Crop-local CO₂ enrichment improves strawberry yield and fuel use efficiency in protected cultivations

In protected strawberry (Fragaria × ananassa Duch.) cultivation, CO₂ enrichment is essential to enhance both fruit quality and yield. Fuel burning generators are commonly used to supply CO₂ to entire commercial greenhouse space. However, methods that are less fuel-based are desired for contemporary agricultural practices. A new crop-local CO₂ enrichment system using a modified fuel-burning generator has been developed to increase yields and decrease the fuel required for CO₂ enrichment in greenhouse strawberry production. This crop-local CO₂ enrichment (CLC) method directly supplies CO₂ from perforated tubes set in the interrow space of the plant canopy. The effects of this technique on fruit quality, fruit yield, and fuel use efficiency have been examined in comparison with conventional CO₂ enrichment (CC) practices. The CLC method increased CO₂ concentration inside the plant canopy by 100–200 μmol mol^–1 when compared with CC under the ventilating conditions by a roof window. This resulted in significant increases of approximately 10–26% in the average fruit weight, 13% in the cumulative fruit number, and 22% in cumulative marketable yield when compared to CC. Furthermore, cumulative fuel consumption was approximately 27% lower with the CLC method when compared to CC. These results indicate that CLC improves fuel use efficiency when compared with CC as it increased yields and decreased fuel consumption.