Methodological improvements when using thermal imagery in viticulture

Research output: Book chapter/Published conference paperConference paper

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Abstract

Infrared thermography (IRT) is a promising technology in viticulture using absolute or relative techniques. Methodological inconsistencies exist in the literature. Standardisation of measurements must be provided to growers before accurate deficit irrigation scheduling is implemented. Four field experiments are reported. Ambient temperature and relative humidity were similar when measured within a vineyard block and at the end of a row, but not wind speed. Wet and dry reference leaves were thermally stable 30 s after wetting and for 60 (exposed) to 90 s (shaded). The computed thermal time constant were influenced by wind puffs and ranged from 4 s to 14 s. 93% of triplicate thermographs of identical vine faces captured 2 min apart displayed a significant difference in mean temperature in all possible pairs. The confidence interval was however lower than the thermal camera accuracy error. Thermographs of heterogeneous canopies were segmented using digital photographs and the temperature range of vertical reference leaves. Most thermographs had over 40% of misclassified pixels. Finally, measurement errors of the infrared thermometer were shown to induce large error when using leaf temperature to evaluate stomatal resistance. In Conclusion, absolute canopy temperature varies over short periods of time, particularly when wind speed increases. This and the accuracy error of thermographers induce errors when computing stomatal resistance. Wind speed measurements should be taken close to the target canopy. Thermographs of reference leaves should be taken 30s after wetting. Heterogeneous canopies cannot yet benefit from thermal imagery for irrigation scheduling.
Original languageEnglish
Title of host publicationGroup of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO)
Place of PublicationMontpellier, France
PublisherLe Progres Agricole et Viticole
Pages181-184
Number of pages4
Publication statusPublished - 2011
EventGiESCO2011: 17th International Symposium - Asti - Alba (CN), Italy, Italy
Duration: 29 Aug 201102 Sep 2011

Publication series

Name
ISSN (Print)0369-8173

Conference

ConferenceGiESCO2011: 17th International Symposium
CountryItaly
Period29/08/1102/09/11

Fingerprint

viticulture
wind speed
canopy
heat
irrigation scheduling
stomatal conductance
leaves
temperature
thermography
thermometers
deficit irrigation
vineyards
standardization
cameras
vines
photographs
confidence interval
growers
ambient temperature
relative humidity

Cite this

Guisard, Y., Whish, J., & Scollary, G. (2011). Methodological improvements when using thermal imagery in viticulture. In Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO) (pp. 181-184). Montpellier, France: Le Progres Agricole et Viticole.
Guisard, Yann ; Whish, Jeremy ; Scollary, Geoffrey. / Methodological improvements when using thermal imagery in viticulture. Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). Montpellier, France : Le Progres Agricole et Viticole, 2011. pp. 181-184
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title = "Methodological improvements when using thermal imagery in viticulture",
abstract = "Infrared thermography (IRT) is a promising technology in viticulture using absolute or relative techniques. Methodological inconsistencies exist in the literature. Standardisation of measurements must be provided to growers before accurate deficit irrigation scheduling is implemented. Four field experiments are reported. Ambient temperature and relative humidity were similar when measured within a vineyard block and at the end of a row, but not wind speed. Wet and dry reference leaves were thermally stable 30 s after wetting and for 60 (exposed) to 90 s (shaded). The computed thermal time constant were influenced by wind puffs and ranged from 4 s to 14 s. 93{\%} of triplicate thermographs of identical vine faces captured 2 min apart displayed a significant difference in mean temperature in all possible pairs. The confidence interval was however lower than the thermal camera accuracy error. Thermographs of heterogeneous canopies were segmented using digital photographs and the temperature range of vertical reference leaves. Most thermographs had over 40{\%} of misclassified pixels. Finally, measurement errors of the infrared thermometer were shown to induce large error when using leaf temperature to evaluate stomatal resistance. In Conclusion, absolute canopy temperature varies over short periods of time, particularly when wind speed increases. This and the accuracy error of thermographers induce errors when computing stomatal resistance. Wind speed measurements should be taken close to the target canopy. Thermographs of reference leaves should be taken 30s after wetting. Heterogeneous canopies cannot yet benefit from thermal imagery for irrigation scheduling.",
keywords = "Open access version available, Infrared methodology, Infrared thermography, Irrigation scheduling",
author = "Yann Guisard and Jeremy Whish and Geoffrey Scollary",
note = "Imported on 03 May 2017 - DigiTool details were: publisher = Montpellier, France: Le Progres Agricole et Viticole, 2011. editor/s (773b) = Vittorino NOVELLO, Marco Bovio, Silvia Cavalletto; Event dates (773o) = 29 August - 2 September, 2011; Parent title (773t) = Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). ISSNs: 0369-8173;",
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language = "English",
publisher = "Le Progres Agricole et Viticole",
pages = "181--184",
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Guisard, Y, Whish, J & Scollary, G 2011, Methodological improvements when using thermal imagery in viticulture. in Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). Le Progres Agricole et Viticole, Montpellier, France, pp. 181-184, GiESCO2011: 17th International Symposium, Italy, 29/08/11.

