Smirnovia iranica, a native valuable woody species from Fabaceae, is an adaptable plant of central sandy areas of Iran. Changes in chlorophyll fluorescence and photosynthetic pigments characteristics were analyzed in the course of phenological stages including vegetative, flowering, seed ripening, and seed falling stages, respectively (VS, FS, SRS, and SFS). The results obtained from analysis o...

Energy taken up by light absorption of the leaf pigments is transformed in the process of the photosynthetic quantum conversion into photosynthesis, chlorophyll fluorescence and thermal dissipation. The mostly inverse correlation between chlorophyll fluorescence and photosynthetic activity has been extensively studied in the past, whereas only few studies dealt with the thermal dissipation. In ...

Population fluctuations are often driven by an interplay between intrinsic population processes and extrinsic environmental forcing. To investigate this interplay, we analyzed fluctuations in coastal phytoplankton concentration in relation to the tidal cycle. Time series of chlorophyll fluorescence, suspended particulate matter (SPM), salinity and temperature were obtained from an automated mea...

Exposure of plants to irradiances far above the light saturation point of photosynthesis, known as highlight stress, induces various responses including light adaptation of the photosynthetic apparatus and chloroplast ultrastructure by formation of sun-type chloroplasts. The latter possess a lower cross section for light absorption (less light-harvesting chlorophyll proteins) and higher rates o...

A method is described to determine germination by blue-light excited red fluorescence in the positively photoblastic spores of Dryopteris paleacea Sw. This fluorescence is due to chlorophyll as evidenced from 1) a fluorescence-emission spectrum in vivo, where a bright fluorescence around 675 nm is obtained only in red light (R)-irradiated spores and 2) in vitro measurements with acetone extrac...

A mnode-locked laser was used to measure fluorescence decay down to 80 picoseconds. Measurements on the fluorescence of methylene blue quenchled with potassium iodide demonstrate the effectiveness of the method. Fluorescence decay times of chlorophyll b (3.87 +/- 0.05 nianoseconds) and c-phycocyanin (1.14 +/- 0.01 nanoseconds) in vitro and chlorophyll a in the green alga Chlorella pyrenoidosa (...

The interactions of the xanthophylls zeaxanthin, antheraxanthin and violaxanthin with chlorophyll, which are relevant for the chlorophyll fluorescence quenching in the non-photochemical quenching (NPQ) process in green plants, are investigated by means of quantum chemical methods. In particular, we use a hybrid approach consisting of time-dependent density-functional theory (TDDFT) and configur...

Several molecules absorb light energy which they emit after a time difference (lifetime) as radiation energy. Molecules remain at a low energy level or the ground electronic singlet state (So) or the lowest vibrational level at room temperature (Noomnarm and Clegg, 2009). On absorption of a photon, the molecule is excited from So to the first electronic excited singlet state S1 within < 10-15 s...