Methods for Controlling the Environment of Greenhouse Plants

Abstract

Methods are described for the partial regulation of the gas, temp., humidity, and light environment of greenhouse plants. The partial pressure of CO2 in the gas mixture supplied the plants is regulated by mixing air with CO2 from a cylinder; the volume of each constituent is measured with a standardized flow meter. The humidity of the gas mixtures is partially controlled by passing them over saturated solutions of NaCl. Natural illumination from the sun is supplemented in the winter months with 200-300 watt Mazda lamps, which are kept 1.0 to 1.5 ft. above the plants, and are so distributed that the intensity of the light received is about 250 foot-candles. The temp. of the greenhouse is regulated by steam heat, ventilators, electric fans, and the sprinkling of sand beds and walks. The intensity of the sunlight during the spring is reduced by means of shades, and in the summer by means of whitewash applied to the roof. Commercial CuSO4 distributed through the house prevents algal growth. Routine analyses, including meteorological observations, estimation of CO2, and determination of ultra violet light, are made periodically and recorded in a log book.