ISHS Acta Horticulturae 633: XXVI International Horticultural Congress: Protected Cultivation 2002: In Search of Structures, Systems and Plant Materials for Sustainable Greenhouse Production
THE POTENTIAL OF RETRACTABLE ROOF GREENHOUSES TO DOMINATE GREENHOUSE DESIGNS IN THE FUTURE |
| Author: | R. Vollebregt |
| Keywords: | ventilation, protection, transpiration, water stress, soil temperatures, abscisic acid |
| Abstract:
Retractable roof greenhouses have been commercially available since the early 1990’s. While roof designs are becoming standardized, there is a lack of understanding of the positive impacts of retractable roof greenhouses on plant health, growth, crop management practices, and the subsequent production costs/savings. Retractable roof greenhouses appear to optimize both photosynthesis and the levels of beneficial plant stress to ensure that it develops the strength, disease and insect resistance not present when plants are grown inside conventional greenhouses. Retractable roof greenhouses have been shown to help prevent many of the problems of field and container grown plants by protecting leaves and roots from environmental extremes such as excessive or insufficient cold, heat, rain, or wind, and by preventing disorders associated with insufficient transpiration and the resultant lack of water stress typical in conventional greenhouse environments. This is possible because retractable roof greenhouses can create an outdoor, greenhouse and modified greenhouse environment simply by the positioning of the roof, walls and curtain systems. Data has shown that clear poly films used for retractable roof greenhouses (about 25% shading) are more effective at preventing heat buildup in a container compared to either no roof or 50% black shade cloth. Plant responses in retractable roof greenhouses include stronger root systems, reduced internode lengths, thicker cuticles, fewer root and foliar diseases, fewer insect pests, and less stress and shock following transplanting. Chemical fungicide, growth regulator and pesticide applications have been reduced by 10% to 100%. Management has an improved ability to ‘time’ the crop. Growers of outdoor crops have found benefits including up to a 50% reduction in crop production cycles, and about a 50% reduction in summer water usage. Retractable roof greenhouses will cause a rewriting of crop management strategies, as well as guidelines for how greenhouses are built and where they are built. | |
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