scholarly journals Unravelling the physical and physiological basis for the solar-induced chlorophyll fluorescence and photosynthesis relationship

2020 ◽  
Author(s):  
Peiqi Yang ◽  
Christiaan Van der Tol ◽  
Petya K. E. Campbell ◽  
Elizabeth M. Middleton
Keyword(s):  
Chlorophyll Fluorescence ◽  
Heat Dissipation ◽  
Gross Primary Production ◽  
Fluorescence Emission ◽  
Energy Partitioning ◽  
Thermal Dissipation ◽  
Functional Link ◽  
Physiological Basis ◽  
Fluorescence Measurements ◽  
Leaf Level

Abstract. Estimates of the gross terrestrial carbon uptake exhibit large uncertainties. Sun-induced chlorophyll fluorescence (SIF) has an apparent near-linear relationship with gross primary production (GPP). This relationship will potentially facilitate the monitoring of photosynthesis from space. However, the exact mechanistic connection between SIF and GPP is still not clear. To explore the physical and physiological basis for their relationship, we used a unique dataset comprising continuous field measurements of leaf and canopy fluorescence and photosynthesis of corn over a growing season. We found that, at canopy scale, the positive relationship between SIF and GPP was dominated by absorbed photosynthetically active radiation (APAR), which was equally affected by variations in incoming radiation and changes in canopy structure. After statistically controlling these underlying physical effects, the remaining correlation between far-red SIF and GPP due solely to the functional link between fluorescence and photosynthesis at the photochemical level was much weaker. Active leaf-level fluorescence measurements revealed a moderate correlation between the efficiencies of fluorescence emission and photochemistry for sunlit leaves but a weak correlation for shaded leaves. Differentiating sunlit and shaded leaves in the light use efficiency (LUE) models for SIF and GPP facilitates a better understanding of the SIF-GPP relationship at different environmental and canopy conditions. Leaf-level fluorescence measurements also demonstrated that the sustained thermal dissipation efficiency dominated the seasonal energy partitioning while the reversible heat dissipation dominated the diurnal leaf energy partitioning. These diurnal and seasonal variations in heat dissipation underlie, and are thus responsible for, the observed remote sensing-based link between far-red SIF and GPP.  

scholarly journals Unraveling the physical and physiological basis for the solar- induced chlorophyll fluorescence and photosynthesis relationship using continuous leaf and canopy measurements of a corn crop

2021 ◽  
Vol 18 (2) ◽  
pp. 441-465
Author(s):  
Peiqi Yang ◽  
Christiaan van der Tol ◽  
Petya K. E. Campbell ◽  
Elizabeth M. Middleton
Keyword(s):  
Chlorophyll Fluorescence ◽  
Heat Dissipation ◽  
Gross Primary Production ◽  
Energy Partitioning ◽  
Thermal Dissipation ◽  
Data Set ◽  
Functional Link ◽  
Physiological Basis ◽  
Fluorescence Measurements ◽  
Leaf Level

Abstract. Estimates of the gross terrestrial carbon uptake exhibit large uncertainties. Sun-induced chlorophyll fluorescence (SIF) has an apparent near-linear relationship with gross primary production (GPP). This relationship will potentially facilitate the monitoring of photosynthesis from space. However, the exact mechanistic connection between SIF and GPP is still not clear. To explore the physical and physiological basis for their relationship, we used a unique data set comprising continuous field measurements of leaf and canopy fluorescence and photosynthesis of corn over a growing season. We found that, at canopy scale, the positive relationship between SIF and GPP was dominated by absorbed photosynthetically active radiation (APAR), which was equally affected by variations in incoming radiation and changes in canopy structure. After statistically controlling these underlying physical effects, the remaining correlation between far-red SIF and GPP due solely to the functional link between fluorescence and photosynthesis at the photochemical level was much weaker (ρ=0.30). Active leaf level fluorescence measurements revealed a moderate positive correlation between the efficiencies of fluorescence emission and photochemistry for sunlit leaves in well-illuminated conditions but a weak negative correlation in the low-light condition, which was negligible for shaded leaves. Differentiating sunlit and shaded leaves in the light use efficiency (LUE) models for SIF and GPP facilitates a better understanding of the SIF–GPP relationship at different environmental and canopy conditions. Leaf level fluorescence measurements also demonstrated that the sustained thermal dissipation efficiency dominated the seasonal energy partitioning, while the reversible heat dissipation dominated the diurnal leaf energy partitioning. These diurnal and seasonal variations in heat dissipation underlie, and are thus responsible for, the observed remote-sensing-based link between far-red SIF and GPP.

