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Chlorophyll Degradation and Formation of Colorless Chlorophyll Derivatives during Soybean (Glycine max L. Merill) Seed Maturation

BORRMANN, Daniela; ANDRADE, Juliana Castelhano de; LANFER-MARQUEZ, Ursula Maria
Fonte: AMER CHEMICAL SOC Publicador: AMER CHEMICAL SOC
Tipo: Artigo de Revista Científica
ENG
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36.93%
The natural chlorophyll degradation results in noncolored chlorophyll catabolites (NCCs), but there are controversies if these are the final products. The formation and degradation of NCCs during soybean seed (Glycine max L. Merrill) maturation and two drying temperatures were investigated. Soybean was harvested at six maturation stages. The effect of postharvest drying at 40 and 60 degrees C on the NCC formation was analyzed by high-performance liquid chromatography (HPLC), and results were expressed as areas under the curve. All samples contained fractions with an absorption maximum at 320 nm, typical for NCC. The amounts of NCC increased until 114 days after planting and were significantly lower in advanced maturation stages. These results indicate that the NCC in soybeans might not be the final products of chlorophyll degradation. Their reduction in advanced maturation stages may be due to further metabolization. Heating soybeans at 40 and 60 degrees C promoted unnatural chlorophyll degradation and impaired the formation of NCC.

Influência da luz e uréia no crescimento e conteúdo de clorofila da biomassa de Spirulina platensis; Influence of light and urea on Spirulina platensis growth and chlorophyll content

Rangel, Carlota de Oliveira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/01/2000 PT
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A microalga Spirulina platensis, fornece uma biomassa rica em proteínas, ácidos graxos polinsaturados, vitaminas e outros componentes de alto valor como a clorofila, a qual pode ser utilizada como corante em medicamentos, cosméticos e alimentos. No presente trabalho, estudou-se a influência da iluminação, simultaneamente com a utilização de uréia como fonte de nitrogênio por meio de processo descontínuo alimentado, no crescimento de Spirulina platensis e conteúdo de clorofila da biomassa. Foram utilizados tanques abertos, com volume de cultivo de 5L. Dentre os ensaios realizados, o melhor crescimento ocorreu com a utilização de 2500mg de uréia a 5600lux de iluminância, e o pior com 2500mg de uréia a 1400lux de iluminância. O maior conteúdo de clorofila na biomassa, por sua vez, foi obtido com 2500mg de uréia a 1400lux de iluminância, e o menor com 2500mg de uréia a 5600lux de iluminância. Uma regressão estatística para a produtividade em clorofila (mg.L-1.dia-1)foi realizada, a partir de valores codificados para os parâmetros em estudo, obtendo-se a seguinte equação de regressão: PCla= 1,53 - O,16.Mutc2 - 0,28.Ec2 + 0,2.Mutc + 0,13.Ec A partir da derivada da equação, calculou-se os valores dos parâmetros estudados correspondentes ao ponto ótimo de produtividade em clorofila para as condições deste trabalho...

Efeito do déficit hídrico em características químicas e bioquímicas da soja e na degradação da clorofila, com ênfase na formação de metabólitos incolores; Influence of drought stress on chemical and biochemical characteristics of soybean and on chlorophyll degradation, with focus on the formation of non-coloured chlorophyll catabolites

Borrmann, Daniela
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/08/2009 PT
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O Brasil é o segundo maior produtor e exportador de soja (Glycine max L. Merrill) no mundo. A produção é altamente dependente de fatores climáticos, incluindo a temperatura e quantidade de chuva. A soja cultivada no sul do país em 2005 sofreu déficit hídrico causado por temperaturas altas acompanhado por umidade baixa durante o estádio reprodutivo. Pouco se sabe sobre a influência do déficit hídrico na degradação da clorofila e na qualidade dos grãos em geral. Nesse trabalho foram analisadas, numa primeira etapa, as características químicas e bioquímicas de cinco amostras de soja, provenientes de três cultivares que cresceram sob déficit hídrico e que não atendiam aos padrões para comercialização por conter altas quantidades de sementes verdes. Os grãos foram analisados quanto a diversos parâmetros físico-químicos e bioquímicos incluindo a análise dos pigmentos verdes imediatamente após a colheita e após 20 meses de armazenamento. A acidez foi medida adicionalmente após 30 meses de armazenamento. A atividade de água e umidade foram 0,6-0,7 e 8,7 %-11,9 %, respectivamente, e não mudaram durante a estocagem, mas houve um aumento em acidez o que indica atividade de lipases. A atividade da lipoxigenase 1 foi significativamente prejudicada. Imediatamente após a colheita os pigmentos verdes correspondiam a feofitina a...

