| 摘要 |
PROBLEM TO BE SOLVED: To provide a bottom plate which does not let turfs die even when set on the turfs, has sufficient strength, and is simple in structure. SOLUTION: The bottom plate has a plurality of ribs 2 (2a, 2b, 2c, etc.), 3 (3a, 3b, 3c, etc.), which are arranged perpendicularly to each other and have a thickness of 3 to 10 mm. One-side surfaces of the ribs form a ground plane on the same plane, and a plurality of plate bodies 4 (4a, 4b, 4c, etc.), are arranged on the other-side surfaces of the ribs crossing each other, so as to form the same plane. Further, a plurality of openings 5 (51a, 51b, 52a, 52b, etc.), are formed between the plate bodies 4 and the ribs extending in one direction. The bottom plate is formed of a synthetic resin such that a grounding area with respect to a minimum unit area defined by the crossing ribs 2, 3 is set to the range of 10 to 45%.
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