scholarly journals Modelling sun-induced fluorescence and photosynthesis with a land surface model at local and regional scales in northern Europe

2017 ◽  
Vol 14 (7) ◽  
pp. 1969-1987 ◽  
Author(s):  
Tea Thum ◽  
Sönke Zaehle ◽  
Philipp Köhler ◽  
Tuula Aalto ◽  
Mika Aurela ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Land Surface ◽  
Large Scale ◽  
Model Simulation ◽  
Gross Primary Production ◽  
Regional Scale ◽  
Coniferous Forest ◽  
Flux Measurement ◽  
Surface Model ◽  
Fluorescence Measurements

Abstract. Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potential limitations for its application exist. We implemented a SIF model into the JSBACH LSM and used active leaf-level chlorophyll fluorescence measurements (Chl F) to evaluate the performance of the SIF module at a coniferous forest at Hyytiälä, Finland. We also compared simulated GPP and SIF at four Finnish micrometeorological flux measurement sites to observed GPP as well as to satellite-observed SIF. Finally, we conducted a regional model simulation for the Fenno-Scandinavian region with JSBACH and compared the results to SIF retrievals from the GOME-2 (Global Ozone Monitoring Experiment-2) space-borne spectrometer and to observation-based regional GPP estimates. Both observations and simulations revealed that SIF can be used to estimate GPP at both site and regional scales. At regional scale the model was able to simulate observed SIF averaged over 5 years with r2 of 0.86. The GOME-2-based SIF was a better proxy for GPP than the remotely sensed fAPAR (fraction of absorbed photosynthetic active radiation by vegetation). The observed SIF captured the seasonality of the photosynthesis at site scale and showed feasibility for use in improving of model seasonality at site and regional scale.

Exploring the scattering and reabsorption of chlorophyll fluorescence: implications for remote sensing of photosynthesis

2020 ◽  
Author(s):  
Karolina Sakowska ◽  
Maria Pilar Cendrero-Mateo* ◽  
Christiaan van der Tol ◽  
Marco Celesti ◽  
Giorgio Alberti ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Heat Dissipation ◽  
Structural Parameters ◽  
Vegetation Indices ◽  
Field Measurements ◽  
Photosynthetic Performance ◽  
Photochemical Quenching ◽  
Spectral Vegetation Indices ◽  
Leaf Level ◽  
Scope Model

<p>In recent years, technological progress in high-resolution field spectrometers have enabled the use of alternative tracer for constraining ecosystem-scale photosynthesis, i.e. sun-induced fluorescence (SIF). The principle underlying the use of SIF as a proxy of gross primary productivity (GPP) is based on the fact that the light energy absorbed by chlorophyll molecules can proceed into three different pathways: photochemistry, heat dissipation, and chlorophyll fluorescence. Since these processes directly compete for the same excitation energy, measurements of SIF and non-photochemical quenching (NPQ) are expected to provide information on photosynthetic performance.</p><p>However, SIF signal measured at the leaf level or beyond is affected by several processes, including wavelength dependent scattering and reabsorption, which may need to be considered when linking SIF data and photosynthetic CO<sub>2</sub> assimilation.</p><p>To address this question, we conducted a multi-scale and multi-technique study that considered measurements of photosynthetic (GPP), optical (SIF, reflectance - R and transmittance - T), physiological (NPQ) and biophysical (the amount of absorbed photosynthetically active radiation - APAR) parameters of two soybean varieties: the MinnGold mutant, characterized by significantly reduced chlorophyll content (Chl), and the wild type, non-Chl deficient Eiko. We further used the “Soil-Canopy Observation Photosynthesis and Energy fluxes” (SCOPE) model to investigate the reabsorption and scattering of SIF. The measured leaf R, T and SIF and top-of-the-canopy R were used to retrieve biochemical and structural parameters of both varieties by inversion of the SCOPE model, while its forward mode was used to determine and correct for the scattering and reabsorption of SIF at both leaf and canopy level.</p><p>Our study revealed that despite the large difference in Chl content (the ratio of Chl between MinnGold and Eiko was nearly 1:5), similar leaf and canopy photosynthesis rates were maintained in the Chl‐deficient mutant. This phenomenon was captured neither by traditional spectral vegetation indices related to canopy greenness, nor by SIF measured in-situ. However, the modelling simulations revealed that when correcting for leaf and canopy scattering and reabsorption processes both varieties presented similar SIF yield (SIF/APAR). Furthermore, field measurements showed that APAR and NPQ in MinnGold were lower than in Eiko. This together explains the similar measured GPP and simulated SIF yield between the two varieties, and indicates that interpretation and application of SIF as a GPP tracer requires understanding and quantification of all these processes.</p>