Development of an optimal methodology for the extraction of microphytobenthic chlorophyll

Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, Teresa
Fonte: Universidade do Algarve Publicador: Universidade do Algarve
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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Benthic microalgae are important primary producers in intertidal shallow systems. Their biomass can be estimated by the assessment of chlorophyll a concentration. A rapid and reliable method of measuring chlorophyll a is by spectrophotometer. There is however, no standard protocol for the analysis of benthic chlorophyll a. Although the most common solvent generally used is 90% acetone, some authors showed better results with methanol and ethanol. Some pre-treatments, such as the addition of fine inert granules or ultrasound bath, have also been suggested as factors that improve the extraction efficiency. Sediment samples were collected from two sites, muddy and sandy, located within Ria Formosa (Portugal). The aim of this work was to test the effectiveness of different pre-treatments in the extraction and to develop an optimal method for chlorophyll a extraction and analysis. Pre-treating samples did not yield any significant differences in chlorophyll a extracted. Treating sediments with acetone was found to yield higher concentrations of chlorophyll a, both for muddy and sandy sediments. Acetone was therefore found to be the best solvent for both sediment types, with 90% being the best strength for sandy and 80% the best for muddy sediments. These differences may be related to differences in the structure of the algal communities. Six hours of extraction was found to be sufficient...

SPAD-502 readings in response to photon fluence in leaves with different chlorophyll content

Nascimento,Helena Cristina Santos; Marenco,Ricardo Antonio
Fonte: Universidade Federal de Viçosa Publicador: Universidade Federal de Viçosa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2010 EN
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The chlorophyll meter (SPAD-502) is widely used to estimate chlorophyll content, but non-uniform chloroplast distribution can affect its accuracy. This study aimed to assess the effect of photon fluence (F, irradiance x time of illumination) in leaves with different chlorophyll content and determine the effect of chlorophyll a/b on SPAD values of four tropical tree species (Croton draconoides Müll. Arg., Hevea guianensis Aubl., Hymenaea courbaril L. and Matisia cordata H.B.K.). There were also determined calibration equations for the chlorophyll meter and assessed the effect of F on SPAD values between 07:00 h and 17:00 h. Calibration equations were obtained after determining leaf chlorophyll content in the laboratory. Increases in F with time caused a reduction in SPAD values in species with a high chlorophyll content, with reductions of 20% in M. cordata and 10% in H. guianensis. Leaves of C. draconoides and H. courbaril had lower chlorophyll content and showed no changes in SPAD values with increase in F. The chlorophyll a/b ratio increased with SPAD values and the SPAD/chlorophyll relationship was best described by an exponential equation. It seems that F may affect SPAD values in leaves with high chlorophyll content, probably due to non-uniform chloroplast distribution at high irradiance. This indicates that SPAD values tend to be more accurate if recorded early in morning when irradiance is low.

Chlorophyll fluorescence of the testa of Brassica oleracea seeds as an indicator of seed maturity and seed quality

Jalink,H.; Frandas,A.; Schoor,R. van der; Bino,J.B.
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1998 EN
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Chlorophyll fluorescence of the testa of seeds is proposed as a non-invasive method for the determination of maturity and quality of seeds. In this study cabbage seeds (Brassica oleracea) were sorted individually based on the chlorophyll fluorescence signals into four subsamples labeled with respect to their chlorophyll fluorescence signal (low, medium, high and very high). The results show that the magnitude of the chlorophyll fluorescence signal was inversely related to the quality of the seeds, expressed as germination %, normal seedling %, germination rate (T50) and uniformity of germination (T75-T25). The seed lot could be improved from 90 to 97% normal seedlings by sorting out 13% of the seeds with very high chlorophyll fluorescence signals. Advantages of the chlorophyll fluorescence method for sorting seeds are the high sensitivity, the method being fully non-destructive, the high speed at which the fluorescence is generated and measured and the specificity for only chlorophyll. Other pigments or substances which can influence seed colour but do not fluoresce at the specific wavelengths of excitation and emission of chlorophyll, will not contribute to the fluorescence signal. These characteristics make chlorophyll fluorescence highly suitable as a new sorting technique.

