|Authors: ||C. Ballester, M. Castiella, U. Zimmermann, S. Rüger, M.A. Martínez Gimeno, D.S. Intrigliolo|
|Keywords: ||citrus, deficit irrigation, drought stress, leaf turgor, pressure sensors, stem water potential|
Further improvement on irrigation management requires continuous plant water status monitoring.
The non-invasive ZIM-probe measures the pressure (Pp) transfer function through a patch of an intact leaf, which is inversely correlated with the turgor pressure.
Data are sent wireless in real-time by telemetry to an internet server via a mobile phone network where it is available to be analyzed.
In this work, the detection of water stress by measuring relative changes in turgor pressure with the ZIM-probe was evaluated in clementine and persimmon trees.
Ten trees of both species were equipped with two ZIM-probes each located at the east side of the canopy.
The ZIM-probes were used over several months during which half of the trees were subjected to two drought cycles.
Concomitant measurements of stem water potential (ψs) were taken at midday in both orchards during the drought periods.
Additionally, determinations of ψs and stomatal conductance (gs) were also performed during 1-2 days at hourly intervals in the clementine and persimmon orchards, respectively, to study the existing relationship of these classical indicators with the leaf turgor pressure.
Results showed that diurnal Pp values increased in non-irrigated clementine trees when water restrictions were imposed.
Persimmon drought-stressed trees, on the other hand, showed different Pp curve shapes (half and complete inverse curve) depending on the level of stress reached by the trees.
There was a tight correlation between the hourly spot measurements of ψs and gs with the probe data.
Overall, results show that the ZIM-probe enables the detection of drought stress in clementine and persimmon trees.
Nevertheless, different approaches for calculating the water stress level must be used in each of these species due to the higher tendency of persimmon leaves to the inversed Pp curve phenomena.
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