scholarly journals Relation of Chlorophyll Fluorescence Sensitive Reflectance Ratios to Carbon Flux Measurements of Montanne Grassland and Norway Spruce Forest Ecosystems in the Temperate Zone

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Alexander Ač ◽  
Zbyněk Malenovský ◽  
Otmar Urban ◽  
Jan Hanuš ◽  
Martina Zitová ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Norway Spruce ◽  
Forest Ecosystems ◽  
Gross Primary Production ◽  
Imaging Spectroscopy ◽  
Fluorescence Emission ◽  
Net Ecosystem Exchange ◽  
Spruce Forest ◽  
Temporal Dimension ◽  
Norway Spruce Forest

We explored ability of reflectance vegetation indexes (VIs) related to chlorophyll fluorescence emission (, ) and de-epoxidation state of xanthophyll cycle pigments (PRI, calculated as ) to track changes in the CO2assimilation rate and Light Use Efficiency (LUE) in montane grassland and Norway spruce forest ecosystems, both at leaf and also canopy level. VIs were measured at two research plots using a ground-based high spatial/spectral resolution imaging spectroscopy technique. No significant relationship between VIs and leaf light-saturated CO2assimilation () was detected in instantaneous measurements of grassland under steady-state irradiance conditions. Once the temporal dimension and daily irradiance variation were included into the experimental setup, statistically significant changes in VIs related to tested physiological parameters were revealed. ΔPRI and Δ() of grassland plant leaves under dark-to-full sunlight transition in the scale of minutes were significantly related to (). In the daily course, the variation of VIs measured in one-hour intervals correlated well with the variation of Gross Primary Production (GPP), Net Ecosystem Exchange (NEE), and LUE estimated via the eddy-covariance flux tower. Statistical results were weaker in the case of the grassland ecosystem, with the strongest statistical relation of the index with NEE and GPP.

The Effect of Chloramphenicol on Photoinhibition of Photosynthesis and Its Recovery in Intact Kiwifruit (Actinidia deliciosa) Leaves

1993 ◽  
Vol 20 (1) ◽  
pp. 33 ◽  
Author(s):  
DH Greer ◽  
WA Laing ◽  
DJ Woolley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Co2 Exchange ◽  
High Light ◽  
Actinidia Deliciosa ◽  
Thermal Dissipation ◽  
Radiative Energy ◽  
Minor Effect ◽  
Photoinhibition Of Photosynthesis ◽  
Fluorescence Measurements ◽  
Time Courses

Photoinhibition of photosynthesis in kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson] leaves in high light and its subsequent recovery in low light was assessed in the presence of chloramphenicol (CAP), an inhibitor of chloroplast-encoded protein synthesis. Rooted cuttings were grown in a controlled environment at a photosynthetic irradiance of 700 μmol m-2 s-1 and a day/night temperature of 25/20�C. Time-courses of photoinhibition and recovery treatments were followed by measuring CO2 exchange and chlorophyll fluorescence at 77K and 692 nm. CAP both exacerbated photoinhibition and blocked recovery for at least 150 min, especially at high temperatures. The close conformation of these two effects affirm that photoinhibition and recovery occur concomitantly. There was no apparent effect of CAP on the xanthophyll cycle, either during photoinhibition or recovery, indicating that zeaxanthin-mediated non-radiative energy (thermal) dissipation was unaffected by CAP. Because the CAP-induced increase in photoinhibition was not matched by an increase in the ratio of zeaxanthin to violaxanthin and antheraxanthin, the capacity of this photoprotective mechanism was apparently saturated. The primary effect of CAP on chlorophyll fluorescence was to affect Fm, the maximum fluorescence. There was only a minor effect on the initial fluorescence, Fo, during the photoinhibition and recovery treatments. The calculation of the rate constants for non-radiative dissipation (kD) and photochemistry (kp) from the fluorescence measurements indicated that an increase in kD occurred during high-light exposures and this was stimulated by CAP. However, since zeaxanthin was not mediating this, an alternative quencher in kiwifruit leaves, perhaps damaged PSII centres, is proposed. This would be consistent with an increased inactivation of PSII, as indicated by the changes in kp.

