ISHS Acta Horticulturae 440: International Symposium on Plant Production in Closed Ecosystems
THE PURSUIT OF OPTIMUM ENVIRONMENTS IN AUSTRALIAN GREENHOUSES |
| Author: | G. Connellan |
| Keywords: | design, environment, greenhouse, optimum, risk, ventilation |
| Abstract:
The demands on Australian greenhouse growers to produce quality ornamental plants and vegetables at competitive prices are increasing. The type of greenhouse structure that has been used by growers has changed significantly over the past two decades. The most common type of structure is a film covered, tunnel shape, multispan greenhouse. The major limitations of this structure are the extremes in environmental conditions (dry bulb temperature and relative humidity) experienced and the lack of installed environmental control equipment to provide the desired growing conditions for the crop. The variability in climate presents particular problems for Australian greenhouse producers. Seasonal variations at a site may range from -5°C in winter up to 40°C in summer. Maximum solar radiation levels typically reach 1050 Wm-2 in summer. Extremes in relative humidity are also experienced. An important step in achieving improvements in greenhouse environments is the identification and quantification of the optimum growing conditions for the crop. An awareness of the consequences of low quality or hazardous greenhouse environments is also fundamental. The major developments that have occurred, in recent times, to improve greenhouse environments have been in greenhouse design, covering materials and environmental control technologies such as heating systems and internal moveable screens. The single most important development has been the appreciation of the importance of effective ventilation in plastic greenhouses. | |
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