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.

Synthesis and characterization of the leaf-like Cu2O/CuO mixed phase nanosheets array

2019 ◽  
Vol 33 (36) ◽  
pp. 1950461 ◽  
Author(s):  
Yan Qi ◽  
Bingqian Bi ◽  
Yilin Yan ◽  
Lecheng Tian
Keyword(s):  
Near Infrared ◽  
Wavelength Region ◽  
Infrared Region ◽  
Mixed Phase ◽  
Synthesis And Characterization ◽  
Average Height ◽  
Xps Analysis ◽  
Sem Images ◽  
Near Infrared Region

In this study, a leaf-like [Formula: see text] mixed phase nanosheets array was successfully prepared by anodization. XRD, EDS, and XPS analysis confirmed the formation of [Formula: see text] mixed phase nanostructures. SEM images indicate that the fabricated [Formula: see text] mixed phase nanosheets almost grow vertically on the substrate. The average height of nanosheets is approximately 500 nm. The optical absorption of the mixed phase covers the entire wavelength region of visible light and a little part of the near-infrared region of short wavelength.

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 Ultrafast transient sub-bandgap absorption of monolayer MoS2

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Susobhan Das ◽  
Yadong Wang ◽  
Yunyun Dai ◽  
Shisheng Li ◽  
Zhipei Sun
Keyword(s):  
Molybdenum Disulfide ◽  
Near Infrared ◽  
Transient Absorption ◽  
Wavelength Region ◽  
Infrared Region ◽  
Short Wavelength Region ◽  
Excited Carrier ◽  
Matter Interaction ◽  
Light Matter Interaction ◽  
Optoelectronic Applications

AbstractThe light–matter interaction in materials is of remarkable interest for various photonic and optoelectronic applications, which is intrinsically determined by the bandgap of the materials involved. To extend the applications beyond the bandgap limit, it is of great significance to study the light–matter interaction below the material bandgap. Here, we report the ultrafast transient absorption of monolayer molybdenum disulfide in its sub-bandgap region from ~0.86 µm to 1.4 µm. Even though this spectral range is below the bandgap, we observe a significant absorbance enhancement up to ~4.2% in the monolayer molybdenum disulfide (comparable to its absorption within the bandgap region) due to pump-induced absorption by the excited carrier states. The different rise times of the transient absorption at different wavelengths indicate the various contributions of the different carrier states (i.e., real carrier states in the short-wavelength region of ~<1 µm, and exciton states in the long wavelength region of ~>1 µm). Our results elucidate the fundamental understanding regarding the optical properties, excited carrier states, and carrier dynamics in the technologically important near-infrared region, which potentially leads to various photonic and optoelectronic applications (e.g., excited-state-based photodetectors and modulators) of two-dimensional materials and their heterostructures beyond their intrinsic bandgap limitations.

scholarly journals First Report of Dothistroma pini, a Recent Agent of the Dothistroma Needle Blight, on Pinus radiata in France

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 841-841 ◽  
Author(s):  
D. Piou ◽  
R. Ioos
Keyword(s):  
Pinus Radiata ◽  
Pcr Analysis ◽  
Host Preferences ◽  
First Report ◽  
The North ◽  
Morphological Studies ◽  
Dothistroma Needle Blight ◽  
Pinus Spp ◽  
Needle Blight ◽  
Pine Species

