ASHS 2025 Conference

Strawberries are the top consumed and produced berry in the United States. Demand for local and off-season availability has increased the production of strawberries in controlled environment agriculture (CEA). While production protocols exist for many leafy greens, limited information is available for emerging CEA crops such as strawberry. Optimizing carbon dioxide (CO2) concentrations for CEA strawberry production is of interest, given that previous research has shown increased yields and enhanced organoleptic properties of strawberries with CO2 enrichment. However, strawberry chemical composition varies depending on cultural practices, environmental conditions, and cultivar. Therefore, the objective of this research was to evaluate the impacts of CO2 enrichment on yield and fruit quality of everbearing strawberries in a controlled environment. Two strawberry cultivars (Fragaria ×ananassa ‘Albion’ and ‘Ozark Beauty’) were propagated from vegetative runners and grown in 2.7-L pots for eight weeks in walk-in growth chambers under either an ambient (450 μmol·mol–1) or enriched (900 μmol·mol–1) CO2 concentration. Temperature and relative humidity setpoints were 20/12 °C and 55/65% (day/night), respectively, with a photosynthetic photon flux density target of 348 µmol∙m–2∙s–1 (18-h photoperiod; daily light integral of 21 mol∙m–2∙d–1). Fruit mass, width, and count were collected weekly on all ripe berries and a USDA grade was assigned based on width and presence of damage. During the final harvest, fruit firmness and Brix:acid were measured to further assess fruit quality and samples were collected for a sensory evaluation. Total yield (grams/plant) of both cultivars was highest under CO2 enrichment. Specifically, total yield increased by 22% and 37% under CO2 enrichment compared to ambient for ‘Albion’ and ‘Ozark Beauty’, respectively. No quality differences (e.g., fruit firmness and Brix:acid) were observed between CO2 concentration treatments for either cultivar. These results were similar to sensory evaluations for rate-all-that-apply (RATA) and affective (9-point hedonic scale) tests (n=84), with little difference observed between CO2 concentration treatments for either cultivar. Participants rated ‘Albion’ higher in overall appearance and overall liking compared to ‘Ozark Beauty’, regardless of CO2 treatment. ‘Ozark Beauty’ consistently rated higher in fermented flavor. In summary, CO2 enrichment increased everbearing strawberry fruit production without negatively impacting berry flavor for these two cultivars. Outreach efforts have sought to disseminate these results and, through program evaluation, identify interest and potential barriers to crop diversification and adoption of CEA strawberry production in Denver, CO.