Evaluation of a portable chlorophyll meter to estimate chlorophyll concentrations in leaves of tropical wood species from Amazonian forest

Gonçalves,José Francisco de Carvalho; Santos Junior,Ulysses Moreira dos; Silva,Emerson Alves da
Fonte: Instituto de Botânica Publicador: Instituto de Botânica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2008 EN
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A portable chlorophyll meter can be an important tool to estimating chlorophyll contents in leaves of tree species under field conditions. The method is quick and non-destructive compared to the classic chemical methods of pigment extraction. The aim of this work was to evaluate the performance of a portable chlorophyll meter (CCM-200, Opti-Science) to estimate the concentrations of chloroplastid pigments and the fraction of photosynthetically active irradiance absorbed by leaves (α) in four tropical wood species from Amazonian forest. The results shown positive correlation between the chlorophyll contente index (CCI) readings and concentrations of Chl a (P < 0.0001; r² = 0.904), Chl b (P< 0.0001; r² = 0.803), Chl tot (P< 0.0001; r² = 0.923) and α (P< 0.0001; r² = 0.886), suggesting that the portable chlorophyll meter can be an effective tool for the relative estimation of chlorophyll concentrations and the fraction of the photosynthetically active irradiance absorbed by the leaves of tropical tree species.

Evaluation of SeaWiFS chlorophyll algorithms in the southwestern atlantic and southern oceans

Garcia, Carlos Alberto Eiras; Garcia, Virginia Maria Tavano; McClain, Charles Ray
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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Bio-optical measurements of spectral upwelling radiance and surface chlorophyll-a concentration have been conducted during 15 cruises between 1995 and 2004. The bio-optical data were divided into two sub-sets: the Southwestern Atlantic Ocean (SwAO), comprising a variety of biogeochemical provinces, from the oligotrophic waters in the South Atlantic gyre to the coastal waters influenced by La Plata River and Patos Lagoon discharge, and the Southern Ocean (SO) data set, comprising sampling stations south of the mean position of the Polar Front, with most stations being located in the vicinity of the Antarctic Peninsula. We derived regional chlorophyll algorithms for both regions and comparisons were made with the NASA???s OC4v4 (operational algorithm) and OC2v4. For the Southwestern Atlantic region, the NASA OC4v4 algorithm presented a reasonable performance (r 2=0.87, rmse-L=0.475, N=136) as compared to the revised algorithm for SwAO data (r 2=0.89, rmse-L=0.426, N=136). A few stations under strong river plume influence were not considered in the analyses. These were detected by a higher reflectance at 670 nm, at low in situ chlorophyll concentration (b2 mg m??3). These results show that empirical algorithms applied to in-situ radiance data have a limited ability to extract accurate chlorophyll estimates below a 30% uncertainty level. For Southern Ocean stations...

Variability of chlorophyll-a from ocean color images in the La Plata continental shelf region

Garcia, Carlos Alberto Eiras; Garcia, Virginia Maria Tavano
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.01%
Satellite-derived chlorophyll-a fields have been used to investigate temporal and spatial variability of chlorophyll-a concentration over the continental shelf zone (25???401S and 60???451W) close to the La Plata River estuary. Ocean color data used in this study were obtained by the Sea-viewing Wide Field-of- view Sensor (SeaWiFS) and consisted of 368 weekly averaged Standard Mapped Images (SMI), from October 1997 to September 2005. Fourier harmonic and EOF analyses were used to study the variability of log-transformed chlorophyll-a concentration in the region. The harmonic analysis has shown that the annual cycle was the most dominant signal followed by the semi- and quadri-annual cycles, in certain areas. The strong annual cycle is mainly present in latitudes lower than 341S where relatively high amplitudes ($1.9 mg m??3) in pigment variation are seen over the southern Brazilian continental shelf. The semi-annual cycle is mainly associated with the Brazil???Malvinas frontal zone oscillation while the ?? 4-year signal is related to positive La Plata discharge anomalies influenced by El Nino events. After removing the annual signal from the log-transformed chlorophyll anomalies, the EOF results showed that the first three modes captured 85.1% of the variability associated with the regional mean phytoplankton chlorophyll pattern in our smoothed data set. The first three modes explained...