Dothistroma needle blight (DNB), also known as red band needle blight, is an important fungal disease of Pinus spp. that occurs worldwide. On the basis of molecular and morphological studies of the anamorphic stage, Barnes et al. (1) showed that two closely related species were involved in DNB: Dothistroma septosporum (Dorog.) Morelet and D. pini Hulbary. D. septosporum (teleomorph: Mycosphaerella pini Rostr.) has a worldwide distribution and is reported as the species that caused past epidemics of DNB. This species is reported on more than 80 different pine species, and Pinus radiata D. Don (Monterey pine) is classified as a highly or moderately susceptible species, depending on the published sources (4). D. pini (telemorph: unknown) was initially found on needles of P. nigra J. F. Arnold collected from 1964 to 2001 in the north central United States (Minnesota, Nebraska, and Michigan). It was subsequently found in Ukraine and southwestern Russia, where it has been associated with the emergence of DNB on P. nigra subsp. pallasiana (Lamb.) Holmboe, in Hungary on P. nigra, and in Russia on P. mugo Turra (1). In France, D. pini was reported for the first time on P. nigra, and was sometimes found in association with D. septosporum on the same needles (3). Later on, a more intensive survey of DNB was launched in France and 216 stands of Pinus sp. were studied. D. septosporum and D. pini were detected in 133 and 123 stands, respectively. Both species co-occurred in 40 stands but D. pini was only found on P. nigra (subsp. laricio and austriaca) (2). Up to now, D. pini was therefore only reported on European pine species, mainly on the different allopatric subspecies belonging to the black pine complex and on one occasion on P. mugo, which belongs to the same section and subsection as P. nigra. In March 2011, typical symptoms of DNB (needles with orangey-red brown distal ends, dark red bands, and green bases; small and black fruit bodies within the bands) were observed in a 50- to 60-year old P. radiata stand of ~3 ha located in Pyrénées Atlantiques close to the Spanish border (1°36′08″ W, 43°19′51″ N). The density of pine was relatively low and patches of natural regeneration were present. Although nearly all of the trees showed DNB symptoms, less than 50% of their needles were affected by the disease. In this stand, needles showing typical DNB symptoms were randomly taken from four pines and mixed together to form a single sample for analysis. Total DNA was extracted from symptomatic needle pieces. The presence of D. pini was confirmed by a specific multiplex real-time PCR analysis using the D. pini-specific primers/probe combination DPtef-F1-/R1/-P1 (3), and by sequencing a D. pini-specific amplicon generated by another conventional PCR (3) using DPtef-F/DPtef-R primers (GenBank Accession KC853059) (3). D. septosporum was not detected in the sample. To our knowledge, this is the first report worldwide of D. pini on P. radiata, a pine species largely planted in Spain and in the Southern Hemisphere. This is also the first report of this pathogen on a non-European pine species. The original native range and the host range of D. pini remain unknown and there is currently no data about host preferences or aggressiveness on different pine species. References: (1) I. Barnes et al. For. Pathol. 41:361, 2011. (2) B. Fabre et al. Phytopathology 102:47, 2012. (3) R. Ioos et al. Phytopathology 100:105, 2010. (4) M. Watt et al. For. Ecol. Manage. 257:1505, 2009.

Effect of heat treatment on the reflective spectrum of zinc oxide powders

2009 ◽  
Vol 24 (1) ◽  
pp. 19-23 ◽  
Author(s):  
M.M. Mikhailov ◽  
V.V. Neshchimenko ◽  
Chundong Li ◽  
Shiyu He ◽  
Dezhuang Yang
Keyword(s):  
Heat Treatment ◽  
Zinc Oxide ◽  
Spectral Reflectance ◽  
Near Infrared ◽  
Thermal Control ◽  
Infrared Region ◽  
Light Spectrum ◽  
Absorption Bands ◽  
Oxide Powders ◽  
Reflective Spectrum

To determine the optimum baking temperatures for nanopowder introduction, the variation of reflective spectrum of baked zinc oxide powders, which are used as pigments for thermal control coatings of spacecraft, has been investigated over the wavelength range of 0.225–2.5 μm after being baked at temperatures between 400 °C and 850 °C. It has been established that baking temperatures over 750 °C result in a reduction of spectral reflectance in the visible light spectrum region. This is due to the formation of absorption bands of intrinsic point defects and thus increasing the spectral reflectance in the near-infrared region. The optimum temperature is 650 °C at which the bleaching effect was observed long after heat treatment. Moreover, an increase in the reflection coefficient occurs in the regions of 380–450 nm and 1100–2500 nm in this case.

scholarly journals Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra

2020 ◽  
Vol 492 (4) ◽  
pp. 5470-5507
Author(s):  
E Marfil ◽  
H M Tabernero ◽  
D Montes ◽  
J A Caballero ◽  
M G Soto ◽  
...  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Wavelength Region ◽  
Infrared Region ◽  
High Signal ◽  
Atmospheric Parameters ◽  
Infrared Wavelength ◽  
The Impact ◽  
Higher Sensitivity

ABSTRACT With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double-channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar atmospheric parameters (Teff, log g, ξ, and [Fe/H]) by means of the stepar code, a python implementation of the equivalent width method that employs the 2017 version of the moog code and a grid of MARCS model atmospheres. We compiled four Fe i and Fe ii line lists suited to metal-rich dwarfs, metal-poor dwarfs, metal-rich giants, and metal-poor giants that cover the wavelength range from 5300 to 17 100 Å, thus substantially increasing the number of identified Fe i and Fe ii lines up to 653 and 23, respectively. We examined the impact of the near-infrared Fe i and Fe ii lines upon our parameter determinations after an exhaustive literature search, placing special emphasis on the 14 Gaia benchmark stars contained in our sample. Even though our parameter determinations remain in good agreement with the literature values, the increase in the number of Fe i and Fe ii lines when the near-infrared region is taken into account reveals a deeper Teff scale that might stem from a higher sensitivity of the near-infrared lines to Teff.

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