Moisture content observation device, moisture content observation method, and cultivating device

A device for observing water content contained in a plant, the device comprising:

• a first light source which radiates a near infrared laser reference beam of a first wavelength having a characteristic in which light tends not to be absorbed in water while sequentially scanning toward the plant;
• a second light source which radiates a near infrared laser measuring beam of a second wavelength having a characteristic in which light tends to be absorbed in water while sequentially scanning toward the plant;
• an output unit that outputs an invisible light image indicating presence or absence of water contained in the plant;
• a water content calculation unit that repeatedly calculates the water content contained in each pixel area constituting the invisible light image based on reflection light of the near infrared laser reference beam and reflection light of the near infrared laser measuring beam, in a certain measurement period;
• and
• a controller that displays a time-transition of the water content, which is contained in the pixel area from start to end of a measurement period, calculated by the water content calculation unit on a display unit,
• wherein the controller fixedly determines a set of pixel areas in which the water content calculated by the water content calculation unit exceeds a threshold level at the start of the measurement period, out of all pixel areas constituting the invisible light image, as an observation target portion on the plant.