A novel emerging technology for the assessment of the photoprotective 'power' of non-photochemical fluorescence quenching (NPQ) has been reviewed and its insightful outcomes are explained using several examples. The principles of the method are described in detail as well as the work undertaken for its justification. This pulse amplitude modulated chlorophyll fluorescence approach has been appl...

Toxicity and deficiency of essential trace elements like Cu are major global problems. Here, environmentally relevant sub-micromolar concentrations of Cu (supplied as CuSO4) and simulations of natural light- and temperature cycles were applied to the aquatic macrophyte Ceratophyllum demersum. Growth was optimal at 10nM Cu, while PSII activity (Fv/Fm) was maximal around 2 nM Cu. Damage to the PS...

Although sunlight provides the energy necessary for plants to survive and grow, light can also damage reaction centers of photosystem II (PSII) and reduce photochemical efficiency. To prevent damage, plants possess photoprotective mechanisms that dissipate excess excitation. A subset of these mechanisms is collectively referred to as NPQ, or nonphotochemical quenching of chlorophyll a fluoresce...

Water deficiency is one of the most important environmental stresses that limit plant growth and crop production. Measurement of chlorophyll fluorescence parameters is considered as an important indicator to evaluate the photosynthetic apparatus. In the present study, the effects of regulated water deficit, investigated in four water-regimes in pistachio orchard with 12-year-old trees of Akbari...

Photosynthetic organisms avoid photodamage to photosystem II (PSII) in variable light conditions via a suite of photoprotective mechanisms called nonphotochemical quenching (NPQ), in which excess absorbed light is dissipated harmlessly. To quantify the contributions of different quenching mechanisms to NPQ, we have devised a technique to measure the changes in chlorophyll fluorescence lifetime ...

BACKGROUND AND AIMS Cost-benefit models predict that carnivory can increase the rate of photosynthesis (A(N)) by leaves of carnivorous plants as a result of increased nitrogen absorption from prey. However, the cost of carnivory includes decreased A(N) and increased respiration rates (R(D)) of trapping organs. The principal aim of the present study was to assess the costs and benefits of carniv...

Second year needles of Lodgepole pine (Pinus contorta L.) were exposed for 6 weeks to either simulated control summer ['summer'; 25 °C/250 photon flux denisty (PFD)], autumn ('autumn'; 15°C/250 PFD) or winter conditions ('winter'; 5 °C/250 PFD). We report that the proportion of linear electron transport utilized in carbon assimilation (ETR(CO2)) was 40% lower in both 'autumn' and 'winter' pine ...

To investigate how high light affects the responses of photosynthesis to heat stress, the effects of high temperature (25-42.5 degrees C) either in the dark or in the light (1000 micromol m(-2) s(-1)) on photosystem II (PSII) photochemistry and the xanthophyll cycle were investigated in rice plants. At temperatures higher than 35 degrees C, there was a decrease in the CO(2) assimilation rate, a...

The chlorophyll fluorescence imaging technique is a valuable tool to study the impact of heavy metal stress in plants. The aim of this paper was to investigate the influence of Cd on photosynthetic apparatus of white cabbage (Brassica oleracea subsp. capitata f. alba) plants. Two cabbage cultivars ‘Ditmarska Najwcześniejsza’ (‘DN’; early) and ‘Amager Polana’ (‘AP’; late) were used. Cd was appli...

Sea-ice algae play a crucial role in the ecology and biogeochemistry of sea-ice zones. They not only comprise base ecosystems, but also seed populations extensive ice-edge blooms during ice melt. Ice must rapidly acclimate to dynamic light environments, from low under sea high within open waters. Recently, iron (Fe) deficiency has been reported for diatoms eastern Antarctic pack ice. Low Fe ava...