Final report for GW24-001
Project Information
Severe climatic conditions, widespread urbanization, and demand for fresh local food have driven rapid growth of controlled environment agriculture (CEA). This technology-based approach has the potential for year-round, reliable, and local crop production. Optimizing production inputs (e.g., fertilizer, electric lighting) to enhance crop yield and quality provides an economic incentive for growers while also providing environmental benefits by reducing unnecessary natural resource use. However, a need exists for crop-specific production protocols in CEA to optimize significant production inputs, such as carbon dioxide (CO2). Additionally, while production protocols currently exist for many leafy greens, limited information is available for emerging, more nutritionally robust CEA crops, such as strawberry. The goal of the proposed research is to evaluate the impact of CO2 enrichment on strawberry yield and quality to better understand the extent to which this input is beneficial for indoor production. Our project will integrate high resolution photosynthesis data with novel phytochemical profiling to elucidate how strawberry utilizes CO2 during the reproductive growth phase and the impacts on fruit number, size, marketability, and ultimately, profitability. We plan to creatively influence wider adoption of CEA strawberry production through community-driven science, specifically, sensory analysis with local Denver residents. Increasing opportunities for the community to participate in agriculture has social implications. Addressing inequities surrounding secure, reliable, and fresh food access will enhance quality of life and human health in Denver and beyond. The outcomes of the project will be cultivar-specific, everbearing strawberry CO2 enrichment protocols for CEA production, which will be shared broadly with existing and aspiring growers nationally at conferences, regionally at western agricultural producer gatherings, and locally through educational outreach events organized at the Colorado State University (CSU) Spur campus. Our research will ultimately contribute to both economically viable crop diversification in CEA and improved sustainability through increased resource use efficiency.
Research Objectives
The overall objective of this research is to develop and disseminate specific CO2 protocols for controlled environment production of everbearing strawberries that will enhance yield and fruit quality. We will grow two cultivars of strawberry under ambient and enriched CO2 concentrations during the reproductive growth stage to achieve the following sub-objectives:
- Compare the morphological and physiological responses throughout the reproductive growth stage for plants grown under ambient and enriched CO2 concentrations.
- Quantify the impact of enriched CO2 concentrations on fruit yield and morphology.
- Evaluate the impact of an enriched CO2 concentration on fruit quality attributes.
Educational Objectives
The objective of the educational component of this research is to coordinate and lead educational activities that promote interest and engagement in controlled environment strawberry production in Denver, Colorado. We will achieve this using the following sub-objectives:
- Provide CO2 enrichment guidelines for CEA strawberry production to existing and aspiring producers.
- Promote interest and engagement in CEA strawberry production and expansion in Denver.
Cooperators
- - Producer
Research
Plant Production
Two cultivars of everbearing strawberry (Fragaria × ananassa ‘Albion’ and ‘Ozark Beauty’) were evaluated. Bareroot strawberries (experimental runs 1 and 2) or aeroponically propagated vegetative runners (experimental runs 3 and 4) were planted in 1-gallon containers containing a soilless substrate comprised of perlite (50%) and a peat-based substrate (50%; Promix HP + Biofungicide/Mycorrhizae High Porosity). Plants were grown in a walk-in growth chamber (GR64; Conviron, Temecula, CA) set to maintain 22/18 °C day/night air temperature, 55/65% day/night relative humidity (RH), and 450 µmol∙mol–1 CO2 for approximately eight weeks. An 18-h photoperiod (0500 to 2100 HR) with a target photosynthetic photon flux density (PPFD) of 348 µmol∙m–2∙s–1 [daily light integral (DLI) ≈ 21 mol∙m–2∙d–1] was provided with light-emitting diode (LED) fixtures (Ray 44 Physiospec Indoor; Fluence, Austin, TX). Finally, drip irrigation delivered a water-soluble fertilizer providing 100 mg∙L–1 N (Jack’s 8-10-26 K Strawberry Part A and Jack’s 15-0-0 Calcium Nitrate Part B; J. R. Peter’s Inc., Allentown, PA) once per day. Nutrient solution electrical conductivity (EC) was maintained no higher than 1.0 dS∙m–1 with a pH target of 5.5-6.5. Flowers were removed during this time to ensure vegetative growth was prioritized.
