Light availability is considered a key factor regulating the thermal sensitivity of reef building corals, where excessive excitation of photosystem II (PSII) further exacerbates pressure on photochemical pathways already compromised by heat stress. Coral symbionts acclimate to changes in light availability (photoacclimation) by continually fine-tuning the photochemical operating efficiency of P...

Melatonin was found in the fresh water characeae Chara australis. The concentrations (~4 μg/g of tissue) were similar in photosynthesizing cells, independent of their position on the plant and rhizoids (roots) without chloroplasts. Exogenous melatonin, added at 10 μM to the artificial pond water, increased quantum yield of photochemistry of photosystem II by 34%. The increased efficiency appear...

Ultraviolet B (UV-B) (280–315 nm) and ultraviolet A (UV-A) (315–400 radiation comprise small portions of the solar but regulate many aspects plant development, physiology metabolism. Until now, how plants respond to UV-B in presence different light qualities is poorly understood. This study aimed assess effects a low dose (0.912 ± 0.074 kJ m –2 day –1 , at 6 h daily UV exposure) combination wit...

Fluorescence imaging represents a non-invasive tool for revealing and understanding spatial heterogeneity in leaf performance caused by external factors, such as abiotic stress. Sun (Rosa meillandina and Chrysanthemum morifolium) and shade (Spathiphyllum wallisii) plants were used to study their tolerance to heat and high illumination. Fluorescence yield, effective PSII quantum yield and non-ph...

Light harvesting as the first step in photosynthesis is of prime importance for life on earth. For a theoretical description photochemical processes during light harvesting, spectral densities are key quantities. They serve input functions modeling excitation energy transfer dynamics and spectroscopic properties. Herein, recently developed procedure applied to determine pigments minor antenna c...

ABSTRACT The objective of this study was to evaluate the quantum yield and concentrations photosynthetic pigments naturally colored cotton genotypes under irrigation with waters different electrical conductivities foliar applications hydrogen peroxide. design used randomized blocks in a 4 × 3 2 factorial arrangement, corresponding four peroxide - H2O2 (0, 25, 50 75 μM), three fiber (‘BRS Rubi’,...

The photochemical properties of the DNA duplex (dA)(20)·(dT)(20) are compared with those of the parent single strands. It is shown that base pairing increases the probability of absorbing UVA photons, probably due to the formation of charge-transfer states. UVA excitation induces fluorescence peaking at ∼420 nm and decaying on the nanosecond time scale. The fluorescence quantum yield, the fluor...

Photoacclimatory responses of the seagrass Zostera marina in the intertidal and subtidal zones were investigated by measuring chlorophyll a fluorescence parameters, photosynthetic pigments, leaf δ13C values, and shoot morphology in two bay systems. Intertidal plants had higher carotenoid concentrations than subtidal plants to avoid photodamage under excess light conditions during the day. The m...