Sap Flow Measurement in Japanese Pear Using the Granier Method

Abstract

To apply a technique to estimate correctly and easily the long-term water use in Japanese pear under the root zone restriction cultivation for irrigation, the Granier method of sap flow measurement was compared with the measurement of transpiration using a balance. The sap flow rate was calculated by multiplying the sap flow velocity, given by Granier's original equation, by the sapwood area, which was estimated using the dyeing method. The daily sap flow rate, as measured by the Granier method, correlated well with the daily transpiration rate during the growing period. In addition, provided heart-wood had not developed, the daily sap flow rate was measured directly using the Granier method by multiplying the sap flow velocity by the cross-sectional area, excluding the bark. This suggests that the Granier method can be used to measure the daily transpiration rate in Japanese pear to produce long-term estimates of daily water use for irrigation throughout the growing period. © 2009, The Society of Agricultural Meteorology of Japan. All rights reserved.