1 research outputs found
Calibration of sap flow estimated by the compensation heat pulse method in olive, plum and orange trees: relationships with xylem anatomy
10 páginas, 6 figuras, 3 tablas, 42 referencias.-- [email protected] compensation heat pulse method is widely
used to estimate sap flow in conducting organs of woody
plants. Being an invasive technique, calibration is crucial to derive
correction factors for accurately estimating the sap flow
value from the measured heat pulse velocity.We compared the
results of excision and perfusion calibration experiments made
with mature olive (Olea europaea L. ‘Manzanilla de Sevilla’),
plum (Prunus domestica L. ‘Songal’) and orange (Citrus sinensis
(L.) Osbeck. ‘Cadenero’) trees. The calibration experiments
were designed according to current knowledge on the
application of the technique and the analysis of measured heat
pulse velocities. Data on xylem characteristics were obtained
from the experimental trees and related to the results of the calibration
experiments. The most accurate sap flow values were
obtained by assuming a wound width of 2.0 mm for olive and
2.4 mm for plum and orange. Although the three possible
methods of integrating the sap velocity profiles produced similar
results for all three species, the best results were obtained by
calculating sap flow as the weighted sum of the product of sap
velocity and the associated sapwood area across the four sensors
of the heat-pulse-velocity probes. Anatomical observations
showed that the xylem of the studied species can be
considered thermally homogeneous. Vessel lumen diameter in
orange treeswas about twice that in the olive and plum, but vessel
densitywas less than half. Total vessel lumen area per transverse
section of xylem tissue was greater in plum than in the
other species. These and other anatomical and hydraulic differences
may account for the different calibration results obtained
for each species.This work was financed by the Direción General de Investigación of
the Spanish Ministry of Science and Technology (Research Projects
AGL2002-04048-CO3-01 and PTR1995-0693-OP-02-01).Peer reviewe