A DAMPER-CONTROLLED SUNLIT GROWTH CHAMBER WITH INDEPENDENT CONTROL OFROOT TEMPERATURE

A damper-controlled sunlit growth chamber (SGC) with independent root temperature control for use in a greenhouse was designed, constructed and tested to facilitate the study of the combination effects of diffe rent air canopy and root zone temperatures on plants. Air temperature in the SGC was controlled with a motorized damper to adjust the ratio of the circulating air through a cooler Root temperature was maintaine d by controlling the soil temperature in a water-jacketed pot (WJP) pl aced inside the SGC. The SGC provided constant air temperature (adjust able from. IO to 30 degrees C) with three plant sections each at a dif ferent root temperature (adjustable from 10 to 30 degrees C). The thre e plant sections are geometrically identical to receive an equal amoun t of solar radiation. One combination of 20 degrees C air temperature and three root temperatures of 10, 20, and 30 degrees C were tested us ing strawberry plants in a greenhouse. The control precision was +/-0. 2 degrees C for air temperature and +/-0.5 degrees C for root temperat ure.