Search results for "Photosynthesi"

When do different C4 leaf anatomies indicate independent C4 origins? Parallel evolution of C4 leaf types in Camphorosmeae (Chenopodiaceae).

2014

Broad-scale phylogenetic studies give first insights in numbers, relationships, and ages of C 4 lineages. They are, however, generally limited to a model that treats the evolution of the complex C4 syndrome in different lineages as a directly comparable process. Here, we use a resolved and well-sampled phylogenetic tree of Camphorosmeae, based on three chloroplast and one nuclear marker and on leaf anatomical traits to infer a more detailed picture of C4 leaftype evolution in this lineage. Our ancestral character state reconstructions allowed two scenarios: (i) Sedobassia is a derived C3/C4 intermediate, implying two independent gains of C4 in Bassia and Camphorosma; or (ii) Sedobassia is a…

The role of size and protein shells in the toxicity to algal photosynthesis induced by ionic silver delivered from silver nanoparticles

2019

Abstract Because of their biocide properties, silver nanoparticles (AgNPs) are present in numerous consumer products. The biocidal properties of AgNPs are due to both the interactions between AgNP and cell membranes and the release of dissolved silver (Ag+). Recent studies emphasized the role of different nanoparticle coatings in complexing and storing Ag+. In this study, the availability of dissolved silver in the presence of algae was assessed for three AgNPs with different silver contents (59%, 34% and 7% of total Ag), silver core sizes and casein shell thicknesses. The impact of ionic silver on the photosynthetic yield of Chlamydomonas reinhardtii was used as a proxy to estimate the amo…

Sexes in gynodioeciousGeranium sylvaticumdo not differ in their isotopic signature or photosynthetic capacity

2017

• In gynodioecious plants, females are expected to produce more or better seeds than hermaphrodites in order to be maintained within the same population. Even though rarely measured, higher seed production can be achieved through differences in physiology. • In this work, we measured sexual dimorphism in several physiological traits in the gynodioecious plant Geranium sylvaticum. Photosynthetic rate, stomatal conductivity, transpiration rate, water use efficiency and isotopic signatures were measured in plants growing in two habitats differing in light availability. • Females have been reported to produce more seeds than hermaphrodites. However, we did not observe any significant difference…

A global database of C 4 photosynthesis in grasses

2014

Influence of cadmium and nickel on growth, net photosynthesis and carbohydrate distribution in rice plants

1992

Six day old rice seedlings (Oryza sativa L. cv. Bahía) were grown for 5 or 10 days in a nutrient solution with either Cd (0.01, 0.1 mmol/l) or Ni (0.1, 0.5 mmol/l). Both Cd and Ni reduced the length of shoots and roots depending on the concentration and type of ion tested. On the other hand, the dry weight to fresh weight ratio was increased by heavy metal treatments, especially in the aerial part of 0.5 mmol/l Ni treated plants. The application of 0.1 mmol/l Cd and 0.5 mmol/l Ni to the seedlings produced an inhibition of the transport of carbohydrate reserves from the seeds from which plants were developing, to the rest of the plant. Net photosynthesis was also inhibited in treated plants.…

Quantitative global mapping of terrestrial vegetation photosynthesis

2017

Although traditional remote sensing systems based on spectral reflectance can already provide estimates of the 'potential' photosynthetic activity of terrestrial vegetation through the quantification of total canopy chlorophyll content or absorbed photosynthetic radiation, the determination of the 'actual' photosynthetic activity of terrestrial vegetation requires information about how the absorbed light is used by plants, such as vegetation fluorescence, using very high spectral resolution spectroscopy in the range 650-800 nm. The Fluorescence Explorer (FLEX) mission, selected in November 2015 as the 8th Earth Explorer by the European Space Agency (ESA), carries the FLORIS spectrometer, wi…

Evaluating the predictive power of sun-induced chlorophyll fluorescence to estimate net photosynthesis of vegetation canopies: A SCOPE modeling study

2016

Abstract Progress in imaging spectroscopy technology and data processing can enable derivation of the complete sun-induced chlorophyll fluorescence (SIF) emission spectrum. This opens up opportunities to fully exploit the use of the SIF spectrum as an indicator of photosynthetic activity. Simulations performed with the coupled fluorescence–photosynthesis model SCOPE were used to determine how strongly canopy-leaving SIF can be related to net photosynthesis of the canopy (NPC) for various canopy configurations. Regression analysis between SIF retrievals and NPC values produced the following general findings: (1) individual SIF bands that were most sensitive to NPC were located around the fir…

Validating an apple dry matter production model with whole canopy gas exchange measurements in the field

1999

The simplified apple dry matter production model developed by Lakso and Johnson (1990) was modified by inputing tree-specific parameters from a study of seasonal growth and gas exchange of 4-year-old Empire/M.9 apple trees, and light and temperature response curves developed for Empire apple organs. Measurements of the seasonal trend of diurnal net C02 and canopy water vapor exchange were made at intervals on three four-year-old 'Empire'/M.9 slender spindle apple trees in the orchard from 10 days after bloom until 25 days after harvest. The tree canopies were enclosed in clear plastic "balloon- type" chambers (similar to Corelli and Magnanini, 1993) that was monitored continuously for more …

2021

Abstract Remote sensing-based measurements of solar-induced chlorophyll fluorescence (SIF) are useful for assessing plant functioning at different spatial and temporal scales. SIF is the most direct measure of photosynthesis and is therefore considered important to advance capacity for the monitoring of gross primary production (GPP) while it has also been suggested that its yield facilitates the early detection of vegetation stress. However, due to the influence of different confounding effects, the apparent SIF signal measured at canopy level differs from the fluorescence emitted at leaf level, which makes its physiological interpretation challenging. One of these effects is the scatterin…

CO2 uptake of Opuntia ficus-indica (L.) Mill. whole trees and single cladodes, in relation to plant water status and cladode age

2013

Most of net photosynthesis determinations in Opuntia ficus-indica come from measurements on individual cladodes. However, they have limitations when used to scale up to whole canopy gas exchange, because a large variability of carbon assimilation may occur within the canopy, due to, among others, differences in cladode age and intercepted radiation or individual cladode response to abiotic stresses. The aim of this work was to evaluate the application of open gas exchange chambers, simultaneously applied around the whole canopy, to measure net CO 2 uptake, continuously over a 24 h period, in single Opuntia ficus-indica (L.) Mill. potted trees and in relation with their water status. Net CO2…