AUTHOR=Conesa María R. , Conejero Wenceslao , Vera Juan , Ruiz-Sánchez Ma Carmen 

TITLE=Assessment of trunk microtensiometer as a novel biosensor to continuously monitor plant water status in nectarine trees

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1123045

DOI=10.3389/fpls.2023.1123045

ISSN=1664-462X

ABSTRACT=<p>The objective of this work was to validate the trunk water potential (Ψ<sub>trunk</sub>), using emerged microtensiometer devices, as a potential biosensor to ascertain plant water status in field-grown nectarine trees. During the summer of 2022, trees were subjected to different irrigation protocols based on maximum allowed depletion (MAD), automatically managed by real-time soil water content values measured by capacitance probes. Three percentages of depletion of available soil water (α) were imposed: (i) α=10% (MAD=27.5%); (ii) α=50% (MAD=21.5%); and (iii) α=100%, no-irrigation until Ψ<sub>stem</sub> reached -2.0 MPa. Thereafter, irrigation was recovered to the maximum water requirement of the crop. Seasonal and diurnal patterns of indicators of water status in the soil-plant-atmosphere continuum (SPAC) were characterised, including air and soil water potentials, pressure chamber-derived stem (Ψ<sub>stem</sub>) and leaf (Ψ<sub>leaf</sub>) water potentials, and leaf gas exchange, together with Ψ<sub>trunk</sub>. Continuous measurements of Ψ<sub>trunk</sub> served as a promising indicator to determine plant water status. There was a strong linear relationship between Ψ<sub>trunk</sub><italic>vs.</italic> Ψ<sub>stem</sub> (R<sup>2</sup> = 0.86, <italic>p</italic>&lt;0.001), while it was not significant between Ψ<sub>trunk</sub><italic>vs.</italic> Ψ<sub>leaf</sub> (R<sup>2</sup> = 0.37, <italic>p</italic>&gt;0.05). A mean gradient of 0.3 and 1.8 MPa was observed between Ψ<sub>trunk</sub><italic>vs.</italic>Ψ<sub>stem</sub> and Ψ<sub>leaf</sub>, respectively. In addition, Ψ<sub>trunk</sub> was the best matched to the soil matric potential. The main finding of this work points to the potential use of trunk microtensiometer as a valuable biosensor for monitoring the water status of nectarine trees. Also, trunk water potential agreed with the automated soil-based irrigation protocols implemented.</p>