Understanding phytoplankton variability throughout Spencer Gulf, South Australia, via satellite derived Chlorophyll-A

Bierman, P.; Lewis, M.; Tanner, J.; Ostendorf, B.
Fonte: IEEE; United States Publicador: IEEE; United States
Tipo: Conference paper
Publicado em //2008 EN
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36.98%
MODIS chlorophyll-a imagery was analysed to better understand the dynamics of phytoplankton in Spencer Gulf, South Australia. MODIS chlorophyll-a was validated against in situ chlorophyll-a measurements to assess the performance of MODIS algorithms in this shallow coastal body of water. Monthly mean chlorophyll-a imagery was then used to study the broad-scale seasonal variability in chlorophyll-a throughout Spencer Gulf and surrounding waters. Validation showed a slight overestimation in chlorophyll-a via MODIS when concentrations were low, and also likely coastal influences upon the measurements. The validation was less than conclusive with MODIS measurements explaining just 46% of the variation in the field data. The monthly image sequences identified significant differences in seasonal chlorophyll-a characteristics between different locations within the gulf. Elevated chlorophyll-a concentrations were also observed near the southern bluefin tuna aquaculture zone during winter compared to nearby waters of southern Spencer Gulf.; Paul Bierman, Megan Lewis, Jason Tanner, and Bertram Ostendorf

Vertical distributions of chlorophyll in deep, warm monomictic lakes

Hamilton, D.; O'Brien, K.; Burford, M.; Brookes, J.; McBride, C.
Fonte: Birkhauser Verlag Ag Publicador: Birkhauser Verlag Ag
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
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The factors affecting vertical distributions of chlorophyll fluorescence were examined in four temperate, warm monomictic lakes. Each of the lakes (maximum depth >80 m) was sampled over 2 years at intervals from monthly to seasonal. Profiles were taken of chlorophyll fluorescence (as a proxy for algal biomass), temperature and irradiance, as well as integrated samples from the surface mixed layer for chlorophyll a (chl a) and nutrient concentrations in each lake. Depth profiles of chlorophyll fluorescence were also made along transects of the longest axis of each lake. Chlorophyll fluorescence maxima occurred at depths closely correlated with euphotic depth (r 2 = 0.67, P < 0.01), which varied with nutrient status of the lakes. While seasonal thermal density stratification is a prerequisite for the existence of a deep chlorophyll maximum (DCM), our study provides evidence that the depth of light penetration largely dictates the DCM depth during stratification. Reduction in water clarity through eutrophication can cause a shift in phytoplankton distributions from a DCM in spring or summer to a surface chlorophyll maximum within the surface mixed layer when the depth of the euphotic zone (z eu) is consistently shallower than the depth of the surface mixed layer (z SML). Trophic status has a key role in determining vertical distributions of chlorophyll in the four lakes...

Interannual variation in commercial oyster (Crassostrea gigas) farming in the sea (Florianopolis, Brazil, 27 degrees 44 ' S; 48 degrees 33 ' W) in relation to temperature, chlorophyll a and associated oceanographic conditions

Mizuta, Darien Danielle; Silveira Junior, N.; Fischer, C. E.; Lemos, Daniel Eduardo Lavanholi de
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
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Aquaculture of filter-feeding bivalve mollusks involves the fruitful conversion of marine particulate organic matter into premium protein of high nutritive value. Culture performance of bivalves is largely dependent on hydrological conditions and directly affected by e. g. temperature and chlorophyll levels. Accordingly, these parameters may be related with seasonality but also with oceanographic features combined with climate events. Yields of Pacific cupped oyster (Crassostrea gigas) reared at commercial procedures in suspended structures (long-lines) in a sheltered bay in Southern Brazil (Santa Catarina State, 27S 43'; 48 W 30') were evaluated in relation to local environmental conditions: sea surface temperature, chlorophyll a concentration, and associate effects of cold fronts events and El Nino and La Nina periods. Outputs from four consecutive commercial crop years were analyzed (2005/06, 2006/07, 2007/08, 2008/09) in terms of oyster survival and development time during the following grow-out phases of the culture cycle: seed to juvenile, juvenile to adult, adult to marketable. Since culture management and genetics were standardized significant differences verified among crop performance could be mostly related to environmental effects. Time series of temperature and chlorophyll a (remote sensing data) from crop periods displayed significant seasonal and interannual variation. As expected...

