Articles
Midday stem water potential baseline for California Manzanillo table olive orchards
Article number
1335_22
Pages
189 – 196
Language
English
Abstract
Midday stem water potentials (SWP) diagnose water status and therefore can be used to prevent under or over irrigation.
To interpret SWP measurements in California table olive orchards, a baseline was developed for Manzanillo trees in five commercial low volume irrigated olive orchards in Californias northern Sacramento Valley.
The baseline predicts the expected SWP reading when soil moisture is not limiting and contributing to tree stress.
Baseline SWPs vary by plant species and are influenced by changing climatic conditions.
A baseline was developed by collecting SWP, climatic, and irrigation data over a range of weather conditions.
These data were then correlated with vapor pressure deficit (VPD) to develop a baseline model that predicts SWP in olive trees.
The best fit linear regression model for predicting baseline SWP levels in table olive was achieved by calculating VPD based upon air temperature and relative humidity measured in olive orchards where soil moisture was not limited.
However, calculating VPD based upon ambient temperature and relative humidity measured at the nearest CIMIS short grass reference weather station also provided a reliable prediction of baseline SWP. Even when soil moisture is not limiting, baseline SWP levels are expected to range from about -1.1 to -1.8 MPa tension in table olive when temperature ranges from 30 to 40°C and 25 to 65% relative humidity.
This research indicates that fully irrigated baseline olive SWP readings will be significantly more negative than deciduous tree crops such as almond, walnut or prune.
Under hot, dry conditions this predictive model shows the capacity to distinguish between instances when an orchard is fully irrigated and more negative SWPs are produced by the weather conditions, from times when more negative SWPs indicate significant tree water stress and irrigation is appropriate.
To interpret SWP measurements in California table olive orchards, a baseline was developed for Manzanillo trees in five commercial low volume irrigated olive orchards in Californias northern Sacramento Valley.
The baseline predicts the expected SWP reading when soil moisture is not limiting and contributing to tree stress.
Baseline SWPs vary by plant species and are influenced by changing climatic conditions.
A baseline was developed by collecting SWP, climatic, and irrigation data over a range of weather conditions.
These data were then correlated with vapor pressure deficit (VPD) to develop a baseline model that predicts SWP in olive trees.
The best fit linear regression model for predicting baseline SWP levels in table olive was achieved by calculating VPD based upon air temperature and relative humidity measured in olive orchards where soil moisture was not limited.
However, calculating VPD based upon ambient temperature and relative humidity measured at the nearest CIMIS short grass reference weather station also provided a reliable prediction of baseline SWP. Even when soil moisture is not limiting, baseline SWP levels are expected to range from about -1.1 to -1.8 MPa tension in table olive when temperature ranges from 30 to 40°C and 25 to 65% relative humidity.
This research indicates that fully irrigated baseline olive SWP readings will be significantly more negative than deciduous tree crops such as almond, walnut or prune.
Under hot, dry conditions this predictive model shows the capacity to distinguish between instances when an orchard is fully irrigated and more negative SWPs are produced by the weather conditions, from times when more negative SWPs indicate significant tree water stress and irrigation is appropriate.
Authors
L. Milliron, A. Fulton, W. Krueger, R. Rosecrance
Keywords
SWP, pressure chamber, water stress, irrigation, ETc, VPD
Online Articles (92)