TY - JOUR
T1 - An insight to the performance of crop water stress index for olive trees
AU - Agam, N.
AU - Cohen, Y.
AU - Berni, J. A.J.
AU - Alchanatis, V.
AU - Kool, D.
AU - Dag, A.
AU - Yermiyahu, U.
AU - Ben-Gal, A.
N1 - Funding Information: The building and maintaining of the lysimeter facility was supported generously by the JCA Charitable Foundation (ICA Israel) . Thanks to Eugene Presnov of Gilat Research Center, Agricultural Research Organization of Israel, for technical assistance, to Asher Levi and Roman Brikman of the Institute of Agricultural Engineering, Agricultural Research Organization of Israel, for their crucial assistance in the acquisition of the thermal images, and to Alexander Goldberg of the Remote Sensing Laboratory, Blaustain Institutes for Desert Research, Ben-Gurion University of the Negev, for the analysis of the images.
PY - 2013/2/1
Y1 - 2013/2/1
N2 - Optimization of olive oil quantity and quality requires finely tuned water management, as increased irrigation, up to a certain level, results in increasing yield, but a certain degree of stress improves oil quality. Monitoring tools that provide accurate information regarding orchard water status would therefore be beneficial. Amongst the various existing methods, those having high resolution, either temporally (i.e., continuous) or spatially, have the maximum adoption potential. One of the commonly used spatial methods is the Crop Water Stress Index (CWSI). The objective of this research was to test the ability of the CWSI to characterize water status dynamics of olive trees as they enter into and recover from stress, and on a diurnal scale. CWSI was tested in an empirical form and in two analytical configurations. In an experiment conducted in a lysimeter facility in the northwestern Negev, Israel, irrigation was withheld for 6 days for 5 of 15 trees, while daily irrigation continued for the rest of the trees. After resuming irrigation, the trees were monitored for 5 additional days. Water status measurements and thermal imaging were conducted daily between 12:00 and 14:00. Diurnal monitoring (predawn to after dusk) of the same indicators was conducted on the day of maximum stress. Continuous meteorological data were acquired throughout the experimental period. Empirical and analytical CWSI were calculated based on canopy temperature extracted from thermal images. The empirical CWSI differentiated between well watered and stressed trees, and depicted the water status dynamics during the drought and recovery periods as well as on a diurnal scale. Analytical approaches did not perform as well at either time scale. In conclusion, the empirical CWSI seems to be promising even given its limitations, while analytical forms of CWSI still require improvement before they can be used as a water status monitoring tool for olive orchards. Practically, it is proposed to compute the wet temperature analytically and set the dry temperature to 5 °C higher than air temperature.
AB - Optimization of olive oil quantity and quality requires finely tuned water management, as increased irrigation, up to a certain level, results in increasing yield, but a certain degree of stress improves oil quality. Monitoring tools that provide accurate information regarding orchard water status would therefore be beneficial. Amongst the various existing methods, those having high resolution, either temporally (i.e., continuous) or spatially, have the maximum adoption potential. One of the commonly used spatial methods is the Crop Water Stress Index (CWSI). The objective of this research was to test the ability of the CWSI to characterize water status dynamics of olive trees as they enter into and recover from stress, and on a diurnal scale. CWSI was tested in an empirical form and in two analytical configurations. In an experiment conducted in a lysimeter facility in the northwestern Negev, Israel, irrigation was withheld for 6 days for 5 of 15 trees, while daily irrigation continued for the rest of the trees. After resuming irrigation, the trees were monitored for 5 additional days. Water status measurements and thermal imaging were conducted daily between 12:00 and 14:00. Diurnal monitoring (predawn to after dusk) of the same indicators was conducted on the day of maximum stress. Continuous meteorological data were acquired throughout the experimental period. Empirical and analytical CWSI were calculated based on canopy temperature extracted from thermal images. The empirical CWSI differentiated between well watered and stressed trees, and depicted the water status dynamics during the drought and recovery periods as well as on a diurnal scale. Analytical approaches did not perform as well at either time scale. In conclusion, the empirical CWSI seems to be promising even given its limitations, while analytical forms of CWSI still require improvement before they can be used as a water status monitoring tool for olive orchards. Practically, it is proposed to compute the wet temperature analytically and set the dry temperature to 5 °C higher than air temperature.
KW - Canopy temperature
KW - Crop water stress index
KW - Fully transpiring leaf
KW - Non-transpiring leaf
KW - Olive tree
KW - Water status
UR - http://www.scopus.com/inward/record.url?scp=84872128626&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.agwat.2012.12.004
DO - https://doi.org/10.1016/j.agwat.2012.12.004
M3 - Article
SN - 0378-3774
VL - 118
SP - 79
EP - 86
JO - Agricultural Water Management
JF - Agricultural Water Management
ER -
