Effects of insulating foams between double polythylene films on light transmission, growth and productivity of greenhouse tomato plants grown under supplemental lighting

Energy saving in northern areas is major concerns of the greenhouse industry. Sunare of Canada has developed a new liquid-foam technology which generates and distributes specific liquid foam between two polyethylene films used as a greenhouse covering material. The effects of insulating foams on light transmission and on the growth and productivity of tomato plants (Lycopersicon esculentum Mill) were investigated. Two greenhouses were used in this experiment: (1) a control greenhouse (without the Sunare technology); and (2) a prototype greenhouse equipped with the Sunare technology. The experiment consisted in injecting liquid foam between two films from every night to increase greenhouse insulation and decrease energy consumption. Tomato plants were grown using high-pressure sodium lamps (HPS) lamps providing 120 mu mol m(-2) s(-1) for 16 hours per day. Greenhouse climate (air temperatures and air relative humidity), energy consumption, light transmission, and the growth, productivity and quality of tomato plants were measured in each greenhouse. Three tomato cultivars were used: Trust, Blitz and Rhapsodie. The results of the winter experiment indicate that the use of this technology reduced energy consumption by 62% without reducing tomato yields. Applications of Sunarc technology for greenhouse insulation will be discussed as well as the possibility of combining this technology with supplemental lighting to provide an energy-independent greenhouse.