Abstract
Aiming at high yield and labor saving production of strawberry, an innovative cultivation system was newly developed by the three dimensional use of the greenhouse space. In this system, a double-seesaw mechanism vertically moves four beds, and the beds can be held at any desired height. Three dimensional use of the greenhouse space creates four times planting density as high as the conventional bench culture. Beds were moved among four heights of 2.8, 2.1, 1.4, and 0.7 m every two hours, but yield increased only 27% over conventional bench culture to a significant decline in integrated solar radiation on individual beds caused by shading. Fixing the beds in a two-height formation (2.1 and 0.7 m) increased integrated solar radiation on beds relative to the moving four-height formation and increased yield twofold. However, photosynthesis of lower-bed plants was only 50% of those on upper beds due to shading by upper beds. By exchanging the upper and lower beds at 11:00 and 14:00, photosynthesis on the beds in the two-height formation was equalized. Consequently, integrated photosynthesis across the moving beds in the two-height formation was 24% higher than on the beds fixed in that formation. Thus, by optimizing the vertical motion of beds based on leaf photosynthesis, the newly-developed system can achieve high yields of high-quality strawberries.
