A new minimum fluorescence parameter, as generated using pulse frequency modulation, compared with pulse amplitude modulation: F α versus F o

Wright, A. Harrison; DeLong, John M.; Franklin, Jeffrey L.; Lada, Rajasekaran R.; Prange, Robert K.

doi:10.1007/s11120-008-9313-2

Cited by 10 publications

(10 citation statements)

References 11 publications

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“…The photosynthetic activity of the microalgae was measured using the pulsed amplitude modulation (PAM) method with a Handy PEA (Hansatech instruments) fluorometer. This method uses the saturation pulse method, in which a phytoplankton sample is subjected to a short beam of light that saturates the photosystem II (PS II) reaction centers of the active chlorophyll molecules. − This process suppresses photochemical quenching, which might otherwise reduce the maximum fluorescence yield. A ratio of variable over maximal fluorescence (Fv/Fm) can then be calculated which approximates the potential quantum yield of PS II.…”

Section: Methodsmentioning

confidence: 99%

Photosynthetic Microorganism-Mediated Synthesis of Akaganeite (β-FeOOH) Nanorods

et al. 2009

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Common Anabaena and Calothrix cyanobacteria and Klebsormidium green algae are shown to form intracellularly akaganeite beta-FeOOH nanorods of well-controlled size and unusual morphology at room temperature. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy X-ray energy dispersive spectrometry (SEM-EDS) analyses are used to investigate particle structure, size, and morphology. A mechanism involving iron-siderophore complex formation is proposed and compared with iron biomineralization in magnetotactic bacteria.

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Section: Methodsmentioning

confidence: 99%

Photosynthetic Microorganism-Mediated Synthesis of Akaganeite (β-FeOOH) Nanorods

et al. 2009

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“…Healthy, mature leaves of a similar age and size were selected for each experiment. The darkadapted LOL of the spinach at 20°C, as indicated by an increase in F a (an approximation of F o ) using pulse frequency modulation (PFM) technology (HarvestWatch TM , Satlantic Inc., Halifax, NS, Canada) (Wright et al 2008), was &0.50 kPa O 2 (n = 8) (data not shown). 1 For the purposes of this article, O 2 levels below 0.5 kPa will be described as anoxic, while those below normoxia (20.9 kPa), but above 0.5 kPa will be referred to as hypoxic.…”

Section: Plant Materialsmentioning

confidence: 99%

“…When O 2 levels are above the LOL, F o remains relatively unchanged; however, when O 2 levels drop below the LOL, F o increases greatly (Wright et al 2010). When O 2 levels are adjusted back above the LOL, F o returns to pre-stress levels (Prange et al 2003;Wright et al 2008Wright et al , 2010. The increase in F o in response to low-O 2 stress correlates with respiratory changes and so yields comparable LOLs (Gasser et al 2008(Gasser et al , 2010; Online Resource 1).…”

Section: Introductionmentioning

confidence: 98%

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The interrelationship between the lower oxygen limit, chlorophyll fluorescence and the xanthophyll cycle in plants

et al. 2011

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The lower oxygen limit (LOL) in plants may be identified through the measure of respiratory gases [i.e. the anaerobic compensation point (ACP) or the respiratory quotient breakpoint (RQB)], but recent work shows it may also be identified by a sudden rise in dark minimum fluorescence (F(o)). The interrelationship between aerobic respiration and fermentative metabolism, which occur in the mitochondria and cytosol, respectively, and fluorescence, which emanates from the chloroplasts, is not well documented in the literature. Using spinach (Spinacia oleracea), this study showed that F(o) and photochemical quenching (q(P)) remained relatively unchanged until O(2) levels dropped below the LOL. An over-reduction of the plastoquinone (PQ) pool is believed to increase F(o) under dark + anoxic conditions. It is proposed that excess cytosolic reductant due to inhibition of the mitochondria's cytochrome oxidase under low-O(2), may be the primary reductant source. The maximum fluorescence (F(m)) is largely unaffected by low-O(2) in the dark, but was severely quenched, mirroring changes to the xanthophyll de-epoxidation state (DEPS), under even low-intensity light (≈4 μmol m(-2) s(-1)). In low light, the low-O(2)-induced increase in F(o) was also quenched, likely by non-photochemical and photochemical means. The degree of quenching in the light was negatively correlated with the level of ethanol fermentation in the dark. A discussion detailing the possible roles of cyclic electron flow, the xanthophyll cycle, chlororespiration and a pathway we termed 'chlorofermentation' were used to interpret fluorescence phenomena of both spinach and apple (Malus domestica) over a range of atmospheric conditions under both dark and low-light.

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“…Tim-Pascal Schlie Tim-Pascal.Schlie@hs-osnabrueck.de 1 Faculty of Agricultural Sciences and Landscape Architecture, Hochschule Osnabrück-University of Applied Sciences, Oldenburger Landstraße 24, 49090 Osnabrück, Germany 2 Chamber of Agriculture Lower Saxony, Fruit Research Center Jork, Moorende 53, 21635 Jork, Germany close to the lower oxygen limit (LOL). The LOL represents the oxygen level that is still tolerated by the apple without developing disorders of fermentation (Prange et al 2002;Wright et al 2008Wright et al , 2012. One option to monitor the fruit's fermentation behavior is the measurement of chlorophyll fluorescence (Prange et al 2002;Wright et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The Impact of Fruit Ripeness on the Lower Oxygen Limit, Chlorophyll Fluorescence and Fermentation Behavior in Apples

et al. 2023

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Dynamic Controlled Atmosphere-Chlorophyll Fluorescence storage (DCA-CF) uses a fluorescence-based measurement method to detect fermentation in apples (Malus × domestica BORKH.) caused by low-oxygen levels at an early stage. In recent years, it has been observed that individual apples of the same variety and origin can exhibit different fermentation behavior when stored under completely identical conditions. The causes of the different fermentation behavior must be found in order to be able to use DCA storage optimally. This study aimed to find the causes of the different fermentation behaviors of individual apples. Our results show that fruit ripeness can affect the lower oxygen limit (LOL), especially immediately after harvest, when the starch degradation in the fruit is not yet complete. A significant increase in the LOL was observed in ‘Elstar’ (2020: 0.3 kPa, 0.6 kPa, 0.9 kPa; 2021: 0.3 kPa, 0.4 kPa, 0.6 kPa). ‘Braeburn’ also exhibited this behavior regarding the LOL at a lower level. The LOL could not be identified for some of the fruit (varying from 12.5% to 41.7% of the examined apples) previously stored in Ultra Low Oxygen (ULO) storage for 4 months. Also, the chlorophyll content in the apple skin influences the fluorescence measurement method. Within 2 weeks, the chlorophyll content in the apple skin was halved. If the chlorophyll content drops, the reliability of the fluorescence measurement also decreases. It turned out that apples with an Fv/Fm < 0.7 were unsuitable for valid LOL identification.

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A new minimum fluorescence parameter, as generated using pulse frequency modulation, compared with pulse amplitude modulation: F α versus F o

Cited by 10 publications

References 11 publications

Photosynthetic Microorganism-Mediated Synthesis of Akaganeite (β-FeOOH) Nanorods

Photosynthetic Microorganism-Mediated Synthesis of Akaganeite (β-FeOOH) Nanorods

The interrelationship between the lower oxygen limit, chlorophyll fluorescence and the xanthophyll cycle in plants

The Impact of Fruit Ripeness on the Lower Oxygen Limit, Chlorophyll Fluorescence and Fermentation Behavior in Apples

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