Xylem sap flow measurements in mango trees.
Lu P., Chacko E. K.
Author Affiliation: CSIRO Division of Horticulture, PMB 44, Winnellie, NT 0821, Australia.
: 339-350
Abstract : Measurement of whole-tree transpiration can provide an estimate of the irrigation requirement of mangoes. In order to evaluate the suitability of Granier's sap flow measuring system for mango trees, sap flow was compared with the transpiration obtained by gravimetric and 'cut-tree' methods. The Granier system estimated transpiration to within 6% of the true value. The system was tested on a 10-year-old field grown mango cv. Kensington Pride tree in the seasonally wet-dry tropics, Darwin, Australia. It showed some circumferential variation (east vs. west) in sap flow, although it responded well to changes in weather conditions and termination of irrigation in the middle of the measuring period. The daily whole-tree sap flow was higher during the wet season than during the dry season. During the dry season, the daily whole-tree water use measured by the sap flow method averaged 100 and 60 kg under irrigated and non-irrigated conditions, respectively. During the wet season, it was estimated to be 126 kg. A preliminary study on the depth profile of sap flux density in a large, mature mango tree, suggested that the radial variability and the circumferential variability in sap flux density in the trunk should be considered when scaling sap flux density to whole-tree water use.