Abstract
In order to get quantitative information on the physiological status of field trees, we tried for 3 years simultaneous and continuous measurement of trans-root electric potential (TRP) by means of the electro-radicograph system which is developed by ourselves and sap-flow by means of the Granier type sap-flow-meters, in the field trees in a mountain area. We had accumulated ample experience on the electro-radicograph, but on the sap-flow system, we had no experience except model experiments in our laboratory. Under the very hard conditions in the mountain area, we met a number of unexpected troubles, to find finally the main obstacle was the bad insulation in the electric circuits caused by the invasion of rain water. Besides, a fundamental technical error in constructing the circuit was discovered in the most of the sap-flow meters imported. Here reported the process how to conquer the difficulties and the final solutions of the problems were.
