Irrigation system and cultural practices for crop production under control environment production system

Historically the main role of greenhouses in the tropics has been passive, namely: in the humid tropics as a rain shelter; in the and tropics to protect the crop from low humidity. It may be timely to consider using tropical greenhouses actively to improve both the above and below the ground environments. Improvements in irrigation delivery systems have the potential to modify the root-zone environment in a very positive manner. Irrigation delivery systems for temperate climate greenhouse crops have changed tremendously over the past 50 years, however many of these systems have not become established in tropical and sub-tropical greenhouses. In temperate climates the switch from soil based growing systems to soilless systems has resulted in huge improvements in the control of the root environment (particularly for water and nutrients) with consequential improvements in both yield and quality. Soilless (hydroponic) systems have enabled plant water stress to be minimized, and by using a well drained medium (or no medium) recirculating hydroponic systems have been developed, and the questions of when and how much water to apply have become superfluous. Recirculating hydroponic systems are of many different types (e.g. deep-flow, aeroponics, etc.) but all provide for very efficient (sustainable) water and nutrient use, with a down side that any plant pathogens in the root system are also recirculated. Choice of irrigation system may also permit improved control of the root environment (e.g. temperature in aeroponics).