Articles
A ground-based mobile platform to measure and map canopy thermal indices in a nectarine orchard
Article number
1373_20
Pages
147 – 156
Language
English
Abstract
Precise irrigation management tailored to plant water status (PWS) is paramount to sustain agriculture in a climate change and water scarcity scenario.
Canopy temperature (Tc), delta temperature [dT = Tc − ambient temperature (Ta)] and crop water stress index (CWSI) can be used to describe PWS. This study aimed to test a mobile platform sensor system (Green Atlas Cartographer equipped with infrared temperature sensors) for rapid measurements of Tc (and derivation of dT and CWSI) in a nectarine orchard.
The study was conducted on mature high-density September Bright nectarine trees under four irrigation treatments 100% of crop evapotranspiration (ETc), 40% ETc, 20% ETc and no irrigation (0% ETc). The orchard was scanned using Cartographer to measure Tc.
A local weather station was used to obtain Ta and derive dT, and two methods were used to calculate CWSI a more traditional approach that used the relationship between dT and VPD (CWSI-I) and a statistical approach that used the 99% prediction intervals of the relationship between Tc and VPD (CWSI-II). Correlations of Tc, dT, CWSI-I and CWSI-II with leaf water potential (Ψleaf) and irrigation treatments were tested.
Tc, dT, CWSI-I and CWSI-II were found to be significantly inversely related to Ψleaf and irrigation treatments when measurements were obtained between 1300 and 1915 h (AEDT) at different dates.
CWSI-II outperformed CWSI-I in describing a more realistic PWS gradient over time.
Spatial maps of Tc revealed clear visual separations of deficit irrigation treatments.
We contend that Tc can be used per se as a tool to assess spatial variability of PWS at single points in time when Tc measurements are taken over a relatively short timeframe where Ta and vapour pressure deficit can be considered constant.
However, dT, CWSI-I and CWSI-II are the preferred indices of PWS for temporal comparisons between different days and/or times of the day.
Our results confirm the suitability and utility of ground-based vehicles for fast and on-demand assessments of spatial and temporal variability of PWS in orchards.
Canopy temperature (Tc), delta temperature [dT = Tc − ambient temperature (Ta)] and crop water stress index (CWSI) can be used to describe PWS. This study aimed to test a mobile platform sensor system (Green Atlas Cartographer equipped with infrared temperature sensors) for rapid measurements of Tc (and derivation of dT and CWSI) in a nectarine orchard.
The study was conducted on mature high-density September Bright nectarine trees under four irrigation treatments 100% of crop evapotranspiration (ETc), 40% ETc, 20% ETc and no irrigation (0% ETc). The orchard was scanned using Cartographer to measure Tc.
A local weather station was used to obtain Ta and derive dT, and two methods were used to calculate CWSI a more traditional approach that used the relationship between dT and VPD (CWSI-I) and a statistical approach that used the 99% prediction intervals of the relationship between Tc and VPD (CWSI-II). Correlations of Tc, dT, CWSI-I and CWSI-II with leaf water potential (Ψleaf) and irrigation treatments were tested.
Tc, dT, CWSI-I and CWSI-II were found to be significantly inversely related to Ψleaf and irrigation treatments when measurements were obtained between 1300 and 1915 h (AEDT) at different dates.
CWSI-II outperformed CWSI-I in describing a more realistic PWS gradient over time.
Spatial maps of Tc revealed clear visual separations of deficit irrigation treatments.
We contend that Tc can be used per se as a tool to assess spatial variability of PWS at single points in time when Tc measurements are taken over a relatively short timeframe where Ta and vapour pressure deficit can be considered constant.
However, dT, CWSI-I and CWSI-II are the preferred indices of PWS for temporal comparisons between different days and/or times of the day.
Our results confirm the suitability and utility of ground-based vehicles for fast and on-demand assessments of spatial and temporal variability of PWS in orchards.
Authors
A. Scalisi, M.G. OConnell, D.M. Whitfield, J. Underwood, I. Goodwin
Keywords
drought, irrigation, P. persica (L.) Batsch, sensors, thermography
Groups involved
- Division Plant-Environment Interactions in Field Systems
- Division Temperate Tree Fruits
- Division Temperate Tree Nuts
- Division Precision Horticulture and Engineering
- Division Vegetables, Roots and Tubers
- Division Ornamental Plants
- Division Tropical and Subtropical Fruit and Nuts
- Division Vine and Berry Fruits
- Division Greenhouse and Indoor Production Horticulture
- Division Landscape and Urban Horticulture
- Commission Agroecology and Organic Farming Systems
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