After eight weeks, flower removal ceased and ten plants per cultivar were randomly assigned to four walk-in growth chambers (GR64), with two chambers set to an ambient CO2 concentration (450 µmol∙mol–1) and the others set to an enriched CO2 concentration (900 µmol∙mol–1). Other environmental parameters matched those described above, except temperature, which was adjusted to 20/12 °C (day/night) in both chambers. Additionally, as the plants developed, a second and third daily irrigation event was added. Plants were hand-pollinated using a soft-bristled brush to ensure complete pollination, and new runners were removed to ensure resources were diverted to fruit development. Fifteen minute averages of air temperature, RH, and CO2 concentration for each chamber were logged using an air temperature and RH probe (EE08-SS; Apogee Instruments, Inc., Logan, UT) and CO2 probe (GMP252; Vaisala, Woburn, MA) and were collected with a datalogger (CR1000X; Campbell Scientific, Inc., Logan, UT).
Data Collection
Subobjective 1
By comparing photosynthetic responses of two everbearing strawberry cultivars, we can elucidate early signs of acclimation to elevated CO2 conditions within the first week of production, allowing for a clear understanding of when photosynthesis may begin to decline under these conditions and, ultimately, what timing and duration of CO2 enrichment may be most beneficial.
Survey gas exchange measurements were collected every day for seven days on two plants per cultivar, per CO2 treatment, per experimental run (n=8). The same leaf on each plant was measured using a portable photosynthesis meter (LI-6800; LI-COR Inc., Lincoln, NE) fitted with a 2 cm2 leaf cuvette. Cuvette conditions matched chamber conditions (20 °C, 55% RH, and 348 µmol∙m–2∙s–1 PPFD), with reference CO2 concentration based on treatment. On day 1, three sets of survey measurements were taken on one recently fully expanded leaf: 1) all plants in both treatments were measured at 400 µmol∙mol–1 (ambient) CO2 to establish baseline photosynthesis, 2) plants assigned to the enriched (900 µmol∙mol–1) treatment were surveyed again at a CO2 concentration of 900 µmol∙mol–1 to ascertain the initial response to CO2 enrichment, and 3) plants assigned to the enriched treatment were surveyed at enriched CO2 and saturating light intensity (1500 µmol∙m–2∙s–1) to determine maximum photosynthetic potential when light limitations are removed. This procedure was repeated on subsequent days on the same leaf, except plants assigned to the enriched treatment were not surveyed again at an ambient CO2 concentration.
On days 7 and 8, rate of photosynthesis (A) in response to increasing internal leaf CO2 concentration (A-Ci curves) was collected on all of the tagged leaves. Cuvette conditions matched chamber conditions (20 °C and 55% RH), but with a saturating light intensity (1500 µmol∙m–2∙s–1 PPFD). For plants grown under ambient CO2 concentration, measurements began at 400 µmol∙mol–1 CO2, decreased to 50 µmol∙mol–1, returned to 400 µmol∙mol–1, and finally increased to a maximum of 1000 µmol∙mol–1 in 100 µmol·mol-1 increments to prevent feedback inhibition. For plants grown under the enriched CO2 concentration, measurements began at 1000 µmol∙mol–1 CO2 and decreased to 50 µmol∙mol–1 in increments of 100 µmol·mol-1.
The Farquhar–von Caemmerer–Berry model was fit to A-Ci curves, as described by Dubois et al. (2007) to estimate maximum rate of rubisco carboxylation (Vcmax) and rate of electron transport (Jmax). Vcmax is correlated to photosynthetic efficiency (Rubisco), so if enriched plants show a decline in Vcmax, we can conclude that they are using CO2 less efficiently and acclimation has occurred.
