Thermoelectric module cooling for photosynthesis chambers in plant nutrition studies 1 |
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| Authors: | K Ohki C O Weldon |
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| Institution: | Department of Agronomy , University of Georgia , Griffin, GA, 30212–5099 |
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| Abstract: | The water cooled system for controlling air temperature in photosynthesis assimilation chamber is cumbersome and requires a water tight system consisting of a double‐jacketed chamber. Manipulation of temperature control from one air temperature to another requires the adjustment of water bath temperatures. A simplified system for the air temperature control of the assimilation chamber and heat removal under high photon flux density would be desirable. An effective thermoelectric module cooling and heating system for a photosynthesis chamber was developed and evaluated for wheat (Triticum aestivum L.), sorghum Sorghum bicolor (L.) Moench], and soybean Glycine max (L.) Merr.] Air temperature variations within a chamber were maintained within 0.4°C, 0.9°C, and 0.3°C for the wheat, sorghum, and soybean chambers, respectively. The thermoelectric module system is simple and provides sufficient cooling and heating capacities to maintain chamber air temperature from 20°C to 30°C with 1100 μmol m‐2 s‐1 photon flux density for photosynthesis and dark respiration studies. Air temperature within a photosynthesis chamber during photosynthesis in plant nutrition studies is one of the important environmental parameters that must be controlled. Due to excessive heat under the relatively high photon flux density used in photosynthesis measurements, air temperature has been traditionally cooled and controlled by passing chilled water through double walled water‐jacket chambers3,5,7,8,12,13. Although the water cooled double‐jacket system has been successful in controlling temperature, maintaining water tight systems has been a problem. To alleviate some of the problems of a double‐jacketed system, air was cooled by passing over a water‐cooled radiator placed below the leaf4,11 . Under conditions of relatively high photon flux densities (1100 ymol m‐2 s‐1), water‐cooled systems do not provide sufficient cooling capacity to maintain 25°C or less air temperature. Mauney, et al.6 reported photosynthetic data obtained from cuvettes that were electrically cooled by the Peltier device, but no details of the system were provided. In later studies9,10,14, Peltier‐cooled systems appeared as a simple alternative to water‐cooled systems. This paper reports the details on an effective thermoelectric module cooling and heating system based on the Peltier principle for photosynthesis chambers. |
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| Keywords: | Photosynthesis assimilation chamber Wheat (Triticum aestivum L ) Sorghum [Sorghum bicolor (L ) Moench] Soybean [Glycine max (L ) Merr ] Peltier effect Dark respiration |
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