Estimating photosynthetic light-use efficiency using the photochemical reflectance index: variations among species

Guo, Jianmin; Trotter, C. M.

doi:10.1071/fp03185

Cited by 92 publications

(69 citation statements)

References 58 publications

(67 reference statements)

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“…But these studies did not demonstrate that the correlations result from reflectance changes at the leaf level brought on by changes in leaf xanthophyll cycle pigments. In fact, a number of other studies have demonstrated that variations in PRI at the scale of forest stands can be caused by other factors, for example, variations in foliage chlorophyll-carotenoid pool sizes, viewing and illumination geometry, canopy structure and background reflectance (Barton & North, 2001;Gamon et al, 2001;Guo & Trotter 2004;Nichol et al, 2002;Rahman et al, 2001;Sims & Gamon, 2002).…”

Section: Introductionmentioning

confidence: 99%

Multi-angle remote sensing of forest light use efficiency by observing PRI variation with canopy shadow fraction

Hall

Hilker

Coops

et al. 2008

Remote Sensing of Environment

171

124

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A B S T R A C T A R T I C L E I N F OWe show that observed co-variations at sub-hourly time scales between the photochemical reflectance index (PRI) and canopy light use efficiency (LUE) over a Douglas-fir forest result directly from sub-hourly leaf reflectance changes in a 531 nm spectral window roughly 50 nm wide. We conclude then, that over a forest stand we are observing the direct effects of photosynthetic down-regulation on leaf-level reflectance at 531 nm. Key to our conclusion is our ability to simultaneously measure the LUE and reflectance of the Douglas-fir stand as a function of shadow fraction from the "hot spot" to the "dark spot" and a new finding herein, based on radiative transfer theory, that the magnitude of a normalized reflectance difference index (NDRI) such as PRI can vary with shadow fraction only in case the reflectance of the shaded and sunlit leaves differ in at least one of the NDRI bands. Our spectrometer measurements over a nearly 6 month period show that at a forest stand scale, only two NDRIs (both containing a band near 570 nm) vary with shadow fraction and are correlated with LUE; an NDRI with a band centered at 531 nm roughly 50 nm wide, and another near 705 nm. Therefore, we are able to conclude that only these two bands' reflectance differ between the sunlit and the shaded elements of the canopy. Their reflectance changes on time scales of a few minutes or less. Our observations also show that the reflectance changes at 531 nm are more highly correlated with variations in canopy light use efficiency when only sunlit canopy elements are viewed (the hot spot), than when only shaded elements (the dark spot) are viewed. Taken together then, these results demonstrate that the observed sub-hourly changes in foliage reflectance at 531 nm and 705 nm can only result from corresponding variations in photosynthetic rates. The importance of our results are as follows: (1) We show that variations in PRI with LUE are a direct result of rapid changes in foliage reflectance at 531 nm resulting from photosynthetic down-regulation, and can be observed at forest scales. (2) Our findings also suggest a new sensor and methodology for the direct retrieval from space of changes in forest LUE by measuring PRI as a function of shadow fraction using a multi-angle spectrometer simultaneously retrieving both shadow fraction and PRI.

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Section: Introductionmentioning

confidence: 99%

Multi-angle remote sensing of forest light use efficiency by observing PRI variation with canopy shadow fraction

Hall

Hilker

Coops

et al. 2008

Remote Sensing of Environment

171

124

View full text Add to dashboard Cite

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“…In addition, the PRI is an index that was first formulated as an indicator of photosynthetic efficiency, but is also an indicator of photosynthesis rate through light use efficiency (Asner et al, 2005;Drolet et al, 2005;Fuentes et al, 2006;Guo & Trotter, 2004;Nakaji et al, 2006;Nichol et al, 2000Nichol et al, , 2002Serrano & Peñuelas, 2005;Sims et al, 2006;Strachan et al, 2002;Trotter et al, 2002) and through chlorophyll fluorescence (Dobrowsky et al, 2005;Evain et al, 2004;Nichol et al, 2006). Therefore, PRI in addition to being a water stress indicator, is also directly related to several physiological processes involved in the photosynthetic system.…”

Section: Introductionmentioning

confidence: 99%

Detecting water stress effects on fruit quality in orchards with time-series PRI airborne imagery

