Effects of local CO₂ enrichment on strawberry cultivation during the winter season

In strawberry production, carbon dioxide (CO₂) enrichment is widely used to promote crop photosynthesis and to improve growth and yield of strawberry fruits. However, a standard CO₂ enrichment method has not been established clearly. For sustainable strawberry production with high profitability, it is essential to establish an efficient system for CO₂ enrichment. Therefore, in this study, we newly propose a local CO₂ enrichment system. The system enriches CO₂ only ambient to strawberry crops, not a whole greenhouse, and thereby enables efficient control of CO₂ concentration. We applied this system in a strawberry cultivation greenhouse with ventilating windows and examined the performance of system. During the daytime on clear days with opened greenhouse ventilation windows, the proposed system stabilized the ambient CO₂ concentration to strawberry crops at 800 ppm. Furthermore, when the day after CO₂ enrichment was begun, strawberry crop photosynthesis and photosynthate translocation from source leaves were promoted as the effects of short-term CO₂ enrichment. Nevertheless, the yields and quality of fruits was not affected by the system. It is considered that long-term CO₂ enrichment thickened source leaves and thereby caused down-regulation of photosynthesis. Further consideration will be needed on effect of long-term CO₂ enrichment on physiological function of crops.