Articles
The CWSI non-water stress baseline for pistachio trees depends on soil management practices
Article number
1409_11
Pages
73 – 78
Language
English
Abstract
The crop water stress index (CWSI) is based on the difference between canopy and air temperature (Tc-Ta), and it has been extensively used for annual crops.
The identification of a non-water-stressed baseline (NWSB) is a necessary component of the CWSI, being commonly expressed as a linear relationship between (Tc-Ta) and the atmospheric vapor pressure deficit (VPD). However, scientific evidence has revealed that this relationship varies throughout the day and with environmental and management conditions.
In the last few years, fruit and nut growers have increasingly adopted winter cover cropping as an orchard floor management practice, leaving vegetation residue on the ground of row middles during the growing season for mulching purposes.
Therefore, the objective of this work was to determine the NWSB for micro-irrigated pistachio orchards with mulching residues from cover crops and to assess the sensitivity of the CWSI to the NWSB. The experiment was conducted in a mature, micro-irrigated pistachio orchard grown on a clay-loam soil in the southern San Joaquin Valley of California with two treatments: i) conventional floor management with clean-cultivated inter-rows; and ii) row middles with winter cover cropping and vegetation residues left on the ground during the growing season.
Results showed a differential evolution with time of the slope and intercept values of the NWSB between the clean-cultivated and cover cropped inter-row.
Furthermore, the sensitivity analysis revealed that the CWSI is more sensitive to the NWSB values when the crop experiences stress conditions than when the crop is well-watered.
Additionally, the variation observed in the CWSI decreased as VPD increased.
These findings highlight that the CWSI is more sensitive in the presence of mulching cover than for a clean-cultivated floor and, consequently, the need to consider the imagery acquisition time and the floor management practice when deriving the tree NWSB with remote sensing.
The identification of a non-water-stressed baseline (NWSB) is a necessary component of the CWSI, being commonly expressed as a linear relationship between (Tc-Ta) and the atmospheric vapor pressure deficit (VPD). However, scientific evidence has revealed that this relationship varies throughout the day and with environmental and management conditions.
In the last few years, fruit and nut growers have increasingly adopted winter cover cropping as an orchard floor management practice, leaving vegetation residue on the ground of row middles during the growing season for mulching purposes.
Therefore, the objective of this work was to determine the NWSB for micro-irrigated pistachio orchards with mulching residues from cover crops and to assess the sensitivity of the CWSI to the NWSB. The experiment was conducted in a mature, micro-irrigated pistachio orchard grown on a clay-loam soil in the southern San Joaquin Valley of California with two treatments: i) conventional floor management with clean-cultivated inter-rows; and ii) row middles with winter cover cropping and vegetation residues left on the ground during the growing season.
Results showed a differential evolution with time of the slope and intercept values of the NWSB between the clean-cultivated and cover cropped inter-row.
Furthermore, the sensitivity analysis revealed that the CWSI is more sensitive to the NWSB values when the crop experiences stress conditions than when the crop is well-watered.
Additionally, the variation observed in the CWSI decreased as VPD increased.
These findings highlight that the CWSI is more sensitive in the presence of mulching cover than for a clean-cultivated floor and, consequently, the need to consider the imagery acquisition time and the floor management practice when deriving the tree NWSB with remote sensing.
Authors
J.M. Ramírez-Cuesta, D. Zaccaria, K. Shapiro, R.L. Snyder, P. Steduto
Keywords
air temperature, canopy temperature, cover crop, crop water stress, mulching, precision agriculture
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