Greenhouse Artificial Lighting Control

Industrial scale greenhouses have, during the last decade, reached a high level ofautomation. However, lighting control is in general still controlled manually because of the typeof lamps (High Pressure Sodium) that are used. With High Brightness LEDs about to reach themarket today sufficiently high power for greenhouse grown crops can be achieved, and this opensup for advanced lighting control. Optimized control will, however, be a difficult task because theneeds of the plants differ between individual plants, crops, time of the day, time of the growthcycle, temperature, and of course the natural ambient light. In this approach to this problem wedistinguish four different control loops: growth control, ambient light compensation, light stressdetection and recovery, and spectrum optimization, where the focus of this work is on the lattertwo. In particular it is shown here that light induced photoinhibition, decreasing photosyntheticyield and potentially damaging the plants, can be remotely detected in a light environment