Twofold increase in strawberry productivity by integration of environmental control and movable beds in a large-scale greenhouse

The effect of combinational environment control, incorporating supplemental lighting and elevated CO₂ concentration (maintained at 1,000 mu;mol mol^-1) and air temperature (T_A; maintained between 15 and 27°C in the day), on growth and fruit yield of June-bearing strawberry 'Benihoppe' was examined under forcing culture. Supplemental lighting significantly enhanced leaf photosynthesis, and this response was further increased by elevated CO₂ and T_A treatment. Flower opening on the first and second inflorescences was accelerated by supplemental lighting, and was further accelerated by elevated CO₂ and T_A, and resulted in a significant increase in fruit yield. Flower number per inflorescence was significantly increased under supplemental lighting and/or elevated CO₂ and T_A. Increase in flower number and shortening of the fruit maturation period caused by increasing the average air temperature under elevated CO₂ and TA resulted in a significant increase in harvested fruit number and yield. By integration of combinational environment control and 1.5-fold increase in planting density (from 8 to 12 plants m^-2) with a movable bed system, the fruit yield per unit land area achieved was 10.7 kg m^-2 (10.7 t / 10 a), which represented a more than two-fold increase in yield compared with that attained in a conventional stationary bed system.