Diurnal Cycle Relationships between Passive Fluorescence, PRI and NPQ of Vegetation in a Controlled Stress Experiment

Alonso, Luis; Wittenberghe, Shari Van; Amorós-López, Julia; Vila‐Francés, Joan; Gómez-Chova, Luis; Moreno, José

doi:10.3390/rs9080770

Cited by 73 publications

(48 citation statements)

References 31 publications

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“…Airborne imaging spectroscopy data acquired before noon, and after correction the spectral composition of light incident on sunlit and shaded foliage, contained no difference in sunlit and shaded needle PRI. Indeed, according to the measurements reported here, a PRI gradient with PPFD is only expected to develop at around noon in a boreal conifer forest, contrary to what has been reported for other species (e.g., [19]). To apply the correction for the spectral composition of incident light, at least the amount of sunlit foliage in the field of view of the sensor is required [42] and, preferably, also the dependence of PRI on this fraction [22,43].…”

Section: Discussioncontrasting

confidence: 84%

“…The diurnal cycle of PRI is likely to be different for different species growing in different climatic conditions. An alternative would be to study this phenomenon under controlled conditions (following Alonso et al [19]), but this is difficult for fully-grown trees and would inevitably exclude some environmental factors.…”

Section: Discussionmentioning

confidence: 99%

“…The link between PRI and LUE, therefore, provides an opportunity to improve the mapping of carbon sequestration by vegetation from remote sensing data. The processes involved are extensively documented in the literature and the reader is referred to Garbulsky et al [7] and Alonso et al [19].…”

Section: Introductionmentioning

confidence: 99%

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Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

et al. 2018

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Abstract:The photochemical reflectance index (PRI) is calculated from vegetation narrowband reflectance in two bands in the visible part of the spectrum. Variations in PRI are associated with changes in the xanthophyll cycle pigments which regulate the light use efficiency of vegetation. Correlations have been found between remotely-sensed PRI and various photosynthetic productivity parameters at the scales from leaves to landscapes. Environmental satellites can provide only an instantaneous value of this index at the time of overpass. The diurnal course of needle (leaf) PRI needs to be known in order to link the instantaneous values robustly with photosynthetic parameters at time scales exceeding one day. This information is not currently available in the scientific literature. Here we present the daily cycle of Scots pine needle and canopy PRI in a southern boreal forest zone in the presence of direct solar radiation during the peak growing season of two consecutive years. We found the PRI of the needles which are exposed to direct radiation to have a distinct diurnal cycle with constant or slightly increasing values before noon and a daily minimum in the afternoon. The cycle in needle PRI was not correlated with that in the incident photosynthetic photon flux density (PPFD). However, when PPFD was above 1000 µmol m −2 s −1 , approximately between 8 a.m. and 5 p.m., needle PRI was correlated with the light use efficiency (LUE), measured with shoot chambers. The timing of the minimum needle PRI coincided with the minimum canopy value, as measured by an independent sensor above the canopy, but the correlation between the two variables was not significant. Our field results corroborate the applicability of needle PRI in monitoring the daily variation in LUE. However, to apply this to remote sensing of seasonal photosynthetic productivity, the daily cycle of leaf PRI needs to be known for the specific vegetation type.

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Section: Discussioncontrasting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

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Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

et al. 2018

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“…Although the local sunrise was at about 6 o'clock, we found that PRI remains stable until 8:00. Thus, in this research, we used the PRI value in the early morning at 8:00. as PRI 0 because the absorbed energy is still efficiently trapped for photosynthesis during the early morning and photoprotection is not activated [25]. Therefore, in the study, ∆PRI was calculated using Equation (6) to reflect the diurnal effects of the xanthophyll cycle.…”

Section: Calculations Of Sif Sif Yield and Primentioning

confidence: 99%

Diurnal Response of Sun-Induced Fluorescence and PRI to Water Stress in Maize Using a Near-Surface Remote Sensing Platform

