Strategies to control water and nutrient supplies to greenhouse crops. Areview [Review]

摘要

This paper introduces the approaches to automatic control of water and nutrient supplies to greenhouse crops. The traditional concepts of surplus irrigation and fertilization conflict with the environmental aspect. Therefore, water and nutrient demands of the plants must be met by the supplies. The generally used strategy is based on the application of standard nutrient solutions and frequent analyses of the nutrient solution concentration in the root environment. An improvement to this strategy is expected by using a feedback control, which takes ion sensitive measurements of the drainage water concentration or a feedforward control, where nutrient and water uptake are predicted using growth and transpiration models. Most of these approaches are still on a theoretical level and are far from being practical applications. Current strategies are directed towards the synchronization of uptake and supply, but future strategies should control plant functioning.