Climatic patterns and physical controls of chlorophyll-a in the Northeast Atlantic

Valente, André dos Santos Franca Gaspar
Fonte: Universidade dos Açores Publicador: Universidade dos Açores
Tipo: Tese de Doutorado
Publicado em 17/12/2013 ENG
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Tese de Doutoramento, Física, 17 de Dezembro de 2013, Universidade dos Açores.; Chlorophyll-a concentration is one of the most commonly used indicators of phytoplankton biomass, the basis of the marine food chain. Patterns of chlorophyll-a can be driven by many environmental factors, such has meteorological and oceanographic processes that regulate the available light and nutrients for phytoplankton growth. The identification of physical mechanisms responsible for observed chlorophyll-a patterns is key to predict and understand the effect of climate on phytoplankton. Satellite data, with their unprecedented spatial and temporal coverage, provides an unique source of observations to elucidate on these physical-biological interactions. This study describes the distribution and variability of chlorophyll-a in the Northeast Atlantic using satellite images of ocean colour and identifies underlying physical mechanisms using complementary satellite, in-situ and model data. Long-term changes in oceanographic properties were firstly analyzed for a better understanding of chorophyll-a variability. Simultaneous reductions in the southward flow and increases in temperature in the upper ocean (0-500 m) were observed in the eastern basin. These results support the hypothesis that the colder and fresher waters of the early 1990's were replaced by warmer and more saline waters after 2000...

Relationship between photochemical efficiency (JIP-Test Parameters) and portable chlorophyll meter readings in papaya plants

Castro,Fernanda Assumpção; Campostrini,Eliemar; Torres Netto,Alena; Viana,Leandro Hespanhol
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
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The Portable Chlorophyll Meter (PCM) is used to estimate the total chlorophyll and leaf nitrogen content of various species. Since there is a relationship between the chlorophyll concentration and the photochemical efficiency, a relationship can also be established between the PCM readings and some fluorescence variables to provide information on photosystem II (PSII) structure and activity. Papaya (Carica papaya L.) plants ['Sunrise Solo' (leaves with intense green coloring) and 'Golden' cultivars (leaves with yellow-green coloring) were grown in a greenhouse with 30% interception of photosynthetically active photon flux density. The plants were cultivated in 15L plastics pots. Ninety to 100 days after planting the older leaves turned yellow and the chlorophyll fluorescence variables and PCM readings were measured. At low PCM values (less than 30 to 'Sunrise Solo' and less than 20 to 'Golden') the PSII structure and activity were damaged, which is likely related to a reduction in the numbers of active reaction centers (RC/CS0). At higher PCM values the chlorophyll a fluorescence variables (ABS/RC, DI0/RC, TR0/CS0 e ET0/CS0) that are related to PSII structure and activity PSII were not responsive. These results indicated that the effects of chlorophyll content measured by PCM on the photochemical phase of photosynthesis evaluated by chlorophyll fluorescence occur after the degradation of chlorophyll molecules is initiated. In papaya the Portable Chlorophyll Meter (SPAD-502) was shown to be suitable for diagnosis of PSII energy distribution under N stress and senescence.