Liu

Zhao

et al. 2018

Remote Sensing

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Sun-induced Fluorescence (SIF) and Photochemical Reflectance Index (PRI) data were collected in the field over maize to study their diurnal responses to different water stresses at the canopy scale. An automated field spectroscopy system was used to obtain continuous and long-term measurements of maize canopy in four field plots with different irrigation treatments. This system collects visible to near-infrared spectra with a spectrometer, which provides a sub-nanometer spectral resolution in the spectral range of 480~850 nm. The red SIF (FR) and far red SIF (FFR) data were retrieved by Spectral Fitting Methods (SFM) in the O 2 -A band and O 2 -B band, respectively. In addition to PRI, Δ PRI values were derived from PRI by subtracting an early morning PRI value. Photosynthetic active radiation (PAR) data, the canopy fraction of absorbed PAR (fPAR), and the air/canopy temperature and photosystem II operating efficiency (YII) at the leaf scale were collected concurrently. In this paper, the diurnal dynamics of each parameter before and after watering at the jointing stage were compared. The results showed that (i) both FR and FFR decreased under water stress, but FR always peaked at noon, and the peak of FFR advanced with the increase in stress. Leaf folding and the increase in Non-photochemical Quenching (NPQ) are the main reasons for this trend. Leaf YII gradually decreased from 8:00 to 14:00 and then recovered. In drought, leaf YII was smaller and decreased more rapidly. Therefore, the fluorescence yield at both the leaf and canopy scale responded to water stress. (ii) As good indicators of changes in NPQ, diurnal PRI and Δ PRI data also showed specific decreases due to water stress. Δ PRI can eliminate the impact of canopy structure. Under water stress, Δ PRI decreased rapidly from 8:00 to 13:00, and the maximum range of this decrease was approximately 0.05. After 13:00, their values started to increase but could not recover to their morning level. (iii) Higher canopy-air temperature differences ( Δ T ) indicate that stomatal closure leads to an increase in leaf temperature, which maintains a higher state in the afternoon. In summary, to cope with water stress, both leaf folding and changes in physiology are activated. To monitor drought, SIF performs best around midday, and PRI is better after noon.

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“…Heat and water stress have been proven to affect photorespiration, but not the PQ in Mediterranean species [34], thus decoupling photochemistry from F 760 [18]. Ts, in particular, contains information on both the activation of NPQ mechanisms and other processes related to stomatal closure and sensible heat losses [35]. Therefore, surface temperature might also help to better characterize the seasonal variations of LUE p and therefore to better predict GPP, in particular under stress conditions [35,36].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen and Phosphorus Effect on Sun-Induced Fluorescence and Gross Primary Productivity in Mediterranean Grassland

et al. 2019

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Sun-Induced fluorescence at 760 nm (F760) is increasingly being used to predict gross primary production (GPP) through light use efficiency (LUE) modeling, even though the mechanistic processes that link the two are not well understood. We analyzed the effect of nitrogen (N) and phosphorous (P) availability on the processes that link GPP and F760 in a Mediterranean grassland manipulated with nutrient addition. To do so, we used a combination of process-based modeling with Soil-Canopy Observation of Photosynthesis and Energy (SCOPE), and statistical analyses such as path modeling. With this study, we uncover the mechanisms that link the fertilization-driven changes in canopy nitrogen concentration (N%) to the observed changes in F760 and GPP. N addition changed plant community structure and increased canopy chlorophyll content, which jointly led to changes in photosynthetic active radiation (APAR), ultimately affecting both GPP and F760. Changes in the abundance of graminoids, (%graminoids) driven by N addition led to changes in structural properties of the canopy such as leaf angle distribution, that ultimately influenced observed F760 by controlling the escape probability of F760 (Fesc). In particular, we found a change in GPP–F760 relationship between the first and the second year of the experiment that was largely driven by the effect of plant type composition on Fesc, whose best predictor is %graminoids. The P addition led to a statistically significant increase on light use efficiency of fluorescence emission (LUEf), in particular in plots also with N addition, consistent with leaf level studies. The N addition induced changes in the biophysical properties of the canopy that led to a trade-off between surface temperature (Ts), which decreased, and F760 at leaf scale (F760leaf,fw), which increased. We found that Ts is an important predictor of the light use efficiency of photosynthesis, indicating the importance of Ts in LUE modeling approaches to predict GPP.

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Diurnal Cycle Relationships between Passive Fluorescence, PRI and NPQ of Vegetation in a Controlled Stress Experiment

Cited by 73 publications

References 31 publications

Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

Diurnal Response of Sun-Induced Fluorescence and PRI to Water Stress in Maize Using a Near-Surface Remote Sensing Platform

Nitrogen and Phosphorus Effect on Sun-Induced Fluorescence and Gross Primary Productivity in Mediterranean Grassland

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