tank is continuously reloaded and monitored for nutrients, pH and electrical conductivity using the on demand dosing system NutriDose II (Autogrow Systems, American Hydroponics, Arcata, California). A hydroponic fertilizer (Chem-Gro lettuce formula 8-15-36, Hydro-Gardens, Colorado Springs, Colorado) augmented with calcium nitrate (CaNO3) and magnesium sulfate (MgSO4) will be used initially to provide a nutrient solution of nitrogen at 140 ppm, phosphorus at 40 ppm, potassium at 180 ppm, calcium at 120 ppm, magnesium at 75 ppm, sulfur at 100 ppm and micro-nutrients. The pH will be maintained at 5.5 to 6 and the electrical conductivity at 1.5 to 2 dS m-1.Various LEDs will be evaluated including the traditional red/blue combination along with other monochromatic LEDs. The effect of adding green (~ 565 nm) or far-red (~ 730 nm) LED light will also be studied. Light levels will be monitored using a LI-1400 data-logger with several LI-190 quantum sensors and the spectrum with a SPEC-PAR/UV 300-850 nm (Apogee Instruments, Logan, Utah). Light will be provided for 16 daily hours at 230 to 250 µmol?m-2s-1 (15 to 16 mol·d-1m-2).Several types of lettuce, leafy-, and mustard greens will be evaluated. The leafy crops will be harvested when judged mature for marketing after 28 or more days (United States Department of Agriculture 1997; 2016). Morphological overall height and width will be measured. Fresh weight of tops and roots will be recorded along with dry weights after 3 days of drying at 158°F (70°C). Leaf area will be recorded using a LI-3100C leaf area meter (LI-COR, Lincoln, Nebraska). As an indication of sugar content, Brix analysis will be used. In addition, the mineral nutrient content of P, K, Ca, Mg, Fe and Zn will be evaluated in sampled leaves using an ICP-OES instrument (Agilent ICP-OES 720-ES). This instrument is suitable for these types of studies and is available for use in the project.Cultivars of sweet bell peppers will be evaluated for northern greenhouse production. Selections that ripen to red, orange or yellow colored peppers will be included. Seeds will be germinated in containers of 256 mL volume filled with a peatlite medium (Pro-Mix BX) at a germination temperature of 72 to 75°F (22 to 24°C).

Project Methods
A state-of-the-art greenhouse facility on the UAF campus, the Arctic Health Research Greenhouse (AHRG) that was completed in 2014 will be used for the project. This facility has 420 m2 (4,500 ft2) of growing space in seven greenhouse sections for testing production systems, identify crops and cultivars, and conduct research on various aspects of crop development, growth and productivity. The greenhouse is covered with an acrylic plastic material (DEGLAS®, Degussa, CYRO Industries, Parsippany, NJ). The greenhouse facility is equipped with misting for humidity control, overhead lighting, several levels of heating including floor heat, and energy/shade curtains. All systems are controlled and monitored by a greenhouse environmental computer. The AHRG is an unprecedented opportunity to conduct high caliber research that is specifically designed to address Alaska conditions and meet local needs for greenhouse, vertical farming and controlled environment information.Spinach is chosen as a model crop for determining general plant responses to spectral light energy distributions of monochromatic LEDs. Spinach is a leafy green with consumer appeal. Results can be expected to have immediate applications in commercial production, gardening activities and for scientific inquiries. The long day flowering response presents special challenges when grown as a leafy green during northern summer seasons. Although not desired in production, the spinach flowering response provides unique research opportunities. Discrete LED lighting conditions may influence the photoperiodic response to allow studies related to flower initiation and development in long day plants.Growth patterns will be recorded for spinach and other leafy greens grown in environments with light from panels of red LEDs (peak at 630 and 660 nm) supplemented with blue LEDs (peak at 450 nm), blue (450 nm), red (630 and 660 nm), and white LEDs (5000 K). As the project advances, treatments are likely to be modified based on recorded findings. The delivery periods of light during the 24-hour daily cycle may vary and the impact and function of green (550 nm) or far-red (730 nm) spectral energies may be included. LED technologies are expected to continue to advance and become more efficient and functional for crop production. Additional LED combinations and arrangements are therefore likely to be evaluated based on trends in indoor farming systems and automated