Spectral reflectance characteristics of eucalypt foliage damaged by insects

2001 ◽  
Vol 49 (6) ◽  
pp. 687 ◽  
Author(s):  
C. Stone ◽  
L. Chisholm ◽  
N. Coops
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Leaf Age ◽  
Electromagnetic Spectrum ◽  
Similar Response ◽  
Leaf Ontogeny ◽  
Maximum Slope ◽  
Mature Leaves ◽  
Eucalypt Species ◽  
Red Coloration

Variables related to foliar damage, leaf morphology, spectral reflectance, chlorophyll fluorescence and chlorophyll content were measured from leaves sampled from mature eucalypts exhibiting symptoms of crown dieback associated with bell miner colonisation located in Olney State Forest, near Wyong, New South Wales. Insect-damaged mature leaves and healthy young expanding leaves of some species exhibited a conspicuous red coloration caused by the presence of anthocyanin pigmentation. For the mature leaves, the level of red coloration was significantly correlated with insect herbivory and leaf necrosis. Significant correlations were also found between the level of red pigmentation and the following four spectral features: maximum reflectance at the green peak (550 nm); the wavelength position and maximum slope of the red edge (690–740 nm) and the maximum reflectance at 750 nm in the near-infrared portion of the electromagnetic spectrum. While it has been shown that anthocyanin pigments are synthesised in some eucalypt species in response to certain abiotic stresses causing photoinhibition and activation of photoprotective mechanisms, this work proposes that biotic agents such as leaf damaging insects and fungal pathogens may induce a similar response in eucalypt foliage resulting in increased levels of anthocyanins. The potential of anthocyanin levels to be related to leaf ontogeny for some eucalypt species was also illustrated in the reflectance spectra. Thus, it is essential that leaf age be considered. This work demonstrates that the identification of a number of key features of leaf spectra can provide a basis for the development of a robust forest health indicator that may be obtained from airborne or spaceborne hyperspectral sensors.

scholarly journals Floral Radiometry: A Biophysical Basis to Characterize Landscapes

2016 ◽  
Author(s):  
R. Jaishanker ◽  
N.P. Sooraj ◽  
M. Somasekheran Pillai ◽  
K. Athira ◽  
Ammini Joseph ◽  
...  
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Flower Color ◽  
Electromagnetic Spectrum ◽  
Ecological Research ◽  
Near Infrared Reflectance ◽  
Early Results ◽  
Representative Species ◽  
Spectrum Characteristic ◽  
Angiosperm Species

AbstractThis paper presents early results on studies of floral spectral reflectance of angiosperms and introduces floral radiometry as an emergent dimension of ecological research in India. Floral spectral reflectance of 121 angiosperm species was measured using hand-held spectroradiometer. The authors describe spectral reflectance of seven representative species within 350-800 nanometer region of the electromagnetic spectrum. Characteristic absorption and reflection of flowers, in ultraviolet and visible regions of the spectrum is reported. Near infrared reflectance was consistently high for all species studied. Flower color is unique to a species and importance of understanding flower color from pollinator’s perspective is highlighted.

scholarly journals Comparable Discrimination of Soil Constituents Using Spectral Reflectance Data (400–1000 nm) Acquired with Hyperspectral Radiometry

Soil Systems ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 45
Author(s):  
Patrick J. Starks ◽  
Ann-Marie Fortuna
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Technical Assistance ◽  
Wavelength Region ◽  
High Signal ◽  
Electromagnetic Spectrum ◽  
Proximal Sensing ◽  
The Impact ◽  
Soil Constituents ◽  
Reflectance Data

