PROBLEM TO BE SOLVED: To accurately grasp just chlorophyll fluorescence in measurement by means of a pulse amplitude modulation method using action light of a wavelength that actually grows plants.SOLUTION: A measurement operation controller (53b) makes a second LED light source (20b) irradiate a plant (12) with saturated pulse light (SP) and makes a fluorescence intensity measurement unit (40) measure intensity of fluorescence during a period from the time a first LED light source (20a) stops irradiating the plant (12) with action light (AL) until intensity of chlorophyll fluorescence starts decreasing from a level observed when the action light (AL) was turned off.SELECTED DRAWING: Figure 6COPYRIGHT: (C)2018,JPO&INPIT【課題】実際に植物が生長する波長の作用光を用いたパルス増幅変調法での測定において、クロロフィル蛍光のみを精度良く把握する。【解決手段】測定動作制御部(53b)は、第1LED光源(20a)による作用光(AL)の植物(12)への照射が停止してからクロロフィル蛍光の強度が該作用光(AL)の停止時よりも減少し始めるまでの間に、植物(12)への飽和パルス光(SP)の照射を第2LED光源(20b)に行わせるとともに蛍光強度測定部(40)に蛍光の強度の測定を行わせる。【選択図】図6
