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 (...

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...

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...

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 ...

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...

Several photochemical and spectral properties of maize (Zea mays) bundle sheath and mesophyll chloroplasts are reported that provide a better understanding of the photosynthetic apparatus of C(4) plants. The difference absorption spectrum at 298 K and the fluorescence excitation and emission spectra of chlorophyll at 298 K and 77 K provide new information on the different forms of chlorophyll a...

Huanglongbing (HLB) is one of the most destructive diseases of citrus, which has posed a serious threat to the global citrus production. This research was aimed to explore the use of chlorophyll fluorescence imaging combined with feature selection to characterize and detect the HLB disease. Chlorophyll fluorescence images of citrus leaf samples were measured by an in-house chlorophyll fluoresce...

It has been suggested that some biological processes are equivalent to computation, but quantitative evidence for that view is weak. Plants must solve the problem of adjusting stomatal apertures to allow sufficient CO(2) uptake for photosynthesis while preventing excessive water loss. Under some conditions, stomatal apertures become synchronized into patches that exhibit richly complicated dyna...

Chlorophyll a fluorescence is a highly sensitive, non-destructive, and reliable tool for measuring, rather quickly, photosynthetic efficiency, particularly of Photosystem II (PSII), the water-plastoquinone oxidoreductase. We briefly review here the connection between the fast (up to 2 s) chlorophyll fluorescence rise and PSII, as well as the empirical use of the fluorescence rise kinetics in un...