controlled environment production techniques.Data will be collected on morphological attributes such as number of leaves, leaf area, and weight of fresh and dried leaves. Mineral nutrient content of P, K, Ca, Mg, Fe and Zn in leaves harvested in the various environmental conditions will be determined. The analysis will be completed using an ICP-OES instrument (Inductively Coupled Plasma - Optical Emission Spectrometer, Agilent 720-ES). Soluble solid content will be determined as a sugar concentration estimate in °Brix using a Digital Pocket Refractometer (Spectrum® Technologies, Inc., Plainfield, IL).Sweet bell peppers specifically suited for intense controlled environment production systems are now available. These peppers are harvested at maturity with 80 to 90 percent color formation. Peppers will be used as an example crop for greenhouse fruit vegetables commonly grown trellised and pruned for space utilization and productivity. A high-wire drip irrigation system will be used to evaluate training, cropping and other management techniques.As technology advances and the scientific understanding of plant physiology increases, implementation and opportunities for more efficient crop production can be expected. Therefore during the multi-year span of this project, the procedures will adapt to new available technologies, innovations and advancements. Consumer preferences are also likely to change with requests for additional or different crops and production methods. The exact procedures and methods are therefore expected to change and adapt as this project advances.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Higher education students, state and national researchers, extension personnel, commercial producers, community members. Changes/Problems:The pandemic has reduced in-person activities and the connectivity with students and the public. Virtual and online opportunities have been engaged and used where possible. Combinations of traditional communication lines with those developed during the pandemic are anticipated to work well and more effectively for outreach and dissemination of information in the future. What opportunities for training and professional development has the project provided?Various communication channels are used to reach and meet the needs for information, education and training to various groups throughout the state. We are continuously communicating with producers and individuals interested in pursuing or already engaged in the use of various production systems such as fields, high tunnels, greenhouses and indoor controlled environments. Training opportunities in topics related to horticultural production are regularly offered and presented to students at secondary and post-secondary levels. Presentations are also provided at local, regional, national and international meetings, conferences and workshops on crop production in various environments including greenhouses, high tunnels, season extension techniques and field conditions. The limited in-person contacts and meetings in 2020 changed and reduced the number of direct interactions. As communities and the university are hopefully able to resume activities and events in 2021, traditional interactions along with online tools for training and development are likely to continue and increase. How have the results been disseminated to communities of interest?Presentations are provided at local, regional, national and international meetings, conferences and workshops on crop production in various environments including greenhouses and other indoor growing approaches, high tunnels, season extension techniques, and field conditions. In the fall of 2019 and early 2020 prior to the pandemic, activities and conferences were conducted on schedule. As in-person events were reduced or canceled in 2020, online opportunities increased. Several conferences, workshops and meetings went online with opportunities for participation, presentations and the display of research findings and information. What do you plan to do during the next reporting period to accomplish the goals?We are continuing the initiated studies and are adapting research protocols based on earlier findings to more effectively use the available greenhouse research facility. The setup for the LED research is updated for improved efficiency. Our outreach efforts are anticipated to go back to events similar to those provided prior to March 2020 along with methods that worked well during the pandemic to provide information at grower gatherings, response to information requests, scientific and producer oriented publications, and formal instructional secondary and post-secondary activities.

