Control of water supply in closed growing systems in a greenhouse

摘要

In the tests presented, direct feedback of drain flow, rather than a predictive uptake model, controls the supply of nutrient solution to plants in a greenhouse. Feed-back eontrol of the measured drain water flow keeps it on a constant set value. Water uptake by the plant is considered as a disturbance of the drain flow control loop. A dynamic model is constructed from noise response data of the supply process for three different growing systems. Results are presented, that show the compensation as a result of feedback control of changes in water uptake by the plant, due to variations in global radiation.