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Title: Prospects for studying plant water relations using THz technology
Author: Zafiropoulos, Apostolos
ISNI:       0000 0004 2672 1607
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2008
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Taking into consideration tlie current understanding of the biophysical processes encountered in plants, expressions for the water potential at the cellular and tissue level as well as in the immediate environment around a canopy have been clarified. A critical review of the different THz technologies is provided and conclusions are made on the suitability of different measurement systems for noninvasively monitoring the water status of plants. Broadband spectrometric measurements of leafwater content are provided to demonstrate the advantage of operating at this part of the spectrum. Elaborate null-balance bridge techniques are discussed in detail as these can provide a measure of absolute reflectance or transmittance from the sample. A discussion of an automated (microprocessor based) procedure for finding the nulls corresponding to a balanced state of the instrument is provided. The performance limits of the automated reflectometer are discussed by performing measurements on several samples spanning the entire range of possible reflectivities. The errors from the balancing procedure are propagated to the leaf water content index so as to establish the levels of performance required for such instrument to be useful to plant scientists. Additional errors related to this balancing procedure due to the diffractive spreading of the beam in the sample arm of the interfermeter before reported in the literature are provided. Furthermore, a new leaf-water-content index is suggested as a way of relating leaf relative water content to THz reflectance directly. It is explained that provided additional equipment is available, the above parameters can provide estimates of leaf water potential, solute or matric potential and volumetric elastic modulus of the cells.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available