scholarly journals Leaf-Level Spectral Fluorescence Measurements: Comparing Methodologies for Broadleaves and Needles

2019 ◽  
Vol 11 (5) ◽  
pp. 532 ◽  
Author(s):  
Paulina Rajewicz ◽  
Jon Atherton ◽  
Luis Alonso ◽  
Albert Porcar-Castell
Keyword(s):  
Chlorophyll Fluorescence ◽  
Spectral Properties ◽  
Correction Method ◽  
Integrating Sphere ◽  
Baseline Correction ◽  
Spectral Bands ◽  
Fluorescence Measurements ◽  
Custom Made ◽  
Leaf Level ◽  
Broadleaf Species

Successful measurements of chlorophyll fluorescence (ChlF) spectral properties (typically in the wavelength range of 650–850 nm) across plant species, environmental conditions, and stress levels are a first step towards establishing a quantitative link between solar-induced chlorophyll fluorescence (SIF), which can only be measured at discrete ChlF spectral bands, and photosynthetic functionality. Despite its importance and significance, the various methodologies for the estimation of leaf-level ChlF spectral properties have not yet been compared, especially when applied to leaves with complex morphology, such as needles. Here we present, to the best of our knowledge, a first comparison of protocols for measuring leaf-level ChlF spectra: a custom-made system designed to measure ChlF spectra at ambient and 77 K temperatures (optical chamber, OC), the widely used FluoWat leaf clip (FW), and an integrating sphere setup (IS). We test the three methods under low-light conditions, across two broadleaf species and one needle-like species. For the conifer, we characterize the effect of needle arrangements: one needle, three needles, and needle mats with as little gap fraction as technically possible. We also introduce a simple baseline correction method to account for non-fluorescence-related contributions to spectral measurements. Baseline correction was found especially useful in recovering the spectra nearby the filter cut-off. Results show that the shape of the leaf-level ChlF spectra remained largely unaffected by the measurement methodology and geometry in OC and FW methods. Substantially smaller red/far-red ratios were observed in the IS method. The comparison of needle arrangements indicated that needle mats could be a practical solution to investigate temporal changes in ChlF spectra of needle-like leaves as they produced more reproducible results and higher signals.

scholarly journals Modelling sun-induced fluorescence and photosynthesis with a land surface model at local and regional scales in northern Europe

2016 ◽  
Author(s):  
Tea Thum ◽  
Sönke Zaehle ◽  
Philipp Köhler ◽  
Tuula Aalto ◽  
Mika Aurela ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Land Surface ◽  
Large Scale ◽  
Model Simulation ◽  
Gross Primary Production ◽  
Coniferous Forest ◽  
Land Surface Model ◽  
Flux Measurement ◽  
Surface Model ◽  
Fluorescence Measurements

Abstract. Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potential limitations for its application exist. We implemented a SIF model into the JSBACH LSM and used active leaf level chlorophyll fluorescence measurements (ChlF) to evaluate the performance of the SIF module at a coniferous forest at Hyytiälä, Finland. We also compared simulated GPP and SIF at four Finnish micrometeorological flux measurement sites to observed GPP as well as to satellite observed SIF. Finally, we conducted a regional model simulation for the Fenno-Scandinavian region with JSBACH and compared the results to SIF retrievals from the GOME-2 (Global Ozone Monitoring Experiment-2) space-borne spectrometer and to observation-based regional GPP estimates. Both observations and simulations revealed that SIF can be used to estimate GPP at both site and regional scales. The GOME-2 based SIF was a better proxy for GPP than the remotely sensed fAPAR (fraction of absorbed photosynthetic active radiation by vegetation), even though high SIF values occurred during early spring at the northern latitudes, although these are not likely to be associated with photosynthesis.

Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 541a-541
Author(s):  
Lailiang Cheng ◽  
Leslie H. Fuchigami ◽  
Patrick J. Breen
Keyword(s):  
High Light ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Light Conditions ◽  
Psii Efficiency ◽  
Fluorescence Measurements ◽  
Free Radical Formation ◽  
Highly Correlated ◽  
Non Photochemical Quenching ◽  
Leaf N

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

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