Chlorophyll disappearance and chlorophyllase activity during ripening of Capsicum annuum L fruits

Hornero-Méndez, Dámaso; Mínguez Mosquera, María Isabel
Fonte: Society of Chemical Industry Publicador: Society of Chemical Industry
Tipo: Artículo Formato: 4085 bytes; image/gif
ENG
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The disappearance of chlorophyll pigments and involvement of chlorophyllase during fruit ripening of seven Capsicum annuum cultivars (Delfin, Mana, Belrubi, NuMex, Agridulce, Bola and Negral) have been studied. Chlorophyll pigments decreased and eventually disappeared from the red cultivars during ripening. In contrast, the green cultivar Negral, a chlorophyll-retaining variety, showed reduced disappearance of chlorophyll pigments, and the fully ripe fruits retained chlorophylls. Chlorophyllase activity followed a consistent pattern of variation in all the red cultivars which was concomitant with the disappearance of chlorophyll. In the ripe stage the six red cultivars preserved their chlorophyllase activity, reflecting a high rate of chloroplast-to-chromoplast transformation. The green cultivar (Negral) showed maximum chlorophyllase activity in the late stages of ripening. Thus increasing activity of chlorophyllase, a constitutive chloroplast enzyme, could be associated with a new genesis of both chloroplast (regreening) and chromoplast constituents. The coexistence of chlorophyll and a high level of chlorophyllase activity in ripe fruits of the Negral cultivar suggests that chlorophyll catabolism may be affected in several ways...

Variation in nutrition along time and relative chlorophyll content of Leucospermum cordifolium cv. ‘High Gold’, and their relationship with chlorotic sypmptoms

Fernández Falcón, Marino; Hernández, M.; Álvarez, Carlos Enrique; Borges, Andrés A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 2373 bytes; 311914 bytes; text/plain; application/pdf
ENG
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7 pages, 4 figures, 5 tables.-- Available online Oct 17, 2005.; Foliar samples, SPAD-502 measurements (both along the growing season), and soil samples were taken from protea plants (Leucospermum cordifolium), cultivar ‘High Gold’ cultivated in six commercial plantations of La Palma Island (Canarian Archipelago). Soil data (pH, available P, Ca, Mg, K and Na, and EC) ranged within normal levels for proteas, though O.M. was high. Drainage decreased the potential problem that could be caused by the high clay content of the soils. Leaves showed high concentrations of N, K, Mg, and Na, while Ca and Cu were normal. On the other hand, Fe and Zn presented some low foliar levels, while Mn values fluctuated depending upon the different plantations. N contents were higher in spring, and those of K, Ca, Mg, and Na increased with time. Relative chlorophyll contents (SPAD-502 measurements) were compared with macro- (N, P, Na, K, Ca, Mg) and micro- (Cu, Fe, Mn, Zn) foliar levels. Results showed no positive correlation between leaf chlorophyll and N content. Higher leaf N concentrations were observed in chlorophyll deficient than chlorophyll sufficient leaves at one site and vice versa at another site. In contrast, lower Mn, Fe and Ca concentrations...

Effects of canopy LAI, crown coverage, and view angle on retrieval of leaf chlorophyll content in forest canopies

Hu, B.; Miller, J. R.; Goel, N. S.; Zarco-Tejada, Pablo J.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 8775 bytes; application/pdf
ENG
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36.96%
Presented at the International Symposium of Spectral Sensing Research (ISSSR), Quebec Cityg (Canada), June 10th-15th, 2001.; In this study, we used simulated data created by SPRINT and PROSPECT to investigate issues on retrieval of leaf Chlorophyll content in sugar maple canopies. Two optical indices, the reflectance index R750/R710 and the derivative index D715/D710, were employed. As anticipated, these two indices have strong correlation with Chlorophyll content with R2 over 0.99 at leaf level. At canopy level, for nadir observations, the correlation between the derivative index and leaf Chlorophyll content is 0.96 for canopies with crown coverage of 90, 75, 50 and 25 percent and canopy LAI of 4, while the correlation between the reflectance index and leaf Chlorophyll content is 0.50. Our results also show that the relationship between the derivative index and leaf Chlorophyll content derived from closed canopies can be used to predict the leaf Chlorophyll content for open canopies even for crown coverage of 25 percent with RMSE of 6.3 mg/cm2. However, with the reflectance index, RMSE increases to over 15 mg/cm2 when the relationship between the reflectance index and leaf Chlorophyll content is used for open canopies with crown coverage of 50 percent or less.; Peer reviewed

Spectroscopic studies of Photosystem II in chlorophyll d -containing Acaryochloris marina

