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.
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