On day 58, all plants that were used for gas exchange were destructively harvested for biomass data. Leaf number, leaf area, relative chlorophyll content, crown number, and crown diameter were measured. Plants were separated into unripe fruit, flower/bud, truss, leaf, stem/petiole, and crowns, then dry masses weighed. Leaf mass area (LMA) was calculated by dividing total leaf dry mass by leaf area (g∙cm–2). This destructive data complemented the gas exchange data by providing insight on whether CO2 acclimation may also be facilitated by changes in plant morphology. In our previous research focused on vegetative growth, we found significantly thicker leaves (greater LMA) in enriched treatments for petunia and strawberry, which was indicative of an acclimation response. However, no differences in total dry mass were observed between the ambient and enriched CO2 concentrations for these species, thus limiting the benefits of CO2 enrichment for biomass accumulation.
Subobjective 2
Yield data was assessed for all plants grown in the above experiment. Flower and fruit number per truss was counted at treatment initiation. Days to first fruit harvest was recorded for all plants. All strawberries that were at least 95% red were harvested and counted from all plants on days 23, 30, 37, and 44. Additionally, all harvested berries from each treatment were weighed and marketability assessed using the USDA fruit grade rating scale. On day 44, firmness of all harvested berries were tested with a fruit compression tester (FirmTech; BioWorks, Inc, Cleveland, OH), and sugar and acid content assessed on a pooled sample using a digital refractometer (PAL-BX|ACID4; Atago, Bellevue, WA).
Subobjective 3
Attributes of fruit quality elucidated whether there are value-added benefits with CO2 enrichment. Empirical measures of sweetness and sourness coincided with sensory assessments of the same attributes for a more holistic picture of desirable strawberry characteristics. Nutritional profiling of strawberry fruits evaluating a variety of plant metabolites, such as phytochemicals, further reveals potential impacts of CO2 enrichment for human health.
Eighty four fruits from each cultivar and treatment, not used for the fruit quality testing in Subobjective 2, were washed and stored in a food-safe cooler prior to the sensory test. Participants were recruited from the Denver Metro area through the Sensory Testing Lab distribution list. Paperwork was submitted to the CSU Institutional Review Board (IRB) for review and approval before the start of the study, and panelists, who were at least 18 years old, gave written, informed consent prior to participating. Panelists were not financially compensated for participation but were provided non-financial incentives from the Sensory Testing Lab with non-grant funds. All sensory analysis took place in good standard sensory evaluation conditions (Lawless and Heymann 2010). The sensory tests took place at the Sensory Testing Lab at Spur, under the supervision of Dr. Martha Calvert, the Sensory Lab Manager. Participants were asked to answer demographic information after taking the test. Each panelist was served a whole berry from each CO2 concentration and cultivar (four samples total) in individual booths, with serving order randomized between participants and participants blinded to the treatment. For each sample, participants were asked to rate the intensity of aroma, flavor, and texture attributes from a list using a 10-point structured scale anchored by “not present” and “very strong”. Lastly, participants assessed overall liking using a 9-point hedonic scale anchored by “disliked extremely” and “liked extremely”. Participants were provided with crackers and water for palette cleansers between samples. Data were analyzed using standard multivariate procedures including analysis of variance (ANOVA) and principal component analysis (PCA) to determine drivers of liking for strawberry sensory quality.
A representative sample of fruits from each cultivar and treatment weighing a combined total of at least 70 grams (fresh weight), were collected, frozen in dry ice, then stored in –80 °C until extractions. Standardized high-throughput omics platforms developed as part of the Periodic Table of Food Initiative (PTFI) were utilized to characterize the nutrient composition. Specifically, metabolite analysis was performed using ultra-performance liquid chromatography mass spectrometry (UPLC-MS) followed by data analysis using an open-source cloud-based PTFI pipeline. Metabolite annotation was based on queries against the PTFI reference standard library. All results from this analysis will be shared in the publicly accessible PTFI food composition database, which will increase the impact of these results beyond the current study. This objective was achievable with the assistance of Dr. Jessica Prenni, Professor in the Department of HLA at CSU and CSU Bioanalysis and Omics Core Facility.