Suárez

Zarco‐Tejada

González-Dugo

et al. 2010

Remote Sensing of Environment

120

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A methodology for the assessment of fruit quality in crops subjected to different irrigation regimes is presented. High spatial resolution multispectral and thermal airborne imagery were used to monitor crown temperature and the Photochemical Reflectance Index (PRI) over three commercial orchards comprising peach, nectarine and orange fruit trees during 2008. Irrigation regimes included sustained and regulated deficit irrigation strategies, leading to high variability of fruit quality at harvest. Stem water potential was used to monitor individual tree water status on each study site. Leaf samples were collected for destructive sampling of xanthophyll pigments to assess the relationship between the xanthophyll epoxidation state (EPS) and PRI at leaf and airborne-canopy level. At harvest, fruit size, Total Soluble Solids (TSS) and Tritatable Acidity (TA) were measured to characterize fruit quality. A statistically significant relationship between EPS and PRI was found at the leaf (r 2 = 0.81) and canopy level (r 2 = 0.41). Airborne-derived crown PRI calculated from the imagery acquired during the fruit growth was related to the ratio of the total soluble solids normalized by the tritatable acidity (TSS/TA), an indicator of fruit quality measured on the same trees, yielding a coefficient of determination of r 2 = 0.50. The relationship between the integral of PRI time-series and TSS/TA yielded a coefficient of determination of r 2 =0.72(peach) and r 2 = 0.61 (nectarines). On the contrary, the relation between TSS/TA and the time-series of crown thermal imagery was very weak (r 2 = 0.21 and 0.25 respectively). These results suggest that a physiological remote sensing indicator related to photosynthesis, such as PRI, is more appropriate for fruit quality assessment than crown temperature, the established method of water stress detection, which is more related to crown transpiration. A radiative transfer modelling study was conducted to assess the potential validity of this methodology for fruit quality assessment when using medium spatial resolution imagery. The analysis shows important effects of soil and shadows on the PRI vs EPS relationship used for fruit quality assessment if non-pure crown reflectance was extracted from the imagery.

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“…As the xanthophyll pigments are related to light absorption mechanisms, the PRI index has been extensively linked to light-use ef fi ciency (LUE) at leaf scale (Guo and Trotter 2004 ;Sims et al 2006 ;Nakaji et al 2006 ) and at canopy scale using fi eld spectrometers (Trotter et al 2002 ;Strachan et al 2002 ;Nichol et al 2000Nichol et al , 2002 and using satellite imagery such as EO-1 Hyperion (Asner et al 2005 ) , MODIS (Drolet et al 2005 ) and AVIRIS (Fuentes et al 2006 ) .…”

Section: Use Of Remote Sensing Data Related To Vegetation Physiologymentioning

confidence: 99%

“…The estimation of LUE through the remote sensing PRI index is demonstrated as a direct link to photosynthesis rate assessment (Nichol et al 2000(Nichol et al , 2006Guo and Trotter 2004 ;Sims et al 2006 ) . In addition, photosynthesis has also been related to PRI through chlorophyll fl uorescence and nonphotochemical quenching (Evain et al 2004 ;Nichol et al 2006 ) .…”

Section: Use Of Remote Sensing Data Related To Vegetation Physiologymentioning

confidence: 99%

Spectral Response of Citrus and Their Application to Nutrient and Water Constraints Diagnosis

Suárez

Berni

2012

Advances in Citrus Nutrition

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The early diagnosis of nutrient and water stress is a key issue for the proper management of orchards. Unfortunately, the measurement of indicators in the fi eld to assess those de fi ciencies is expensive and time consuming. Remote sensing provides the possibility of assessing water and nutrient stress over every single stand on the whole area of interest. Leaf and canopy spectra are affected by every vegetation process or change in leaf pigments. However, the effect of each nutrient de fi ciency on the canopy spectrum is very subtle and the wavelength ranges affected by the different nutrients are generally overlapping. Then, an analysis in detail is needed in order to properly discriminate between the different stress causes. This chapter presents a review of previous studies dealing with remote sensing of nutrient and water stress, de fi ning the spectral regions affected and the methodologies that have been applied for vegetation stress assessment. Speci fi c multispectral indices related to leaf pigment content and physiological vegetation processes, thermal imagery, and fl uorescence studies are presented. Finally, some results obtained from radiative transfer modeling simulations highlight the importance of the spatial resolution for precise agriculture purposes.There is extensive future research needed focusing on dissembling the overlapping effects of different nutrient de fi ciencies on the electromagnetic spectrum. Generally, vegetation indices used for nutrient assessment are affected by more than one nutrient content; a speci fi c diagnosis is dif fi cult to solve. As an example, pertinent indices can be developed in order to perform a proper stress diagnosis. Additionally, leaf-level radiative transfer models can be improved to account for differences in speci fi c pigments. If leaf re fl ectance can be modeled for different nutrient levels, tree nutrient status can be assess through modeling inversion. Modeling inversion techniques are especially interesting because they do not rely on site-speci fi c empirical relationships, being applicable to extensive areas.

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Estimating photosynthetic light-use efficiency using the photochemical reflectance index: variations among species

Cited by 92 publications

References 58 publications

Multi-angle remote sensing of forest light use efficiency by observing PRI variation with canopy shadow fraction

Multi-angle remote sensing of forest light use efficiency by observing PRI variation with canopy shadow fraction

Detecting water stress effects on fruit quality in orchards with time-series PRI airborne imagery

Spectral Response of Citrus and Their Application to Nutrient and Water Constraints Diagnosis

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