Kuckenberg, Jan: Early detection and discrimination of biotic and abiotic stresses in Triticum aestivum and Malus domestica by means of chlorophyll fluorescence. - Bonn, 2008. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-14217
@phdthesis{handle:20.500.11811/3250,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-14217,
author = {{Jan Kuckenberg}},
title = {Early detection and discrimination of biotic and abiotic stresses in Triticum aestivum and Malus domestica by means of chlorophyll fluorescence},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2008,
note = {The key objective of this work was to assess the potential of selected chlorophyll fluorescence techniques for detection of temporal and spatial changes in leaf and plant response to economically important stress factors as a basis for implementing these techniques in ‘Precision Farming’.
PAM fluorescence imaging enabled pre-symptomal pathogen detection and visualisation of spatial differences during proceeding Blumeria graminis and Puccinia triticina infections at the individual wheat leaf level. The initial infection of both fungi caused an increase in ground fluorescence (Fo) and a decrease in photochemical efficiency (Fv/Fo, Fv/Fm). Among the evaluated fluorescence parameters, Fv/Fo displayed the most pronounced response to both kinds of infection. However, the detection of pathogen infection appeared less effective if fluorescence images were taken on leaves without previous dark adaptation.
The approach of ‘multipoint’ scanning Laser-Induced Fluorescence (LIF) was applied for detection and discrimination of biotic (leaf rust and powdery mildew) and abiotic (Nitrogen deficiency) stress factors in the light at wheat leaf and canopy level. The results of cross-validation analysis indicated that using this technique, samples with pathogen infections may be miss-recognised as N-deficiency and vice versa. However, considering heterogeneity of fluorescence signals in addition to their mean values significantly improved the identification accuracy of N-deficiency and leaf rust infection at both leaf and canopy level.
In order to avoid misinterpretation of fluorescence signals in ‘Precision Farming’, the effect of enhanced UV-B radiation on LIF and PAM parameters was studied on apple (Malus domestica Borkh.) leaves. Short-term UV-B stress affected neither chlorophyll content nor reflection characteristics of apple leaves, but could be well detected by both fluorescence techniques. Significantly reduced fluorescence intensities and F686/F740 values as well as a high spatial heterogeneity of photosynthetic performance after UV-B stress have to be taken into account for applying these techniques under field conditions. However, the disturbance in photosynthetic functionality was followed by a continuous recovery process as indicated by restoring fluorescence parameters. The rate of recovery was dependent on UV-B dose.
An additional objective of this thesis was to investigate the capability of LIF and light-remission techniques for detecting senescence-induced heterogeneities in apple (cvs ‘Jonagold’ and ‘Golden Delicious’) peel chlorophyll content and internal fruit quality characteristics under shelf life conditions. Changes in ground colour of apple fruit could be successfully monitored by LIF and light-remission techniques, whereas NDVI and fluorescence emission at 730 nm showed the strongest correlation with peel chlorophyll content. The ‘multipoint’ fluorescence scanning mode of LIF technique provided also detailed information on fruit colour heterogeneities. The correlation degree between remission and fluorescence parameters with internal fruit parameters and maturity could be significantly improved by taking into respect differences in pigment content and flesh characteristics on the sunlit and shaded apple sides.},

url = {http://hdl.handle.net/20.500.11811/3250}
}

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