Data Analysis
The experiment was run four times, with assigned CO2 treatments in chambers switched between runs to account for chamber effects. A randomized complete block design was used with the replication in time serving as the block. Each plant was considered the experimental unit. An ANOVA was conducted using the PROC MIXED procedure in SAS OnDemand for Academics (SAS version 9.4), followed by pairwise comparisons for variables that had a significant F-test (P-value <0.05). Fixed effects in the model were the two levels of CO2, while the random effect was run.
Citations
Dubois J-JB, Fiscus EL, Booker FL, Flowers MD, Reid CD. 2007. Optimizing the statistical estimation of the parameters of the Farquhar–von Caemmerer–Berry model of photosynthesis. New Phytologist. 176(2):402–414. https://doi.org/10.1111/j.1469-8137.2007.02182.x.
Lawless HT, Heymann H. 2010. Sensory evaluation of food: Principles and practices. Springer, New York, NY, USA. https://doi.org/10.1007/978-1-4419-6488-5.
Table 1. Timeline tasks and dates completed for objective 1.
| Objective 1: Develop and disseminate specific CO2 protocols for controlled environment production of everbearing strawberries that will enhance yield and fruit quality. | |
| Activity | Completed |
| Secure project supplies and materials | June 7, 2024 |
| Establish and monitor growth chamber environmental controls | May 15, 2024 |
| Hire undergraduate assistant | June 5, 2024 |
| Establishing strawberry plants in chambers | June 12, 2024 |
| Experiment initiation, plants in treatments | June 26, 2024 |
| Gas exchange data collection | July 26, 2024 |
| Destructive harvest data collection (milestone) | August 24, 2024 |
| Data analysis and project assessment | January 22, 2025 |
Subobjective 1
Daily survey measurements showed that CO2 enriched plants in both cultivars maintained consistently higher Anet compared to ambient throughout the 7 days of survey (Figures 1 and 2). Anet of enriched 'Ozark Beauty' declined starting on day 2 compared to the ambient CO2 concentration, which remained relatively stable throughout the collection period (Figure 2). Thus, the benefit to Anet from CO2 enrichment was not sustained for 'Ozark Beauty' throughout the first week of production, indicating a cultivar-specific response to CO2 concentration.
Figure 1 (left) and Figure 2 (right). Daily net photosynthesis (Anet) of strawberry (Fragaria × ananassa) 'Albion' (left) and ‘Ozark Beauty’ (right) leaves grown under an ambient (450 µmol∙mol–1; open circles) or enriched (900 µmol∙mol–1; filled circles) CO2 concentration for 7 d. Means sharing a letter within each CO2 concentration (denoted by upper and lowercase letters) are not statistically different according to Tukey’s honestly significant difference test at P ≤ 0.05. Asterisks indicate significant differences according to Tukey’s honest significant difference test at P ≤ 0.05 between CO2 treatments on a given day.
Gas exchange measurements revealed evidence of photosynthetic acclimation on day 7 for both cultivars, indicated by a decrease in Vcmax under the elevated CO2 treatment (Figures 3 and 4). Similarly, Jmax declined in tandem with Vcmax for both cultivars (data not shown). Jmax of 'Albion' produced under ambient conditions was 169.5 μmol∙m–2∙s–1 compared to 140.7 μmol∙m–2∙s–1 under the enriched CO2 concentration, while Jmax for 'Ozark Beauty' produced under ambient conditions was 127.8 μmol∙m–2∙s–1 compared to 101.7 μmol∙m–2∙s–1 under the enriched CO2 concentration. Thus, signs of photosynthetic acclimation resulting from an increased CO2 concentration appear to be evident within the first week of CO2 enrichment.
Figures 3 (left) and 4 (right). Vcmax comparison of strawberry (Fragaria × ananassa) 'Albion' (left) and ‘Ozark Beauty’ (right) leaves grown under an ambient (450 µmol∙mol–1) or enriched (900 µmol∙mol–1) CO2 concentration for 7 d.
