An apparatus is described which permits the simultaneous measurement of O(2) evolution and chlorophyll a fluorescence from illuminated discs or pieces of green leaves. O(2) is measured in the gas phase in a temperature-controlled chamber of approximately 5-milliliter capacity. Calibration is effected by injection of air through vents. Response time is approximately 1.5 seconds for O(2), and ful...

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 (...

to explore the function of light-harvesting complex protein (lhcp) in arabidopsis growth and development, the leclere and bartel seed collection was screened. in this collection randomly cloned cdnas are expressed under the camv35s promoter. a pale green line has been identified and characterized in more details. analysis of the inserted cdna in the pale green line showed it encodes lhcb1 prote...

Chlorophyll-a fluorescence induction is a rapid technique for measuring photosynthetic electron transport in plants. To assess chlorophyll-a fluorescence as a bioindicator of effects of polycyclic aromatic hydrocarbon mixtures, chlorophyll-a fluorescence parameters and plant growth responses to exposure to the wood preservative creosote were examined in the aquatic plants Lemna gibba and Myriop...

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...