Articles
Dynamics of radial sap flux density in olive trees subjected to different water deficit conditions
Article number
1409_3
Pages
15 – 22
Language
English
Abstract
Sap flow measurements are widely used to evaluate transpiration in woody species.
However, azimuthal and radial heterogeneity has been reported.
In this study, the radial behaviour of sap flow in adult olive trees was analysed under full irrigated (FI) and sustained deficit irrigation (SDI30), irrigated with 30% of crop evapotranspiration.
We used the compensation heat pulse method to evaluate the sap flux density.
The magnitude of radial sap flux density showed differences with the depth of trunk sectional area in both olive trees subjected to the two irrigation regimes.
For both irrigation treatments, the maximum sap flow rate was recorded at 15- and 25-mm depth.
In FI olive trees, the values of sap flux density were slightly higher at 15 than at 25 mm depth, while in SDI30 olive trees, there were more marked differences between the two depths, and sup flux density was highest at 25 mm.
In olive tree subjected to SDI30, with midday leaf water potential = -3.3 MPa, the density of sap flow in the outermost xylems vessels was very low, close to zero, indicating a degree of hydraulic dysfunction of the youngest xylem vessels because of the low soil water content.
Future attention to the ratio of daily values of sap flow densities in the inner to the outermost stem xylem as a water stress indicator will be needed to explore its potential for automatic irrigation.
However, azimuthal and radial heterogeneity has been reported.
In this study, the radial behaviour of sap flow in adult olive trees was analysed under full irrigated (FI) and sustained deficit irrigation (SDI30), irrigated with 30% of crop evapotranspiration.
We used the compensation heat pulse method to evaluate the sap flux density.
The magnitude of radial sap flux density showed differences with the depth of trunk sectional area in both olive trees subjected to the two irrigation regimes.
For both irrigation treatments, the maximum sap flow rate was recorded at 15- and 25-mm depth.
In FI olive trees, the values of sap flux density were slightly higher at 15 than at 25 mm depth, while in SDI30 olive trees, there were more marked differences between the two depths, and sup flux density was highest at 25 mm.
In olive tree subjected to SDI30, with midday leaf water potential = -3.3 MPa, the density of sap flow in the outermost xylems vessels was very low, close to zero, indicating a degree of hydraulic dysfunction of the youngest xylem vessels because of the low soil water content.
Future attention to the ratio of daily values of sap flow densities in the inner to the outermost stem xylem as a water stress indicator will be needed to explore its potential for automatic irrigation.
Authors
A.A. Fernandes-Silva, P. Marques
Keywords
compensation heat pulse, Olea europaea L., deficit irrigation, transpiration, radial sap flux density
Online Articles (64)