Impacts
What was accomplished under these goals? Spinach is a popular leafy green with a public perception of providing higher nutritional quality than many other salad greens. Flower initiation and bolting occur under long day conditions resulting in limited or discontinued leaf formation. Cultivar selections of spinach with less tendency for flower initiation under long days or warm growing conditions are available. Field production can nevertheless be limited, as many cultivars still tend to form flowers under less than optimal temperature or photoperiodic conditions. To meet year round requests for locally grown high quality spinach, shifting from field production to greenhouses and other controlled environments is an option. Light emitting diodes offer opportunities to design spectral environments in support of productivity and nutritional quality. The impact of light quality on soluble solids content (°Brix), yield, dry matter accumulation and mineral nutrient content in fresh spinach were evaluated. Spinach was grown under panels of LEDs and compared to greenhouse growing conditions with natural or supplemented light. The cultivar Seaside was selected as it has a more limited tendency to initiate flowers and bolt. The light quality treatments included blue LEDs (peak emission at 450 nm), red LEDs (50:50, peaks at 625 and 660 nm), blue/red LEDs (20:40:40, peaks at 450, 625 and 660 nm), and white LEDs (5000K). In addition, T5 fluorescent (4100 K) and natural greenhouse light supplemented with high-pressure sodium (HPS) irradiance were evaluated in a greenhouse covered with the acrylic material DEGLAS®. The growing areas of LEDs and fluorescent lamps were separated and shielded from natural and greenhouse light using an opaque blackout material. Plants were grown at a constant 21 ± 2°C with a 16 hour photoperiod at a photosynthetic photon flux of approximately 150 µmol·m-2s-1. The fresh- and dry weights were considerably smaller for plants grown in the greenhouse environment under natural and HPS lighting. Flowers formed quickly in the greenhouse grown spinach that resulted in limited leaf- and overall growth. Some spinach grown under blue LEDs also formed flowers with overall smaller fresh weights. The largest fresh weights were in the blue/red LEDs at 125.67 ± 9.16 grams per plant. The white LEDs also supported good growth (112.06 ± 4.86 g) while the red and fluorescent environments produced similar sized spinach. The proportion dry weight varied between 7.5 to 8.5 percent. The only exception was in the blue environment were the ratio of dry weight per plant was closer to 10 percent of the fresh weight. There was a trend for higher °Brix under blue LEDs with a value of 8.6 ± 0.65. To further evaluate the use and significance of LED light spectrums for growing spinach, the mineral nutrient content and quality were also determined. There were no significant differences in the content on a dry weight basis of nitrogen, calcium, iron or zinc among growing conditions. For potassium and magnesium, the highest content was recorded in the control treatment (natural light with HPS). For phosphorous, sulfur and boron on the other hand, the control treatment resulted in the least amounts. There was a trend for high values in the blue/red LED environment for manganese and copper, although not significantly different from the HPS control for copper. The 16 hour day length was used to ensure appropriate levels of daily light were provided for overall growth. Although Seaside is considered slow bolting, there was a tendency for bolting and flowering in the greenhouse environment throughout the year. The relationship between natural and HPS light is seasonally synchronized for adequate greenhouse irradiance and may influence the bolting response. The proportion for instance, of red to far-red wavelengths in the spectrum may activate flower initiation. In general, the LED environments countered or delayed flowering under the 16 hour day length to allow growth for satisfactory harvest. The only exception was the exclusively blue growing environment where flowering was observed. LEDs offer opportunities to establish a variety of temporal and spatial lighting environments to support productivity and nutritional quality of spinach. Additional studies are needed to more precisely identify the importance of the spectral energy distribution for overall growth, flowering and the nutritional quality of spinach grown in greenhouses and controlled environments. 1. Advance production and management techniques for Alaska agricultural production in greenhouses and controlled environment production facilities through novel technologies, methods and innovations. Several studies are in progress for determining the effects and potential implementations of LEDs for greenhouse and controlled environment production. Sustainable greenhouse systems that are specifically well suited and efficient for high latitude vegetable production are also evaluated. 2. Develop sustainable greenhouse control methods to improve resource use efficiency, climate uniformity, production quality, productivity and yields. LEDs with expected higher energy efficiency and adjustable spectrum, suggest improved resource use while allowing for a more uniform growing environment to support crop productivity and quality. Greenhouse production systems that are based on the extended daylight hours in the summer and transitioning into less light demanding crops during the winter can be expected more resource efficient and sustainable in northern climates. 3. Disseminate information about controlled environment technologies, methods and approaches to producers throughout the state. As we gain knowledge and understanding of LEDs and other production techniques, we anticipate additional publications and outreach efforts in this area. 4. Teach up-to-date greenhouse, indoor farming and controlled environment technologies to beginners, producers, and students in formal educational programs. In the fall of 2019, the course Applied Plant Science was offered to undergraduate students. This course had a significant emphasis on the sustainable use of resources and the management of light and other climatic conditions. The courses Principles of Sustainable Agriculture and Greenhouse Management were offered in the spring of 2020. The college level greenhouse management course includes substantial information on modern control and management techniques for greenhouses and controlled environments. Understanding and implementing greenhouse and season extension environments are essential for efficient local northern crop production. These courses were completely transitioned to online delivery mid-semester due to Covid. 5. Publish research findings, prepare educational materials, and exchange information with stakeholders, extension personnel and researchers in the U.S. and internationally Results and experiences on the efficient use of LEDs, protocols for spinach production and the nutritional value of locally grown produce and herbs have been communicated at state, national and international scientific conferences, as well as in post-secondary education and producer oriented gatherings. The annual ASHS (American society for horticultural science) meeting was held online in August of 2020. This conference provided information and several presentations on findings related to the use and adaptation of LED lighting technologies in research and crop production along with the use and implementation of controlled environment facilities for crop production in various geographic locations and climates. Although the online conference was well attended and allowed for individual and direct contacts, the interactions were more limited and an in-person meeting is more desirable. The international conference on Light in Horticulture planned for June 2020 was postponed to May 2021.

