Non-invasive assessment of leaf water status using a dual-mode microwave resonator.
The water status in plant leaves is a good indicator for the water status in the whole plant revealing stress if the water supply is reduced. The analysis of dynamic aspects of water availability in plant tissues provides useful information for the understanding of the mechanistic basis of drought stress tolerance, which may lead to improved plant breeding and management practices. The determination of the water content in plant tissues during plant development has been a challenge and is currently feasible based on destructive analysis only. We present here the application of a non-invasive quantitative method to determine the volumetric water content of leaves and the ionic conductivity of the leaf juice from non-invasive microwave measurements at two different frequencies by one sensor device. A semi-open microwave cavity loaded with a ceramic dielectric resonator and a metallic lumped-element capacitor- and inductor structure was employed for non-invasive microwave measurements at 150 MHz and 2.4 Gigahertz on potato, maize, canola and wheat leaves. Three leaves detached from each plant were chosen, representing three developmental stages being representative for tissue of various age. Clear correlations between the leaf- induced resonance frequency shifts and changes of the inverse resonator quality factor at 2.4 GHz to the gravimetrically determined drying status of the leaves were found. Moreover, the ionic conductivity of Maize leaves, as determined from the ratio of the inverse quality factor and frequency shift at 150 MHz by use of cavity perturbation theory, was found to be in good agreement with direct measurements on plant juice. In conjunction with a compact battery- powered circuit board- microwave electronic module and a user-friendly software interface, this method enables rapid in-vivo water amount assessment of plants by a handheld device for potential use in the field.
INRES-Plant Breeding, University of Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
Said
S
Dadshani
EMISENS GmbH, Zur Rur 25, 52428 Juelich, Germany.
Andriy
A
Kurakin
INRES-Plant Breeding, University of Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
Shukhrat
S
Amanov
INRES-Plant Breeding, University of Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
Benedikt
B
Hein
EMISENS GmbH, Zur Rur 25, 52428 Juelich, Germany.
Heinz
H
Rongen
EMISENS GmbH, Zur Rur 25, 52428 Juelich, Germany.
Steve
S
Cranstone
EMISENS GmbH, Zur Rur 25, 52428 Juelich, Germany.
Ulrich
U
Blievernicht
Dr.- Ing. Elmar Menzel Ingenieurbüro, Birkenstr. 18, 63533 Mainhausen, Germany.
Elmar
E
Menzel
INRES-Plant Breeding, University of Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
Jens
J
Léon
EMISENS GmbH, Zur Rur 25, 52428 Juelich, Germany ; Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ UK.
Norbert
N
Klein
INRES-Plant Breeding, University of Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
Agim
A
Ballvora
Microwave resonator; Non-invasive measurements; Water content