Search results for " Chlorophyll a"
showing 8 items of 8 documents
In vivo photoprotection mechanisms observed from leaf spectral absorbance changes showing VIS–NIR slow-induced conformational pigment bed changes
2019
Abstract Regulated heat dissipation under excessive light comprises a complexity of mechanisms, whereby the supramolecular light-harvesting pigment–protein complex (LHC) shifts state from light harvesting towards heat dissipation, quenching the excess of photo-induced excitation energy in a non-photochemical way. Based on whole-leaf spectroscopy measuring upward and downward spectral radiance fluxes, we studied spectrally contiguous (hyperspectral) transient time series of absorbance A(λ,t) and passively induced chlorophyll fluorescence F(λ,t) dynamics of intact leaves in the visible and near-infrared wavelengths (VIS–NIR, 400–800 nm) after sudden strong natural-like illumination exposure. …
The application protocol impacts the effectiveness of biocides against lichens
2020
Abstract This work analyzed the influence of different application protocols on the efficacy of two biocides against the foliose lichen Xanthoparmelia tinctina on the sandstones of the Roman Archaeological site of Luni (Italy). The hypotheses that (a) biocide application tools (brush vs. poultice), (b) pre-treatment hydration, and (c) post-treatment washing may affect devitalization success were verified by monitoring chlorophyll a fluorescence of thalli, both in situ and in laboratory conditions. The hypothesis that (d) stone substrate may act as reservoir for later biocide release under repeated cycles of wetting and drying was also assayed. Analyses confirmed the importance of the applic…
Species- and site-specific efficacy of commercial biocides and application solvents against lichens
2017
Abstract Control of lichens on stone cultural heritage is mostly achieved by a combination of mechanical removal with biocide applications. However, there is a lack of scientific evidence on the efficacy of different biocides on different species, and on the consistency of biocide effects on heritage sites in different environmental conditions. This results in some uncertainty when conservation interventions to control lichens are routinely defined on the basis of restoration tradition or empirical evaluation, without experimental measures of how lichens respond. In this work, we quantitatively evaluated (a) the efficacy of five commercially-available biocides, applied using a brush or with…
Physiological Aspects of Nitrogen Fertilizer Impact on Latvian Origin Cannabis Sativa L .
2015
The aim of the present study was to evaluate nitrogen fertilizer impact on photosynthesis and yield of hemp, applying modern non-destructive methods. The main object of the investigation – hemp cultivar of Latvian origin ‘Pūriņi’. Laboratory and field experiments showed diverse effects of different nitrogen fertilizer doses on various parameters. Additional nitrogen fertilizer dose of 60 kg ha-1 is most effective as evaluated by chlorophyll content in hemp leaves and changes of chlorophyll a fluorescence parameters. Nitrogen fertilizer negatively affected fiber content in hemp stems, therefore while cultivating hemp only for fiber production use of nitrogen fertilizer should be reduced. Acc…
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…
Structural stability and properties of three isoforms of the major light-harvesting chlorophyll a/b complexes of photosystem II.
2008
AbstractThree isoforms of the major light-harvesting chlorophyll (Chl) a/b complexs of photosystem II (LHCIIb) in the pea, namely, Lhcb1, Lhcb2, and Lhcb3, were obtained by overexpression of apoprotein in Escherichia coli and by successfully refolding these isoforms with thylakoid pigments in vitro. The sequences of the protein, pigment stoichiometries, spectroscopic characteristics, thermo- and photostabilities of different isoforms were analysed. Comparison of their spectroscopic properties and structural stabilities revealed that Lhcb3 differed strongly from Lhcb1 and Lhcb2 in both respects. It showed the lowest Qy transition energy, with its reddest absorption about 2 nm red-shifted, an…
Growth and reproductive simulation of candidate shellfish species at fish cages in the Southern Mediterranean: Dynamic Energy Budget (DEB) modelling …
2012
Abstract A Dynamic Energy Budget (DEB) model is used to simulate growth and reproduction of the shellfish Mytilus galloprovincialis and Crassostrea gigas in an integrated multi-trophic aquaculture (IMTA) farm scenario situated in the Southern Mediterranean (the Gulf of Castellammare, Sicily). We modelled the effect of primary production enrichment at fish cages on shellfish growth and life history traits using 4 years-hourly temperature data (01 January 2006–31 December 2009) at a depth of 1 m. Outputs of the DEB simulations were: the maximum theoretical total shell length of shellfish, the potential reproductive outputs and the mean annual von Bertalanffy growth rate. There was a mean incr…
Assessment of Sentinel-2-MSI Atmospheric Correction Processors and In Situ Spectrometry Waters Quality Algorithms
2022
The validation of algorithms developed from in situ reflectance to estimate water quality variables has the challenge of atmospheric correction (AC) when applied to satellite images. Estimating water quality variables from satellite images requires an accurate estimation of remote sensing reflectances (Rrs) which vary according to the AC applied. Validation processes for both Rrs and water quality algorithms were carried out, relating the in situ Rrs (convoluted to Sentinel-2-MSI spectral response function) with the satellite Rrs coming from different ACs (C2RCC, C2X, C2XC, and Polymer), and also relating the in situ water quality variable data with estimated water quality variable values, …