Subobjective 2
Total yield (grams/plant) of both cultivars was highest under CO2 enrichment with a 22% and 36% increase in 'Albion' and 'Ozark Beauty', respectively (Table 2). Average fruit number was greater under the enriched CO2 concentration for 'Ozark Beauty', while there was no difference detected between CO2 treatments for 'Albion'. Thus, the sustained increase in Anet observed under the enriched compared to ambient CO2 concentration for both cultivars appears to have led to an increase in strawberry yield. Although signs of photosynthetic acclimation (decreased Vcmax) were observed under the enriched CO2 concentration for both cultivars, this decrease did not appear to impact the benefit of CO2 enrichment on strawberry yield. There was no difference detected between CO2 treatments for average fruit width in 'Ozark Beauty', while widths were greater under the enriched CO2 concentration for 'Albion' compared to ambient. Quality differences (firmness, brix, and acid) were not significant between CO2 treatments and mainly occurred between cultivars. Thus, fruit quality responses are likely species-specific and depend on other external factors.
Table 2. Fruit number, yield, fruit width, firmness, Brix, and acid content for strawberry (Fragaria × ananassa) 'Albion' and 'Ozark Beauty' grown under an ambient (450 μmol∙mol-1) or enriched (900 μmol∙mol-1) CO2 concentration. Fruit were collected weekly and data were measured at each harvest (yield and width) or 8 weeks after treatment initiation (firmness, Brix, and acid).
| Fruit Number | Yield (g/plant) |
Fruit Width (cm) |
Firmness (N∙m–2) | Brix | Acid Content | |
| Albion | ||||||
| Ambient | 8.8 | 155.7 b | 3.2 b | 212.0 | 9.0 | 1.7 |
| Enriched | 9.0 | 190.0 a | 3.4 a | 205.1 | 8.9 | 1.7 |
| Ozark Beauty | ||||||
| Ambient | 11.2 bi | 75.4 b | 0.9 | 164.1 | 12.6 | 1.7 |
| Enriched | 14.4 a | 102.3 a | 0.9 | 167.4 | 14.4 | 1.8 |
iMeans sharing a letter within cultivar are not statistically different according to Tukey’s honestly significant difference test at p ≤ 0.05 while means without letters are not significant within cultivar.
Subobjective 3
Fruit quality results were similar to sensory evaluations for rate-all-that-apply (RATA) and affective (9-point hedonic scale) tests (n=84). Participants rated ‘Albion’ significantly higher in overall appearance and overall liking compared to ‘Ozark Beauty’, regardless of CO2 treatment (data not shown). CO2 treatment did not have a significant impact on any sensory attribute (Figure 5). When comparing cultivars, ‘Ozark Beauty’ consistently and significantly rated higher in fermented flavor compared to 'Albion', while there were no differences in average ratings for any other sensory attributes. Caramel flavor did not appear to be an applicable term for either cultivar given the low ratings for all samples.
Figure 5. Average participant rating for attributes of strawberry (Fragaria × ananassa) 'Albion' and 'Ozark Beauty’ grown under ambient (450 μmol∙mol-1) or enriched (900 μmol∙mol-1) CO2 concentration (n=84). An asterisk indicates that means of that attribute are statistically different according to Tukey’s honestly significant difference test at P ≤ 0.05.
Similar to the sensory evaluation, most of the differences in nutrient composition observed were between cultivars (Figure 6). Specifically, "PC1" in Figure 6 references cultivar, with 22.3% of the variation observed in the analysis attributed to differences between 'Albion' and 'Ozark Beauty', regardless of CO2 treatment. Additionally, more total variation in nutrient composition was observed for the cultivar 'Ozark Beauty' compared to 'Albion', which is expected given that 'Ozark Beauty' is not a common greenhouse cultivar having been bred in the United States for adaptability to northern climates as well as high elevations in the south (Figure 6). Few differences in nutrient composition from CO2 treatment were observed, indicating CO2 enrichment has little effect on the final phytochemical profile of strawberry fruit.
Figure 6. Principal component analysis (PCA) plot evaluating over 2,000 variables related to nutrient composition for strawberry (Fragaria × ananassa) 'Albion' and 'Ozark Beauty’ fruits grown under ambient (450 μmol∙mol-1) or enriched (900 μmol∙mol-1) CO2 concentration.
