Articles
Chlorophyll fluorescence imaging as a tool for identifying low-oxygen in apples (Malus x domestica Borkh.)
Article number
1456_9
Pages
67 – 74
Language
English
Abstract
For years, non-imaging chlorophyll fluorescence sensors have been used in the dynamic controlled atmosphere (DCA) storage of apples (Malus × domestica Borkh.). By measuring the minimum fluorescence (Fo) and simultaneously monitoring the oxygen level in the storage room, the lower oxygen limit (LOL) can be identified.
The objective of this study was to record the chlorophyll fluorescence on intact individual ‘Elstar’ apples (n=5) at low-oxygen levels using a fluorescence imaging system (Open FluorCAM 701 MF, Photon Systems Instruments, Brno, Czech Republic). Orange-red light (
max=621 nm; 0.1 μmol m‑2 s‑1) and white saturating light (420-650 nm; max. 1000 μmol m‑2 s‑1) were used to excite the chlorophyll fluorescence and a far-red filter (695-770 nm) was installed in front of the CCD camera.
The experiments were carried out at a storage room temperature ranging from 2 to 2.5°C. The results showed that Fo (arbitrary units) ranges from 180 (MIN) to 257 (MAX) with an average of 226 (±6) under regular air.
Under low oxygen levels, Fo of 528 (±52) was measured.
However, the fluorescence images showed that Fo does not increase evenly across the apple skin.
Fluorescence imaging enabled the spatial distribution of fluorescence to be displayed, providing information on the sample’s fluorescence heterogeneity.
The maximum photosystem II quantum yield (Fv/Fm) was 0.85 (±0.01) under regular air, while Fv/Fm decreased to 0.63 (±0.03) under low-oxygen conditions.
The results show that fluorescence imaging can be a powerful tool for identifying low-oxygen levels on individual apples.
Further research should extend the measurement to a group of apples in a fruit box.
The objective of this study was to record the chlorophyll fluorescence on intact individual ‘Elstar’ apples (n=5) at low-oxygen levels using a fluorescence imaging system (Open FluorCAM 701 MF, Photon Systems Instruments, Brno, Czech Republic). Orange-red light (
max=621 nm; 0.1 μmol m‑2 s‑1) and white saturating light (420-650 nm; max. 1000 μmol m‑2 s‑1) were used to excite the chlorophyll fluorescence and a far-red filter (695-770 nm) was installed in front of the CCD camera.The experiments were carried out at a storage room temperature ranging from 2 to 2.5°C. The results showed that Fo (arbitrary units) ranges from 180 (MIN) to 257 (MAX) with an average of 226 (±6) under regular air.
Under low oxygen levels, Fo of 528 (±52) was measured.
However, the fluorescence images showed that Fo does not increase evenly across the apple skin.
Fluorescence imaging enabled the spatial distribution of fluorescence to be displayed, providing information on the sample’s fluorescence heterogeneity.
The maximum photosystem II quantum yield (Fv/Fm) was 0.85 (±0.01) under regular air, while Fv/Fm decreased to 0.63 (±0.03) under low-oxygen conditions.
The results show that fluorescence imaging can be a powerful tool for identifying low-oxygen levels on individual apples.
Further research should extend the measurement to a group of apples in a fruit box.
Authors
T.-P. Schlie, W. Dierend, D. Köpcke, T. Rath
Keywords
dynamic controlled atmosphere, ‘Elstar’, minimum fluorescence, open FluorCAM, storage
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