Effect of reducing the infrared radiation of sunlight on greenhouse temperature,leaf temperature,growth and yield

Infrared radiation, which is responsible for leaf temperatures that exceed the optimal for photosynthesis, was reduced by absorption in an aqueous CuSO₄ solution. A small greenhouse was constructed of double acryl plates through which a 0.5% CuSO₄ solution was circulated for infrared radiation filtration and cooling. The air temperature in this greenhouse never exceeded 30° C and the leaf temperature of the plants grown in this house was 10% lower than in a glass greenhouse. The yield of tomato plants grown in the acryl greenhouse, with infrared radiation filtration and receiving CO₂ enrichment during the entire light period, was not significantly increased as compared with the yield in the glass greenhouse with a similar CO₂ concentration. This may have been due to long periods with low light levels caused by extremely rainy and cloudy weather conditions, and by condensation on the inside surfaces of the acryl greenhouse caused by the high humidity.