Research outcomes
Project Research Outcomes:
CO2 enrichment increased everbearing strawberry fruit production without negatively impacting berry flavor or nutritional content of these two cultivars. Based on the improvement in fruit yield of both cultivars ('Albion' and 'Ozark Beauty'), our recommendation for growers interested in the production of everbearing strawberries in controlled environments is to enrich the production space with a CO2 concentration of 900 µmol·mol–1. Given that 'Albion' outperformed 'Ozark Beauty' in most metrics, producers should consider more robust commercial cultivars such as 'Albion'. This recommendation for CO2 enrichment along with other critical production information for strawberries in controlled environments has been distributed via our "Indoor Strawberries Grower's Guide."
These results were presented at the annual ProGreen Expo in Denver, which attracts more than 5,000 greenindustry professionals. In graduate student applicant Rosado’s presentation in 2023, the audience included both CEA and field producers. The Expo took place January 28-30, 2025, and a presentation was given that highlighted the parameters and benefits of CO2 enrichment. Educating on the different methods available to provide enrichment and basic growth conditions for strawberries will also be important, particularly for new growers or growers that do not currently enrich with CO2 in their operations. A QR code at the end of the presentation circulated a digital copy of the CO2 protocols, and paper copies were also furnished, both with graduate student applicant Rosado’s contact information. A version of this presentation was also given and recorded at the CSU Horticulture and Landscape Architecture Department Seminar on February 18, 2025, which was open to the entire CSU community, with most representation from department faculty and graduate students. Undergraduate research assistant on this project, Yamilex Romero, also presented this research at the 2025 CSU Multicultural Undergraduate Research and Leadership Symposium. Lastly, these results were also shared at the 2025 American Society for Horticultural Science (ASHS) Annual Conferencein New Orleans, LA. Two abstract citations from research presented at this conference are included below:
Craver JK, Rosado SP, Boldt J, Harbick K. 2025. Short-term carbon dioxide enrichment results in physiological acclimation within one week for strawberry. HortScience. 60:S321-S322.
Romero Y, Rosado SP, Boldt J, Harbick K, Calvert M, Sanchez G, Holley J, Craver JK. 2025. Carbon dioxide enrichment increases yield without negatively affecting fruit quality of everbearing strawberries produce. HortScience. 60:S188.
The recommendations we have provided for the production of strawberries in controlled environments should improve resource use efficiency and reduce unnecessary production inputs. While not characterized by our research, CO2 enrichment has been shown to improve water use efficiency as well as light use efficiency, leading to further reductions in input use for controlled environment production. Importantly, CO2 enrichment up to 900 µmol·mol–1 has been shown to improve strawberry yield with currently no impact on fruit quality, sensory attributes, or nutritional content.
Project Educational Outcomes:
Results of the Western SARE survey or other evaluation tool reporting on the impact of the project on participants are included. The Western SARE survey tool garnered a total of 61 responses between all the educational outreach events (with the exception of the Semilla Project, which had its own built in survey tool). Feedback from this survey follows:
- The educational activity improved my awareness of topics covered and the educational activity provided new knowledge (all 61 answered yes).
- The educational activity provided new skills (43 yes, 11 no, 6 na).
- The educational activity modified my opinions and/or attitudes (44 yes, 13 no, 3 na).
- How many people do you estimate you will share some aspect of this project within the next 12 months (728, with some respondents indicating a lot, many, or unknown).
Education and Outreach
Participation summary:
Subobjective 1
Protocols regarding the timing and concentration of CO2 enrichment were created for CEA production of strawberry ‘Albion’ and ‘Ozark Beauty’. For existing growers, these outlined the benefits expected based on our research and may serve as decision-support tools for investing in or modifying CO2 regimes in their operation. Aspirant new growers can expect to receive research-based information that will help guide their entry into the market as well as considerations for diversifying their crop portfolio. Protocols reached producers and agricultural professionals in several ways.