Publications

• Type: Journal Articles Status: Awaiting Publication Year Published: 2021 Citation: Karlsson, M. 2021. Light quality affects growth and nutrient content in basil. Acta Horticulturae (in press).
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Karlsson, M. 2020. Nutritional quality of locally grown Alaska produce. Alaska Sustainable Agriculture conference.
• Type: Other Status: Published Year Published: 2020 Citation: Karlsson, M. 2020. Light quality affects growth and nutrient content of spinach. HortScience 55(9):S234
• Type: Journal Articles Status: Accepted Year Published: 2021 Citation: Wilkinson, A., H. Penn, M. Karlsson, C. Gerlach. 2021. Controlled environment agriculture and containerized food production systems, part of a diversified, sustainable and resilient food system? J. Agriculture, Food Systems, and Community Development.

Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Higher education students, state and national researchers, extension personnel, commercial prodcuers, community members. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Several types of communication channels are used to reach and meet the needs for information, education and training to various groups throughout the state. We are continuously communicating with producers and individuals interested in pursuing or already engaged in the use of various production systems such as fields, high tunnels, greenhouses and indoor controlled environments. Training opportunities in topics related to horticultural production are regularly offered and presented to students at secondary and post-secondary levels. Presentations are also provided at local, regional, national and international meetings, conferences and workshops on crop production in various environments including greenhouses, high tunnels, season extension techniques and field conditions. How have the results been disseminated to communities of interest?Presentations are provided at local, regional, national and international meetings, conferences and workshops on crop production in various environments including greenhouses and other indoor growing approaches, high tunnels, season extension techniques, and field conditions. Posters of recent findings are displayed and made available at various gatherings related to university activities, educational outreach and community events. What do you plan to do during the next reporting period to accomplish the goals?We are continuing the initiated studies and are adapting research protocols to more effectively use the available research greenhouse facility. The setup for the LED research is updated for improved efficiency. Our outreach efforts include grower gatherings, responses to requests for information, scientific and producer oriented publications, and formal instructional secondary and post-secondary activities.