Currently, a gap exists in inventorying and monitoring the impact of land use and management on soil resources. Reducing the number of samples required to determine the impact of land management on soil carbon (C) and mineral constituents via proximal sensing techniques such as hyper-spectral radiometry can reduce the cost and personnel required to monitor changes in our natural resource base. Previously, we used an expensive, high signal-to-noise ratio (SNR) field spectrometer to correlate soil constituents to hyperspectral diffuse reflectance (HDR), over the 350–2500 nm (VIS-SWIR) wavelength range. This research is an extension of preceding research but focuses solely on the 400–1000 nm (VIS-NIR) region of the electromagnetic spectrum. This region can be measured using less expensive (albeit with lower SNR), miniaturized, field spectrometers that allow minimal sample preparation. Our objectives are to: (1) further evaluate the use of soil HDR in the visible and near-infrared (VIS-NIR) region acquired using an expensive field hyperspectral spectroradiometer for prediction of soil C and selected fractions and nitrogen (N) constituents, (2) repeat the above measurements using HDR data from samples examined in objective (1) using lower SNR hyperspectral radiometers, and (3) add to the limited literature that addresses determinations of selected soil properties using proximal sensing in the VIS-NIR region. Data analyzed in this study confirms that good to satisfactory prediction equations for soil constituents can be developed from spectral reflectance data within the 400–1000 nm wavelength region obtained using relatively inexpensive field radiometers. This application could reduce the time and resources required to monitor gains or losses in carbon constituents, information that can be used in programing such as Conservation Technical Assistance (CTA), the Conservation Reserve Program (CRP) and Climate-smart agriculture (CSA).

Spectral reflectance characteristics of Pinus radiata needles affected by dothistroma needle blight

2003 ◽  
Vol 81 (6) ◽  
pp. 560-569 ◽  
Author(s):  
Christine Stone ◽  
Laurie A Chisholm ◽  
Simon McDonald
Keyword(s):  
Pinus Radiata ◽  
Spectral Reflectance ◽  
Near Infrared ◽  
Wavelength Region ◽  
Infrared Region ◽  
Diagnostic Features ◽  
Maximum Slope ◽  
Red Edge ◽  
Dothistroma Needle Blight ◽  
Needle Blight

Dothistroma needle blight, caused by Dothistroma septosporum (Dorog) Morelet, is an economically significant disease of several Pinus species in New Zealand, Australia, Chile, South Africa, and parts of Asia, North America, and Europe. The spectral reflectance properties of Pinus radiata D. Don needles infected by D. septosporum were examined over the visible and near-infrared wavelength region (400–1000 nm). The largest reflectance difference occurred on the shoulder of the near-infrared region at 763 nm. Wavelengths of greatest sensitivity to D. septosporum infection were located in the ranges of 675–691 nm, followed by wavelengths near 760 and 550 nm. Sensitivity minima occurred at 434, 493, 506, 709, and 1373 nm. The reflectance ratio best correlated to needle damage was 709/691 nm (r = –0.739, P < 0.001). Among the other reflectance indices tested, an index based on wavelengths of the upper red edge (710–740 nm) was also well correlated (r = –0.730, P < 0.001). There was not a strong linear relationship between the point of maximum slope in the red edge region (red edge position) and needle damage category. This may be because D. septosporum is a necrotrophic fungal pathogen producing a complex series of damage symptoms: initial chlorosis, production of red and brown metabolites, rapid loss of cellular integrity, cell necrosis, and eventual desiccation. Diagnostic features identified in the infected needle spectra may contribute to the formulation of remotely sensed spectral indices for detecting and monitoring dothistroma needle blight in plantations.Key words: Dothistroma, Pinus radiata, needle damage, reflectance spectra, remote sensing.

scholarly journals On the reflectance spectroscopy of snow

2018 ◽  
Author(s):  
Alexander Kokhanovsky ◽  
Maxim Lamare ◽  
Biagio Di Mauro ◽  
Ghislain Picard ◽  
Laurent Arnaud ◽  
...  
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Reflectance Spectroscopy ◽  
System Of Nonlinear Equations ◽  
Electromagnetic Spectrum ◽  
European Alps ◽  
Snow Surface ◽  
Snow Albedo ◽  
Observation Geometry ◽  
Reflectance Measurements

Abstract. We propose a system of analytical equations to retrieve snow grain size and absorption coefficient of pollutants from snow reflectance or snow albedo measurements in the visible and near-infrared regions of the electromagnetic spectrum. It is assumed that ice grains and impurities (e.g., dust, black and brown carbon) are externally mixed. The system of nonlinear equations is solved analytically in the assumption that impurities influence registered spectra in the visible and not at near-infrared (and vice versa for ice grains). The theory is validated using spectral reflectance measurements and albedo of clean and polluted snow at various locations (Antarctica Dome C, European Alps). The technique to derive the snow albedo (plane and spherical) from reflectance measurements at a fixed observation geometry is proposed. The technique also enables the simulation of hyperspectral snow reflectance measurements in the broad spectral range from ultraviolet to the near-infrared for a given snow surface in the case, if the actual measurements are performed at restricted number of wavelengths (2–4, depending on the type of snow and the measurements system).