The National Western Stockshow is a historical, annual event at the National Western Stock Center in Denver. It attracts thousands of attendees from across Colorado and Wyoming, and it is advantageously located right next to the CSU Spur campus. As a reference, there were 700,000 attendees for the 2023 National Western Stock Show with ~15,000 recorded visitors to the CSU Spur Terra building (Terra focuses on Food and Agriculture) during the event. The Stockshow during this project was January 11-26, 2025. Graduate student applicant Rosado and undergraduate assistant Romero disseminated project results to both agricultural producers and consumers by hosting tours in the CEA Lab, located in the Terra building, on three show days (Table 3) that coincided with Spur’s operating hours. Informational materials were available outside the lab for visitors to take throughout Stockshow, and graduate student applicant Rosado and undergraduate student Romero were present to communicate with visitors about CEA strawberry production.
Further, a CSU Source article (included in the list of products below) was published in September 2025 which highlighted this project. The project was also highlighted via the CSU Spur campus Instagram: https://www.instagram.com/p/DOcBAVBFcPw/.
Subobjective 2
Activities that reduce barriers to entry by facilitating the transfer of technology and knowledge of CEA strawberry production were coordinated. This open access to education will directly involve the Denver community and establish trust by accounting for the needs and livelihoods of the people the research directly intends to affect. Additionally, positioning residents as active participants in agriculture and science will contribute to wider adoption of CEA strawberry production in the city and reduce harm in marginalized communities by addressing historic disparities. Conducting the research at the CSU Spur campus leveraged existing, built-in educational outreach mechanisms. The sensory analysis used to assess fruit quality and consumer acceptability will also serve to creatively influence wider adoption of CEA strawberry production through community-driven science. The tests were conducted at the CSU Spur Sensory Testing Lab on January 2025 (Table 3). Prioritizing participation from residents in Globeville and Elyria-Swansea, two surrounding neighborhoods, is realistic and relevant given Spur’s commitment to serving them in its institutional framework and existing network of connections through the Office of the Denver Program Manager. Given the high poverty incidence and predominant Black and Latinx ethnic makeup in these underserved communities, materials were translated into Spanish by bilingual undergraduate assistant Yamilex Romero.
Spur Second Saturdays are free and open to the general public, featuring extra campus programming to engage visitors in hands-on experiences that are not normally available during weekly hours. Planned dates, which overlapped with the experiment duration were May 11, June 8, July 13, and August 10, 2024 (Table 3). Graduate student applicant Sam Rosado and undergraduate assistant Yamilex Romero invited visitors to tour inside the CEA Lab, where they were able to see inside the growth chambers from a viewing window, learned about strawberry pollination, and different ways to measure strawberry quality. Additionally, since the CSU Spur campus is open Monday-Friday from 9am-5pm, graduate student applicant Sam Rosado opened the CEA Lab for drop-in tours during daily operations during the data collection period (May-July 2024). The goal was to spur visitors’ excitement about the prospect of growing food locally in Denver. Graduate student applicant Sam Rosado and undergraduate assistant Yamilex Romero created a repository of questions and topics commonly discussed during tours and systematically coded for common themes related to interest to track this objective.
The Semilla Project, a five-year grant funded initiative to bring Denver Public Schools students to Spur, is an opportunity to engage underrepresented students (first generation, multicultural, limited income). These students experience what it can look like to be in agriculture and in a STEM field as they consider a future college career. In Spring 2023, the project served 16 high schools and 540 students. During this time, graduate student applicant Sam Rosado created and executed a workshop for two of the schools involving hydroponic lettuce production, data collection, and interpretation (Figure 2). Some of the students came from rural communities and agricultural families, while some had no previous connection to agriculture. This is a unique opportunity to build up existing interest and bring in new community members to help agriculture continue to thrive and promote sustainable practices in Colorado. The Semilla Project was scheduled for Fall 2024 and Spring 2025 (Table 3). At four of the visits, graduate student applicant Sam Rosado and undergraduate assistant Yamilex Romero provided students with an engaging research activity, where they learned about strawberry production, and then collected data on strawberries produced conventionally and organically, followed by a sensory analysis. In this way, students got to experience science and CEA, and ask questions that are important to them and the communities they care about. The Semilla Project has a built-in survey administered after the visit to assess the impact of all elements of the event, so this was be used to measure student interest in CEA strawberry production.
