Search results for "photos"
showing 10 items of 701 documents
The antagonistic effect of UV radiation on warming or nitrate enrichment depends on ecotypes of freshwater macroalgae (Charophytes).
2019
Increases in ultraviolet radiation (UVR), a negative global change factor, affect aquatic primary producers. This effect is expected to be modulated by other global change factors, and to be different for populations adapted to different environments. A common garden experimental approach using freshwater green macroalgae, the cosmopolitan charophyte species Chara hispida and C. vulgaris, allowed us to test whether the beneficial increases in water temperature (T) and nitrate concentration (N) mitigate negative UVR effects. Also, whether these interactions would be not only species-specific but also according to the origin of the population; therefore, two populations of each species were u…
Carbon isotope composition of plant photosynthetic tissues reflects a Crassulacean Acid Metabolism (CAM) continuum in the majority of CAM lineages
2021
Abstract The stable carbon isotope composition of plant tissues, commonly expressed as δ13C, holds a wealth of information about photosynthetic pathway, water relations and stress physiology. Crassulacean acid metabolism (CAM) is a derived form of photosynthesis that allows plants to fix carbon at a higher water-use efficiency compared to the ancestral C3 photosynthesis. While the central carbon-fixing enzyme of C3 plants, Rubisco, strongly discriminates against the heavy 13C isotope, CAM is characterized by a dual use of Rubisco and the much less discriminating PEP carboxylase as carbon-fixing enzymes, causing the δ13C values of CAM plant tissues to be generally less negative than those fo…
Relation of lenacil metabolism with growth inhibition of acer pseudoplatanus cell suspension
1983
Abstract The action of lenacil, a herbicide which inhibits photosynthesis, was studied on Acer pseudoplatanus cell suspensions. The compound was quickly and thoroughly metabolized by cells into two major chloroform-extractable metabolites, but cell growth was temporarily inhibited while some cells were killed. As cell suspensions were non-photosynthetic, the data suggest that lenacil has site(s) of action other than that of photosynthesis. However, as the effects on photosynthesis occur at much lower concentrations (Hilton et al., Weeds, 12 (1964) 129), the effects on cell growth may be considered as secondary.
Use of chlorophyll fluorescence induction kinetics to study translocation and detoxication of DCMU-type herbicides in plant leaves
1984
Transient levels of the fluorescence induction rise were used to quantify partial photosynthesis inhibition by DCMU -type herbicides in whole leaves. Assays in different crop or weed species showed a good accuracy in measurements (generally, variation was lower than 5%). This technique was applied to the problem of varietal selectivity of wheat towards chlortoluron.
Solute transporters in plant thylakoid membranes
2010
International audience; Plants utilize sunlight to drive photosynthetic energy conversion in the chloroplast thylakoid membrane. Here are located four major photosynthetic complexes, about which we have great knowledge in terms of structure and function. However, much less we know about auxiliary proteins, such as transporters, ensuring an optimum function and turnover of these complexes. The most prominent thylakoid transporter is the proton-translocating ATP-synthase. Recently, four additional transporters have been identified in the thylakoid membrane of Arabidopsis thaliana, namely one copper-transporting P-ATPase, one chloride channel, one phosphate transporter, and one ATP/ADP carrier…
Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks
2020
Abstract The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co‐acting…
Physiological Performance of a Coastal Marsh Plant Hydrocotyle vulgaris in Natural Conditions in Relation to Mineral Nutrition and Mycorrhizal Symbio…
2020
Abstract Fluctuating soil salinity and competition for light are the main factors affecting plant distribution and performance in coastal salt marshes. The aim of the present study was to assess plant performance by means of non-destructive instrumental methods in a highly heterogeneous natural habitat. More specifically, environmental factors affecting growth and physiological performance of a clonal plant Hydrocotyle vulgaris L. were investigated. Changes in soil salinity, soil mineral characteristics, leaf nutrient concentrations, morphological parameters, chlorophyll fluorescence, and mycorrhizal symbiosis were analysed in different experimental plots of naturally growing H. vulgaris pl…
Chlorophyll a fluorescence illuminates a path connecting plant molecular biology to Earth-system science
2021
Remote sensing methods enable detection of solar-induced chlorophyll a fluorescence. However, to unleash the full potential of this signal, intensive cross-disciplinary work is required to harmonize biophysical and ecophysiological studies. For decades, the dynamic nature of chlorophyll a fluorescence (ChlaF) has provided insight into the biophysics and ecophysiology of the light reactions of photosynthesis from the subcellular to leaf scales. Recent advances in remote sensing methods enable detection of ChlaF induced by sunlight across a range of larger scales, from using instruments mounted on towers above plant canopies to Earth-orbiting satellites. This signal is referred to as solar-in…
Lake zooplankton delta13C values are strongly correlated with the delta13C values of distinct phytoplankton taxa
2016
Article
Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Ita…
2017
Abstract We investigated changes in the chemical characteristics of evaporating seawater under the influence of microbial activity by conducting geochemical analyses of the brines and evaporite sediments collected from solar salterns in Trapani, Italy. The microbial activity had a substantial effect on the carbonate system parameters. Dissolved inorganic carbon (DIC) was substantially removed from the brine during the course of evaporation from the seawater to the point where calcium carbonate precipitates, with an accompanying decrease in its carbon isotopic composition (δ 13 C DIC ) to as low as −10.6‰. Although the removal of DIC was due to calcium carbonate precipitation, photosynthesis…