Measurements of Sap Flow in the Roots, Trunk and Shoots of an Apple Tree Using Heat Pulse and Heat Balance Methods

Abstract

To understand more deeply water dynamics in an apple tree, we examined diurnal changes in sap flow in the shoots, trunk and roots of a 10-year old apple tree (cv. Splendor), using to advantage both the heat balance and heat pulse methods. There was little time lag between sap flow in the trunk and the root, suggesting a high hydraulic conductivity between them. The time lag between the start of shoot sap flow, and that of trunk and root, after sunrise was estimated to be about 30 min. Considering the finding of Schulze et al. (1985) that the main water store is located in the tree crown, it appeared here in our experiment that the main storage element of the apple tree was also the crown. © 1997, The Society of Agricultural Meteorology of Japan. All rights reserved.