Table 3. Timeline tasks and dates completed for objective 2.
| Objective 2: Coordinate and lead educational activities that promote interest and engagement in controlled environment strawberry production in Denver. | |
| Activity | Completed |
| Tours in the Controlled Environment Lab | May 11, 2024 |
| Second Saturday Activities | May 11, 2024 |
| Second Saturday Activities | June 8, 2024 |
| Tours in the Controlled Environment Lab | June 12, 2024 |
| Tours in the Controlled Environment Lab | June 26, 2024 |
| Tours in the Controlled Environment Lab | July 10, 2024 |
| Second Saturday Activities | July 13, 2024 |
| Second Saturday Activities | August 10, 2024 |
| Semilla Project activities | September 25, 2024 |
| Semilla Project activities | October 9, 2024 |
| Create general public educational materials | October 16, 2024 |
| Semilla Project activities | November 12, 2024 |
| Create general public educational materials | January 9, 2025 |
| National Western Stockshow | January 11, 2025 |
| National Western Stockshow | January 12, 2025 |
| National Western Stockshow | January 15, 2025 |
| Sensory Analysis Panels (milestone) | January 21, 2025 |
| ProGreen Expo presentation | January 29, 2025 |
| Generate CO2 protocols for growers (milestone) | January 30, 2025 |
| CSU Horticulture Department Seminar | February 18, 2025 |
| Semilla Project activities | March 12, 2025 |
Subobjective 1
Holding the sensory trial during National Western Stockshow was an effective way to recruit participants that would already be at Spur. Delivering the CEA lab tours in both English and Spanish was also effective in making meaningful connections with community members, specifically for Denver Public Schools that brought groups of students.
ProGreen Expo had attendees from the horticulture industry, but it was unclear how many completed the WSARE survey tool. Expanding our outreach efforts to other industry conferences, such as the Annual Colorado Fruit and Vegetable Growers Association (CFVGA) Conference, may improve CEA producer adoption of the CO2 enrichment protocols developed as a result of this research.
Subobjective 2
Perceptions questions following the sensory test showed that 81% of participants had a desire to grow their own food, suggesting interest in local food production in Denver. Only 5 of the 84 sensory trial participants reported living in the Elyria Swansea or Globeville zipcode. One explanation could be that our primary communication channel through e-mail may not have been an effective modality of communication and/or the sensory lab e-mail distribution list does not include a large population of this community. To reach these communities, visiting areas of community gathering and networking with trusted organizations that already serve the community may have been more effective in our recruitment efforts. Additionally, offering the sensory trials at a place of community gathering or during an evening or on a weekend may have been more conducive to broadening access for this population of participants.
Giving tours in the CEA lab during data collection days was not effective as it delayed data collection. Time of collection impacts gas exchange measurements, so one change might have been to prepare an informational video explaining the gas exchange measurements. Then visitors could observe those measurements being taken in real time from the window.
Thematic coding of visitor questions asked during Second Saturday and National Western Stockshow educational outreach activities revealed 10 distinct topics of questions with one "other" category (Figure 7). The largest percentage of questions fell into "Experiment specific/Research/Instrumentation." For example, one visitor asked "What is the application of this research to outdoor growers?" The nature of many questions in this category suggested that visitors were interested in methodology and rationale, specifically, how research is created and who it serves. This may signal that community members already have ideas about research questions that are important to them to pursue. Surprisingly, only 10% of questions were coded as interest in "Strawberry growth/lifecycle/industry."
Figure 7. Distribution of question topics asked during Second Saturdays and Stockshow educational outreach activities.
Observations of student engagement during Semilla Project activities indicated that students were satisfied with their educational experience. For example, during one visit, students were assigned to the strawberry activity or the music activity. At first, students assigned to the science-based strawberry activity appeared disappointed. At the end of the activity, a student said they had a lot more fun than they expected to. When reviewing the results of their data collection for the activity, students were attentive, surprised about their findings, and one even shared that they would be letting their grandparents know what we they learned about the strawberries they evaluated.