Impacts
What was accomplished under these goals? The nutritional content of fresh produce available to consumers in stores, at farmer markets and locally grown was evaluated in Fairbanks, Alaska. The study was conducted to determine potential differences between locally grown produce and produce available in local stores from various sources. The included vegetable crops were tomatoes, colored bell peppers, English cucumbers, kale, butterhead- and romaine lettuce. Samples were collected throughout the summer months when vegetables were locally produced and available. Analysis for mineral nutrition included nitrogen, phosphorous, potassium, calcium, magnesium, sulfur, iron, manganese, boron, copper and zinc. Brix analysis was used to determine levels of soluble solids and sugar content. Although the nutrient content varied among vegetables procured from stores, farmers markets or locally grown, the mineral levels within a particular crop were less variable. The highest amounts in percent of dry weight for nitrogen (5.0 ± 0.60), phosphorous (0.7 ± 0.27) and potassium (5.8 ± 1.75) were recorded for butterhead- and romaine lettuce. Iron content was also significantly higher with more than 200 ppm in the two types of lettuce. The analysis showed produce grown locally or obtained from the farmers market generally had greater Brix values to suggest higher sugar content than produce from local stores. The Brix value for locally grown red bell peppers for instance, was 8.7 ± 0.68 compared to 5.5 ± 0.36 for a similar store bought pepper. Three cultivars (Aroma 2, Dolly and Nufar) of the culinary herb basil grown in six light qualities were evaluated for mineral and sugar content. The treatments included blue LEDs (peak emission at 450 nm), red LEDs (50:50, peaks at 625 and 660 nm), blue/red LEDs (20:40:40, peaks at 450, 625 and 660 nm), and white LEDs (5000K). In addition, T5 fluorescent (4100 K) and natural greenhouse light supplemented with high-pressure sodium irradiance were used. Plants were grown at a constant 21 ± 2°C with a 16-hour photoperiod at a photosynthetic photon flux of approximately 150 µmol·m-2s-1. The plants were grown from seeding under the specific light qualities and the experiment was terminated after 50 days. Brix analysis was used to determine soluble solids and sugar content in recently mature leaves. There was a trend for higher Brix under blue LEDs among cultivars. The cultivar Aroma 2 had in general the greatest Brix values to suggest higher sugar content than in leaves of Dolly or Nufar. Brix values above 4.0 were consistently recorded for Aroma 2 except in the white LED environment. The blue/red environment supported growth and top dry weight well for Aroma 2 and Nufar. Least dry weight was observed for all cultivars under fluorescent irradiance. Dolly appeared to be less suitable for control environment production than Aroma 2 or Nufar based on dry weight accumulation. Soluble solids were also appreciably lower for Dolly with the exception of the blue LED environment. 1. Advance production and management techniques for Alaska agricultural production in greenhouses and controlled environment production facilities through novel technologies, methods and innovations. Several studies are in progress to determine the effects and potential implementations of LEDs for greenhouse and controlled environment production. Sustainable and efficient greenhouse systems to produce vegetables that are specifically suited to high latitudes are also evaluated 2. Develop sustainable greenhouse control methods to improve resource use efficiency, climate uniformity, production quality, productivity and yields. LEDs with expected higher energy efficiency and adjustable spectrum, suggest improved resource use while allowing for a more uniform growing environment to support crop productivity and quality. Greenhouse production systems taking advantage of the extended daylight hours in the summer and transitioning into less light demanding crops during the winter can be expected more resource efficient and sustainable in northern climates. 3. Disseminate information about controlled environment technologies, methods and approaches to producers throughout the state. As we gain knowledge and understanding of LEDs and other production techniques, we anticipate additional publications and outreach efforts in this area. 4. Teach up-to-date greenhouse, indoor farming and controlled environment technologies to beginners, producers, and students in formal educational programs. In the fall of 2018, the course Applied Plant Science was offered to undergraduate students. This course had a significant emphasis on the sustainable use of resources and the management of light and other climatic conditions. The courses Principles of Sustainable Agriculture and Greenhouse Management were offered in the spring of 2019. The college level greenhouse management course includes substantial information on modern control and management techniques for greenhouses and controlled environments. Understanding and implementing greenhouse and season extension environments are essential for efficient local northern crop production. 5. Publish research findings, prepare educational materials, and exchange information with stakeholders, extension personnel and researchers in the U.S. and internationally. Results and experiences on the efficient use of LEDs, protocols for greenhouse bell-pepper production and the nutritional value of locally grown produce have been communicated at state, national and international scientific conferences, as well as in post-secondary education and producer oriented gatherings. The annual ASHS (American society for horticultural science) meeting was in July of 2019. This conference provided extensive opportunities for information exchange and discussions relative to the use and adaptation of LED lighting technologies in research and crop production along with the use and implementation of controlled environment facilities for crop production in various geographic locations and climates.

Publications

• Type: Other Status: Published Year Published: 2019 Citation: Karlsson, M. 2019. Nutritional quality of Alaska grown produce. HortScience 54(9):S277.
• Type: Journal Articles Status: Accepted Year Published: 2020 Citation: Karlsson, M. 2020. Light quality affects growth and nutrient content in basil. Acta Horticulturae (in press).
• Type: Other Status: Published Year Published: 2018 Citation: Grandfield, M. and M. Karlsson. 2018. Sustained fruit load development in greenhouse bell peppers. HortScience 53(9):S385.