Methodological improvements when using thermal imagery in viticulture. / Guisard, Yann; Whish, Jeremy; Scollary, Geoffrey.

Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). Montpellier, France : Le Progres Agricole et Viticole, 2011. p. 181-184.

Research output: Book chapter/Published conference paperConference paper

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AU - Guisard, Yann

AU - Whish, Jeremy

AU - Scollary, Geoffrey

N1 - Imported on 03 May 2017 - DigiTool details were: publisher = Montpellier, France: Le Progres Agricole et Viticole, 2011. editor/s (773b) = Vittorino NOVELLO, Marco Bovio, Silvia Cavalletto; Event dates (773o) = 29 August - 2 September, 2011; Parent title (773t) = Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). ISSNs: 0369-8173;

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N2 - Infrared thermography (IRT) is a promising technology in viticulture using absolute or relative techniques. Methodological inconsistencies exist in the literature. Standardisation of measurements must be provided to growers before accurate deficit irrigation scheduling is implemented. Four field experiments are reported. Ambient temperature and relative humidity were similar when measured within a vineyard block and at the end of a row, but not wind speed. Wet and dry reference leaves were thermally stable 30 s after wetting and for 60 (exposed) to 90 s (shaded). The computed thermal time constant were influenced by wind puffs and ranged from 4 s to 14 s. 93% of triplicate thermographs of identical vine faces captured 2 min apart displayed a significant difference in mean temperature in all possible pairs. The confidence interval was however lower than the thermal camera accuracy error. Thermographs of heterogeneous canopies were segmented using digital photographs and the temperature range of vertical reference leaves. Most thermographs had over 40% of misclassified pixels. Finally, measurement errors of the infrared thermometer were shown to induce large error when using leaf temperature to evaluate stomatal resistance. In Conclusion, absolute canopy temperature varies over short periods of time, particularly when wind speed increases. This and the accuracy error of thermographers induce errors when computing stomatal resistance. Wind speed measurements should be taken close to the target canopy. Thermographs of reference leaves should be taken 30s after wetting. Heterogeneous canopies cannot yet benefit from thermal imagery for irrigation scheduling.

AB - Infrared thermography (IRT) is a promising technology in viticulture using absolute or relative techniques. Methodological inconsistencies exist in the literature. Standardisation of measurements must be provided to growers before accurate deficit irrigation scheduling is implemented. Four field experiments are reported. Ambient temperature and relative humidity were similar when measured within a vineyard block and at the end of a row, but not wind speed. Wet and dry reference leaves were thermally stable 30 s after wetting and for 60 (exposed) to 90 s (shaded). The computed thermal time constant were influenced by wind puffs and ranged from 4 s to 14 s. 93% of triplicate thermographs of identical vine faces captured 2 min apart displayed a significant difference in mean temperature in all possible pairs. The confidence interval was however lower than the thermal camera accuracy error. Thermographs of heterogeneous canopies were segmented using digital photographs and the temperature range of vertical reference leaves. Most thermographs had over 40% of misclassified pixels. Finally, measurement errors of the infrared thermometer were shown to induce large error when using leaf temperature to evaluate stomatal resistance. In Conclusion, absolute canopy temperature varies over short periods of time, particularly when wind speed increases. This and the accuracy error of thermographers induce errors when computing stomatal resistance. Wind speed measurements should be taken close to the target canopy. Thermographs of reference leaves should be taken 30s after wetting. Heterogeneous canopies cannot yet benefit from thermal imagery for irrigation scheduling.

KW - Open access version available

KW - Infrared methodology

KW - Infrared thermography

KW - Irrigation scheduling

M3 - Conference paper

SP - 181

EP - 184

BT - Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO)

PB - Le Progres Agricole et Viticole

CY - Montpellier, France

ER -

Guisard Y, Whish J, Scollary G. Methodological improvements when using thermal imagery in viticulture. In Group of International Expertts of Vitivinicultural Systems for Co-operation (GiESCO). Montpellier, France: Le Progres Agricole et Viticole. 2011. p. 181-184