Search results for "Chlorophyll"
showing 10 items of 453 documents
Chlorophyll Concentration Retrieval by Training Convolutional Neural Network for Stochastic Model of Leaf Optical Properties (SLOP) Inversion
2020
Miniaturized hyperspectral imaging techniques have developed rapidly in recent years and have become widely available for different applications. Combining calibrated hyperspectral imagery with inverse physically based reflectance models is an interesting approach for estimating chlorophyll concentrations that are good indicators of vegetation health. The objective of this study was to develop a novel approach for retrieving chlorophyll a and b values from remotely sensed data by inverting the stochastic model of leaf optical properties using a one-dimensional convolutional neural network. The inversion results and retrieved values are validated in two ways: A classical machine learning val…
Influence of Heavy Metal Concentration on Chlorophyll Content in Pleurozium schreberi Mosses
2020
Abstract The aim of biomonitoring is assessment of environment condition. Biomonitoring studies with the use of mosses focus mainly on analytes accumulation and determining elements’ concentrations in the study area. It is often forgotten that a bioindicator should be alive during biomonitoring studies (which can be determined by, e.g., analysis of chlorophyll content). The objective of the carried out research was an assessment of the influence of selected heavy metals concentration: Ni, Cu, Zn, Cd and Pb accumulated by Pleurozium schreberi mosses during 3-month exposition within active biomonitoring, on their vitality, assessed by an analysis of a and b chlorophyll concentrations. The stu…
Multitemporal Monitoring of Plant Area Index in the Valencia Rice District with PocketLAI
2016
Leaf area index (LAI) is a key biophysical parameter used to determine foliage cover and crop growth in environmental studies in order to assess crop yield. Frequently, plant canopy analyzers (LAI-2000) and digital cameras for hemispherical photography (DHP) are used for indirect effective plant area index (PAI(eff)) estimates. Nevertheless, these instruments are expensive and have the disadvantages of low portability and maintenance. Recently, a smartphone app called PocketLAI was presented and tested for acquiring PAI(eff) measurements. It was used during an entire rice season for indirect PAI(eff) estimations and for deriving reference high-resolution PAI(eff) maps. Ground PAI(eff) value…
Interspecific hybridization improves the performance of Lotus spp. under saline stress
2019
Abstract Salinity is one of the most frequent limiting conditions in pasture production for grazing livestock. Legumes, such as Lotus spp. with high forage quality and capable of adapting to different environments, improves pasture performance in restrictive areas. In order to determine potential cultivars with better forage traits, the current study assess the response to salt stress of L. tenuis, L. corniculatus and a novel L. tenuis x L. corniculatus accession. For this purpose, chlorophyll fluorescence, biomass production, ion accumulation and anthocyanins and proanthocyanidins levels have been evaluated in control and salt-treated plants PSII activity was affected by salt in L. tenuis,…
Plant chlorophyll fluorescence: active and passive measurements at canopy and leaf scales with different nitrogen treatments
2015
Highlight We studied for the first time the temporal and spatial limits within which active and passive chlorophyll fluorescence measurements are comparable.
How diffusivity, thermocline and incident light intensity modulate the dynamics of Deep Chlorophyll Maximum in Tyrrhenian Sea
2015
During the last few years theoretical works have shed new light and proposed new hypotheses on the mechanisms which regulate the spatio-temporal behaviour of phytoplankton communities in marine pelagic ecosystems. Despite this, relevant physical and biological issues, such as effects of the time- dependent mixing in the upper layer, competition between groups, and dynamics of non-stationary deep chlorophyll maxima, are still open questions. In this work, we analyze the spatio-temporal behaviour of five phytoplankton populations in a real marine ecosystem by using a one-dimensional reaction-diffusion-taxis model. The study is performed, taking into account the seasonal variations of environm…
Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia)
2016
International audience; This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages.In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be consider…
Status of vulnerable Cystoseira populations along the Italian infralittoral fringe, and relationships with environmental and anthropogenic variables
2018
We analyzed the occurrence and status of infralittoral fringe populations of Cystoseira spp. (Fucales) at thirteen rocky sites around the Italian coastline, and explored the relationships with relevant environmental and anthropogenic variables. We found Cystoseira populations at 11 sites: most were scattered and comprised monospecific stands of C. compressa, and only 6 sites also supported sparse specimens of either C. amentacea var. stricta or C. brachycarpa. Coastal human population density, Chlorophyll a seawater concentrations, sea surface temperature, annual range of sea surface temperature and wave fetch explained most of the variation of the status of C. compressa. We hypothesize a g…
Spatio-temporal dynamics of a planktonic system and chlorophyll distribution in a 2D spatial domain: matching model and data
2017
AbstractField data on chlorophyll distribution are investigated in a two-dimensional spatial domain of the Mediterranean Sea by using for phytoplankton abundances an advection-diffusion-reaction model, which includes real values for physical and biological variables. The study exploits indeed hydrological and nutrients data acquired in situ, and includes intraspecific competition for limiting factors, i.e. light intensity and phosphate concentration. As a result, the model allows to analyze how both the velocity field of marine currents and the two components of turbulent diffusivity affect the spatial distributions of phytoplankton abundances in the Modified Atlantic Water, the upper layer…
Rigid versus Flexible Protein Matrix: Light-Harvesting Complex II Exhibits a Temperature-Dependent Phonon Spectral Density
2018
Dynamics-function correlations are usually inferred when molecular mobility and protein function are simultaneously impaired at characteristic temperatures or hydration levels. In this sense, excitation energy transfer in the photosynthetic light-harvesting complex II (LHC II) is an untypical example because it remains fully functional even at cryogenic temperatures relying mainly on interactions of electronic states with protein vibrations. Here, we study the vibrational and conformational protein dynamics of monomeric and trimeric LHC II from spinach using inelastic neutron scattering (INS) in the temperature range of 20-305 K. INS spectra of trimeric LHC II reveal a distinct vibrational …