World-wide Use of Plastics in Horticultural Production

o technological development has modified so much the course of controlled environment agriculture in the production of fruits, vegetables, flowers, and ornamentals as the recent widespread use of plastic films and related materials.Plastic films are used extensively for the design and covering of new greenhouses; the covering of old conventional glass greenhouses; for air-inflated, self-contained, or supported bubble houses; as interior curtains and external barriers to reduce heat loss in conventional greenhouses; and for the containment of CO 2 -enriched atmospheres.Plastic films also are used for constructing high and low tunnels or covers for many row crops, protective covering of seed beds, and for soil mulches.Plastic tubes, laterals, and drip lines are important components of drip irrigation systems for high-value horticultural crops, which now cover 300,000 ha world-wide.Drip irrigation is often a component with plastic soil mulches, crop rowcovers, and plastic greenhouses.Recent introductions using plastic films include peat modules, bag cultures, rockwool, the nutrient-film technique, and nonvariable root environments for field-grown tomatoes (Geraldson, 1982;Wittwer, 1981).Flats, pots, and even labels for growing plants in greenhouses involve plastics.Plastic components contribute to the precise control of top and root environments of plants.In many modern greenhouses, all plant growing structures, other than the root media itself, are plastic (Fig. 1).