L. Urgench State University A new method for measuring transpiration in tree trunks in the soil and climatic conditions of the region method described in this paper is based on thermal sensors dissipation. Sensors directly measure the rate of xylem sap, which can be correlated to the transpiration of trees calculated on unit area of active xylem. The principle of this method was developed by Dr. Andr Granierom in France and was widely accepted by the research community since 1996.

Xylem sap flow in plant magnified under conditions of intense transpiration when stomata are open. At a low intensity transpiration is low. The study used a relatively new method, are widely used abroad, which measures the movement of the active xylem. This simple method is ideal for the study of transpiration mature trees. In in Uzbekistan, this method is used for the first time.

Sensors of heat dissipation are two needles mounted directly on the depth of the active xylem. The method is based measuring differences in temperature (dT) between the heated upper and lower non-heated needle tip. With the use of controlled, well-known voltage, the upper needle continuously heated to a temperature of about 80C above around. With the passage of xylem sap along these needles, heated upper needle is cooled and the fixed temperature difference between the needles. If sap flow intensity, the difference in temperature between the two needles small, since heat flows from the top of the needle quickly dissipate. When sap flow is weak or close to zero, recorded the maximum difference in temperature or (dTmah).