The mangrove habitat exhibits many unique physical features, one of the most important of which is a salinity gradient. Photosynthetic rates, as measured by leaf stomatal conductance and leaf chlorophyll fluorescence induction, were tested as indicators of salinity stress in seedlings of the red mangrove, Rhizophora mangle, grown under five different salinity levels: 0, 15, 30, 45, and 60 parts...

The effects of copper toxicity on the photosynthetic activities of Avicennia germinans was investigated using two CuSO4 concentrations (0.062 and 0.33 M) added in Hoagland's solution in an aerated hydroponic system. Photosynthesis and chlorophyll fluorescence were measured after 30 h of copper stress. Results obtained in this study show that increasing levels of Cu(+2) of 0.062 and 0.33 M Cu(+2...

Sun-induced canopy chlorophyll fluorescence in both the red (FR) and far-red (FFR) regions was estimated across a range of temporal scales and a range of species from different plant functional types using high resolution radiance spectra collected on the ground. Field measurements were collected with a state-of-the-art spectrometer setup and standardized methodology. Results showed that differ...

It has long been known that quinones quench chlorophyll fluorescence. This study reports the parameters of the fluorescence quenching of chlorophyll a by 1,4-benzoquinone, in ethanol, using the nonlinear analysis. The fluorescence intensity was measured at 670 nm for the blue and red excitation wavelengths: 430 nm and 650 nm, respectively. The quinone concentration in the samples ranged from 3....

The aggregation dependent correlation between fluorescence quenching and the electronic carotenoid– chlorophyll interactions, / S1 Chl Coupling , as measured by comparing chlorophyll fluorescence observed after twoand one-photon excitation, has been investigated using native LHC II samples as well as mutants lacking Chl 2 and Chl 13. For native LHC II the same linear correlation between / S1 Ch...

The first seagoing test of a prototype laser/fiber-optic system for in situ detection of ocean chlorophyll fluorescence is described. Radiation at 488 nm originating from a shipboard argon laser was transmitted through 20 of 200-microm core optical fiber to the distal tip mounted on the microstructure profiler, the Rapid Sampling Vertical Profiler. The backscattered fluorescence emission signal...

The pesticide PCP was shown to inhibit the Hill reaction in broken chloroplasts (I50 = 15 jam) and to quench chlorophyll fluorescence. Both effects require preillumination. In contrast to the common “phenol-type” inhibitors, neither inhibition of Hill reaction nor chlorophyll fluorescence quench were affected by pretreatment of chloroplast with trypsin instead o f preillumination. An inhibition...

Reflectance spectra from 400 to 750 nm were measured in Lake Kinneret, when low phytoplankton stock prevailed, with chlorophyll concentrations from 3.1 to 7.3 pg/l. Algorithms for estimation of chlorophyll (CHL) concentration were devised using reflectances in the blue and green region of the spectrum and natural solar induced fluorescence. The fluorescence was calculated either from the reflec...

Fluorescence spectroscopy is applied to study the influence of plasmon excitations in spherical Au nanoparticles on the optical properties of chlorophyll-containing light-harvesting complexes. The separation between the two nanostructures is controlled via silica layer with varied thickness. We observe strong increase of the emission intensity for a 12nm-thick spacer and the increase is accompa...