PROBLEM TO BE SOLVED: To suitably select counterions supplied with the ions of an insufficient fertilizer component, when supplying the fertilizer component which is insufficient in a nutrient solution.SOLUTION: The present invention comprises a plant cultivation tub 10 to which a nutrient solution containing a fertilizer component required for the cultivation of plant X is supplied, an ion concentration measuring unit S2 for measuring the ion concentration contained in the nutrient solution, a determination unit 53 for determining an insufficient fertilizer component that is insufficient in the nutrient solution based on the measurement result of the ion concentration measuring unit S2, wherein a determination part 53 is configured to determine the type of the counterion supplied to the nutrient solution together with the ion of the insufficient fertilizer component, using as a parameter at least one of the variety of the plant X, the growth timing of the plant X, the function provided for the plant X, the health condition of the plant X, or the degree of harm to the human body of the counterion.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2017,JPO&INPIT【課題】養液に不足している肥料成分を供給する際に、不足の肥料成分のイオンとともに供給される対イオンを好適に選択する。【解決手段】植物Xの育成に必要な肥料成分を含む養液が供給される植物育成槽10と、養液に含まれるイオン濃度を測定するイオン濃度測定部S2と、イオン濃度測定部S2の測定結果に基づき、養液に不足している不足肥料成分を判断する判断部53とを具備し、判断部53が、不足肥料成分のイオンとともに養液に供給される対イオンの種類を、植物Xの品種、植物Xの成長時期、植物Xに備えさせる機能、植物Xの健康状態、又は対イオンの人体に対する害の程度のうち少なくとも1つをパラメータとして決定するようにした。【選択図】図1