scholarly journals Metalorganic chemical vapor deposition of InN quantum dots and nanostructures

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Caroline E. Reilly ◽  
Stacia Keller ◽  
Shuji Nakamura ◽  
Steven P. DenBaars
Keyword(s):  
Quantum Dots ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Near Infrared ◽  
Optoelectronic Devices ◽  
Chemical Vapor ◽  
Electromagnetic Spectrum ◽  
Material System ◽  
Metalorganic Chemical

AbstractUsing one material system from the near infrared into the ultraviolet is an attractive goal, and may be achieved with (In,Al,Ga)N. This III-N material system, famous for enabling blue and white solid-state lighting, has been pushing towards longer wavelengths in more recent years. With a bandgap of about 0.7 eV, InN can emit light in the near infrared, potentially overlapping with the part of the electromagnetic spectrum currently dominated by III-As and III-P technology. As has been the case in these other III–V material systems, nanostructures such as quantum dots and quantum dashes provide additional benefits towards optoelectronic devices. In the case of InN, these nanostructures have been in the development stage for some time, with more recent developments allowing for InN quantum dots and dashes to be incorporated into larger device structures. This review will detail the current state of metalorganic chemical vapor deposition of InN nanostructures, focusing on how precursor choices, crystallographic orientation, and other growth parameters affect the deposition. The optical properties of InN nanostructures will also be assessed, with an eye towards the fabrication of optoelectronic devices such as light-emitting diodes, laser diodes, and photodetectors.

scholarly journals Atmospheric Compensation of PRISMA Data by Means of a Learning Based Approach

2021 ◽  
Vol 13 (15) ◽  
pp. 2967
Author(s):  
Nicola Acito ◽  
Marco Diani ◽  
Gregorio Procissi ◽  
Giovanni Corsini
Keyword(s):  
Spectral Range ◽  
Near Infrared ◽  
Random Noise ◽  
Synthetic Data ◽  
Regression Function ◽  
Short Wave ◽  
Hyperspectral Data ◽  
Electromagnetic Spectrum ◽  
Great Opportunity ◽  
Atmospheric Compensation

Atmospheric compensation (AC) allows the retrieval of the reflectance from the measured at-sensor radiance and is a fundamental and critical task for the quantitative exploitation of hyperspectral data. Recently, a learning-based (LB) approach, named LBAC, has been proposed for the AC of airborne hyperspectral data in the visible and near-infrared (VNIR) spectral range. LBAC makes use of a parametric regression function whose parameters are learned by a strategy based on synthetic data that accounts for (1) a physics-based model for the radiative transfer, (2) the variability of the surface reflectance spectra, and (3) the effects of random noise and spectral miscalibration errors. In this work we extend LBAC with respect to two different aspects: (1) the platform for data acquisition and (2) the spectral range covered by the sensor. Particularly, we propose the extension of LBAC to spaceborne hyperspectral sensors operating in the VNIR and short-wave infrared (SWIR) portion of the electromagnetic spectrum. We specifically refer to the sensor of the PRISMA (PRecursore IperSpettrale della Missione Applicativa) mission, and the recent Earth Observation mission of the Italian Space Agency that offers a great opportunity to improve the knowledge on the scientific and commercial applications of spaceborne hyperspectral data. In addition, we introduce a curve fitting-based procedure for the estimation of column water vapor content of the atmosphere that directly exploits the reflectance data provided by LBAC. Results obtained on four different PRISMA hyperspectral images are presented and discussed.

Near-infrared fluorescence imaging with indocyanine green for quantification of changes in tissue perfusion following revascularization

Vascular ◽  
2021 ◽  
pp. 170853812110328
Author(s):  
Pim Van den Hoven ◽  
Floris S Weller ◽  
Merel Van De Bent ◽  
Lauren N Goncalves ◽  
Melissa Ruig ◽  
...  
Keyword(s):  
Indocyanine Green ◽  
Fluorescence Imaging ◽  
Fluorescence Intensity ◽  
Near Infrared ◽  
Tissue Perfusion ◽  
Control Group ◽  
Maximum Slope ◽  
Nir Fluorescence ◽  
Significant Difference ◽  
Revascularization Procedures

