Approaches for mitigating the environmental impact of greenhouse horticulture

Greenhouse horticulture creates environmental issues of different kinds. Use of energy for heating and lighting and pollution by pesticides and nutrients are major known problems, but impacts on the landscape and light emissions from supplementary lighting have also attracted attention. However, increased productivity and new technologies provide possibilities for reducing the impact of greenhouse horticulture on the surrounding environment. This thesis presents various approaches for moving greenhouse horticulture towards sustainability. Three main directions are examined: use of recirculating hydroponic systems and slow filters; use of biosurfactants to control root disease; and use of light-emitting diode (LED) technology to save energy and reduce the use of chemical growth retardants. Recirculating systems with slow filters functioned satisfactorily with respect to phytosanitary issues. The resident microflora in these systems possessed the ability to produce biosurfactants that were shown to control zoosporic pathogens. LED lighting proved useful for growth control of flowering plants. These three technologies represent good examples of measures to create the greenhouse of the future.