Cross-validation on saplings of High-Capacity Tensiometer and Thermocouple Psychrometer for continuous monitoring of xylem water potential

Dainese Roberta, de Carvalho Faria Lima Lopes Bruna, Tedeschi Giuseppe, Lamarque Laurent J., Delzon Sylvain, Fourcaud Thierry, Tarantino Alessandro. 2022. Cross-validation on saplings of High-Capacity Tensiometer and Thermocouple Psychrometer for continuous monitoring of xylem water potential. Journal of Experimental Botany, 73 (1) : 400-412.

Résumé : The Pressure Chamber, the most popular method used to measure xylem water potential, is a discontinuous and destructive technique and therefore not suitable for automated monitoring. Continuous non-destructive monitoring could only be achieved until very recently via the Thermocouple Psychrometer (TP). We here present the High-Capacity Tensiometer (HCT) as alternative method for continuous non-destructive monitoring. This provided us with a unique chance to cross-validate the two instruments by installing them simultaneously on the same sapling stem. The HCT and the TP showed excellent agreement for xylem water potential < -0.5 MPa. Response to day/night cycles and watering was remarkably in phase, indicating excellent response time of both instruments despite substantially different working principles. For xylem water potential > -0.5 MPa, the discrepancies sometimes observed between the HCT and TP were mainly attributed to the kaolin paste used to establish contact between the xylem and the HCT, which becomes hydraulically poorly conductive in this range of water potential once dried beyond its air-entry value and subsequently re-wetted. Notwithstanding this limitation, which can be overcome by selecting a clay paste with higher air-entry value, the HCT has been shown to represent a valid alternative to the TP.

Mots-clés Agrovoc : physiologie végétale, xylème, potentiel xylème eau, potentiel hydrique, psychromètre

Mots-clés complémentaires : Tensiomètre

Mots-clés libres : High-Capacity Tensiometer, Pressure Chamber, Thermocouple Psychrometer, Xylem water potential, Water tension, Tree physiology

Classification Agris : F60 - Physiologie et biochimie végétale
K10 - Production forestière

Champ stratégique Cirad : CTS 7 (2019-) - Hors champs stratégiques

Agences de financement européennes : European Commission

Programme de financement européen : H2020

Auteurs et affiliations

• Dainese Roberta, University of Strathclyde (GBR)
• de Carvalho Faria Lima Lopes Bruna, University of Strathclyde (GBR)
• Tedeschi Giuseppe, Politecnico di Bari (ITA)
• Lamarque Laurent J., Université de Bordeaux (FRA)
• Delzon Sylvain, Université de Bordeaux (FRA)
• Fourcaud Thierry, CIRAD-BIOS-UMR AMAP (FRA) ORCID: 0000-0001-9475-7239
• Tarantino Alessandro, University of Strathclyde (GBR) - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/599212/)

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