L. Liu et Pn. Walker, A DAMPER-CONTROLLED SUNLIT GROWTH CHAMBER WITH INDEPENDENT CONTROL OFROOT TEMPERATURE, Transactions of the ASAE, 40(6), 1997, pp. 1677-1683
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.