PROBLEM TO BE SOLVED: To effectively and reliably reduce a defective growth incident rate of a plant to be cultivated.SOLUTION: In a hydroponic method, a nutrient liquid EC value x shows electric conductivity of an applicable nutrient liquid and an integrated photon flux density M is a product of a photosynthesis effective photon flux density I and a light irradiation time T×D. A correlation between the minimum integrated photon flux density M and the nutrient liquid EC value x, which is required so that a defective growth incident rate of a plant is a specified threshold value or less during a cultivation period T, is obtained as an optimum correlation K. To control the cultivation state, the nutrient liquid EC value x, the light irradiation time T×D, or the photosynthesis effective photon flux density I are adjusted so that the nutrient liquid EC value x during the cultivation period T and the integrated photon flux density M during the cultivation period T satisfy the optimum correlation K.COPYRIGHT: (C)2015,JPO&INPIT【課題】栽培植物の生育不良発生率を効果的かつ確実に低減する。【解決手段】施用する養液の電気伝導度を示す養液EC値x、及び、光合成有効光量子束密度Iと光照射時間T×Dとの積である積算光量子束密度Mについて、栽培期間Tにおける植物生育不良の発生率が設定閾値以下となるのに要する最小の積算光量子束密度Mと養液EC値xとの相関を最適相関Kとして求め、栽培状態の調整として養液EC値x又は光照射時間T×D又は光合成有効光量子束密度Iを調整することで、栽培状態を栽培期間Tにおける養液EC値xと栽培期間Tにおける積算光量子束密度Mとが最適相関Kを満足する値となる栽培状態に調整する。【選択図】図6
