Characterization and Analysis of the Effects of Greenhouse Climate Control Equipment on Greenhouse Microclimate and Crop Response

An overview of the recent scientific and technical advances on issues concerning the greenhouse microclimate, control and management in Mediterranean regions is presented and discussed. Special emphasis is given on the effects of climate control equipment in: (a) greenhouse microclimate and (b) crop response. The main greenhouse climate control systems presented and discussed are the heating, dehumidification, ventilation, shading and cooling systems. These systems are the most widely used for greenhouse climate control especially in the Mediterranean area. In these areas, natural ventilation and whitewashing are the most common methods/systems used for greenhouse climate control during summer, since they require less energy, less equipment operation and maintenance and are much cheaper to install than other cooling systems. However, generally these systems are not sufficient for extracting the excess energy during sunny summer days and therefore, other cooling methods such as forced ventilation combined with evaporative cooling (mist or fog system, sprinklers, wet pads), are used. On the other hand, during the winter period, heating and dehumidification are necessary for a standard quality production. Optimal greenhouse climate control became more important in the latter part of the 20th century, when concerns about food safety, environmental pollution stimulated extensive research in the development of Integrated Production and Protection systems aiming at a significant reduction of pesticides use. The prospective and needs for future research and development in greenhouse climate control are presented in the conclusion. Special emphasis is given to the necessity to combine both physical and ecophysiological studies, because of the crucial role played by the crop in determining the microclimate in greenhouses.