Objectives Current diagnostic modalities for patients with peripheral artery disease (PAD) mainly focus on the macrovascular level. For assessment of tissue perfusion, near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) seems promising. In this prospective cohort study, ICG NIR fluorescence imaging was performed pre- and post-revascularization to assess changes in foot perfusion. Methods ICG NIR fluorescence imaging was performed in 36 patients with PAD pre- and post-intervention. After intravenous bolus injection of 0.1 mg/kg ICG, the camera registered the NIR fluorescence intensity over time on the dorsum of the feet for 15 min using the Quest Spectrum Platform®. Time-intensity curves were plotted for three regions of interest (ROI): (1) the dorsum of the foot, (2) the forefoot, and (3) the hallux. Time-intensity curves were normalized for maximum fluorescence intensity. Extracted parameters were the maximum slope, area under the curve (AUC) for the ingress, and the AUC for the egress. The non-treated contralateral leg was used as a control group. Results Successful revascularization was performed in 32 patients. There was a significant increase for the maximum slope and AUC egress in all three ROIs. The most significant difference was seen for the maximum slope in ROI 3 (3.7%/s to 6.6%/s, p < 0.001). In the control group, no significant differences were seen for the maximum slope and AUC egress in all ROIs. Conclusions This study shows the potential of ICG NIR fluorescence imaging in assessing the effect of revascularization procedures on foot perfusion. Future studies should focus on the use of this technique in predicting favorable outcome of revascularization procedures.

The effect of ozone on cottonwood – leaf rust interactions: independence of abiotic stress, genotype, and leaf ontogeny

1987 ◽  
Vol 65 (5) ◽  
pp. 949-953 ◽  
Author(s):  
James S. Coleman ◽  
Clive G. Jones ◽  
William H. Smith
Keyword(s):  
Leaf Rust ◽  
Populus Deltoides ◽  
Leaf Age ◽  
Leaf Length ◽  
Ozone Treatment ◽  
Shoot Biomass ◽  
Leaf Ontogeny ◽  
Leaf Production ◽  
Leaf Injury ◽  
Eastern Cottonwood

The interaction of an acute ozone dose, plant genotype, and leaf ontogeny on the development of cottonwood leaf rust on eastern cottonwood (Populus deltoides Bartr.) was investigated. A rust-resistant (ST 66) and a rust-susceptible (ST 109) clone were exposed to charcoal-filtered air or were fumigated with 393 μg m−3 (0.20 ppm) ozone for 5 h. Forty hours after fumigation, leaf material of different developmental ages was inoculated with urediospores of Melampsora medusae Thum., and uredia production was measured after 10 days. Ozone fumigation of cottonwoods significantly reduced uredia production by M. medusae on both clones and all leaf ages without causing visible leaf injury or measurable changes in cottonwood height growth, leaf production, leaf length, or root/shoot biomass. Uredia production was strongly affected by ozone treatment, cottonwood genotype, and leaf age, but interactions among these three factors did not occur.

scholarly journals Meteorological conditions, ozone concentration and leaf age affect gas exchange in Psidium guajava ‛Palumaʼ

Hoehnea ◽  
2017 ◽  
Vol 44 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Juliana Moreno Pina ◽  
Sérgio Tadeu Meirelles ◽  
Regina Maria de Moraes
Keyword(s):  
Gas Exchange ◽  
Ozone Concentration ◽  
Leaf Age ◽  
Psidium Guajava ◽  
Meteorological Conditions ◽  
Gas Exchanges ◽  
Mature Leaves ◽  
Young Leaves ◽  
Entire Experiment ◽  
The City

ABSTRACT This study aimed to investigate the importance of leaf age, meteorological conditions and ozone concentration (O3) on gas exchange of Psidium guajava ‛Paluma'. Saplings were grown and exposed in standard conditions in the city of São Paulo, in six periods of three months with weekly measurements in young and mature leaves. Gas exchanges were higher in young leaves for almost the entire experiment. Mature leaves showed greater reduction in gas exchange. The multivariate analysis of biotic and abiotic variables indicated that vapor pressure deficit (VPD), O3 concentration and radiation were the main variables associated with gas exchange decrease in young leaves. In mature leaves the influence of VPD is lower, but the temperature importance is higher. Moreover, the opposition between assimilation and O3 is more evident in mature leaves, indicating their greater sensitivity to O3.

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