Abstract
This study was carried out to develop a labor-saving system for hydroponic culture of spinach to avoid the injury associated with continuous cropping. This culture system consists of a seedling bed and a hydroponic culture bed. The seedling bed is simple in structure. Two styrofoam blocks are put together, and a sheet of cloth is inserted into a slit between the blocks. Raising of spinach seedlings is difficult, because germination requires an accurate moisture control, and the primary root shows a weak penetration ability into substrates. In the seedling bed, the cloth is maintained constantly under suitable moisture conditions around the seeds, and there are no obstacles to the growth of the primary root. As a result, a high production of spinach seedlings was achieved by using the seedling bed. The germination percentage (8 days after sowing) was 73%, and the percentage of establishment of the seedlings was 71%. The hydroponic culture bed is placed on a high floor, and it has a heat exchanger to control the root zone temperature. This culture system is highly efficient. All the operations for transplanting to culture bed require the setting of the seedling bed in the panel on the culture bed, and for harvesting the seedling bed can be pulled out. Furthermore, by fitting the size of the seedling bed to the unit of a bundle spinach, packing can be performed rapidly for shipping.