Razeghifard, Mohammad; Chen, Min; Hughes, Joseph; Freeman, Joel; Krausz, Elmars; Wydrzynski, Thomas
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
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Photosystem II (PSII) electron transfer (ET) in the chlorophyll d-containing cyanobacterium Acaryochloris marina (A. marina) was studied by time-resolved electron paramagnetic resonance (EPR) spectroscopy at room temperature, chlorophyll fluorescence, and low-temperature optical spectroscopy. To maximize the ability to measure PSII ET in the intact cells of this organism, growth conditions were optimized to provide the highest specific O2 activity and the instrumental parameters for the EPR measurements of tyrosine Z (YZ) reduction were adjusted to give the best signal-to-noise over spectral resolution. Analysis of the YZ. reduction kinetics revealed that ET to the oxygen-evolving complex on the donor side of PSII in A, marina is indistinguishable from that in higher plants and other cyanobacteria. Likewise, the charge recombination kinetics between the first plastoquinone acceptor QA and the donor side of PSII monitored by the chlorophyll fluorescence decay on the seconds time scale are not significantly different between A. marina and non-chlorophyll d organisms, while low-temperature optical absorption spectroscopy identified the primary electron acceptor in A. marina as pheophytin a. The results indicate that, if the PSII primary electron donor in A. marina is made up of chlorophyll d instead of chlorophyll a...

Optical properties of grapevine leaves: reflectance, transmittance, absorptance and chlorophyll concetration

Cabello-Pasini,Alejandro; Macías-Carranza,Víctor
Fonte: Colegio de Postgraduados Publicador: Colegio de Postgraduados
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
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Leaf absorptance (A), transmittance (T) and reflectance (R) of visible solar radiation strongly correlate with chlorophyll concentration in a number of plant species, however, little is known about the optical properties of grapevine leaves. Consequently, the objective of this study was to evaluate the optical properties of intact leaves for estimating chlorophyll concentration in Cabernet Sauvignon, Merlot and Tempranillo vaieties. Leaves from Cabernet Sauvignon, Merlot and Tempranillo vines were collected at San Antonio de las Minas, Baja California, México, in 2009, and A, T and R determined with a spectroradiometer. While leaf age played a significant role on the leaf chlorophyll concentration, the chlorophyll a+b concentration vs. R, T and A (evaluated from 400 to 700 nm) in the leaves of the three varieties studied followed an exponential relationship. There was a clear difference in the chlorophyll content, and the R, T, and A spectra among leaves of different ages in all three varieties studied. Reflectance values at wavelengths (λ) >750 nm increased as the age of the leave increased while λ values at approximately 550 nm remained relatively constant. The mean A values of the Merlot (0.80±0.07), Cabernet (0.82±0.05) and Tempranillo leaves (0.78±0.08) studied were below the assumed A value of 0.84 for vascular plants. Our observations suggest that while the 0.84 A value is acceptable for estimating absolute electron transport rates (ETR) in mature grapevine leaves...

Leaf chlorophyll content estimation in the Monarch Butterfly Biosphere Reserve

España Boquera,Ma. Luisa; Lobit,Philippe; Castellanos Morales,Vilma
Fonte: Sociedad Mexicana de Fitogenética A.C. Publicador: Sociedad Mexicana de Fitogenética A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2010 EN
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Chlorophyll is an essential element of photosynthesis and its content in plant leaves indicates their photosynthetic capacity as well as the presence of stress or diseases. The purpose of this work was to evaluate the feasibility of estimating chlorophyll content in the Monarch Butterfly Biosphere Reserve forest (Sierra Chincua sanctuary, México) based on vegetation indices calculated by using hyperspectral reflectance measurements of plant leaves. This study focused on oyamel (Abies religiosa L.) which is the main tree specie of this area. Leaf samples were taken on 140 trees and analyzed for chlorophyll a and b, nitrogen and carbon content. The hyperspectral reflectance spectra were measured on each sample and different vegetation indices were calculated. Results showed that the indices best correlated with chlorophyll content were the red edge position index (r = 0.531) and the red edge position chlorophyll reflectance index (r = 0.506), followed by the MERIS terrestrial chlorophyll index (r = 0.497) and the green chlorophyll reflectance index (r = 0.472). Although there was a significant correlation between nitrogen and chlorophyll content, none of the indices studied here correlated with nitrogen content. The influence of various environmental factors (altitude...