Some Improvement and Measurement of the Thermoelectric Method for Measuring Water Flow Rates in Rice Plants

Abstract

1. Thermoelectric method is advantageous in that repeated measurements can be made on the same intact plant either in the laboratory or under field conditions. There is no injury to the plant tissues and the normal physiological processes are not disturbed because all measurements are made externally on the stem. 2. This papar presents some of the improvement of the thermoelectric method that have been recently developed and used successfully. The different applications of the method presented here, and such a device can be used for further studies in problems concerned with the soilplant-water system. 3. The measuring circuit consisted of the modified wheatstone-bridge with a measuring thermistor in one arm and a compensatory thermistor in another arm of the bridge. Then measurement could be done even in the condition when the temperature varied quickly. 4. Over a period of time following an irrigation, water uptake and movement rates decrease as soil moisture becomes less available. 5. When the lodged stem was raised up, it was immediately apparent that high tensions existed within the rice crop because of the increased water absorption and movement rates in the stem. As the internal "negative" or "suction" pressure of the plant was released, the rates of water absorption and movement within the crop became slower as shown in figure 7.