Abbreviations: a*PSII, optical cross section for photosys factor; Chl a, chlorophyll a; Ci, inorganic carbon; CO2, carb anhydrase; ETR, electron transport rate; FIRe, fluorescence Fm′ , light-adapted maximum fluorescence; Fv/Fm, maximum tochemistry in photosystem II; HCO3, bicarbonate; HEPE according to Lavergne and Trissl (1995); MIMS, membran enine dinucleotide phosphate; NaHCO3, sodium bicar...

Ethylene sensitivity of grafted and nongrafted tomato ( Solanum lycopersicum ) seedlings with three to four true leaves was examined. The concentration exogenous ethylene that produced symptoms between 1 10 µL?L –1 regardless grafting. Symptoms exposure included leaf epinasty, decreased maximal photochemical quantum yield photosystem II F v / m ), increased plant height (nongrafted only). Graft...

Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII) inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte) of benthic foraminifera in...

The effect o f K-picrate-18-crown-6 (crown) on the photoelectron transport activity o f beet spinach thylakoid membranes was investigated. Addition o f micromolar concentration o f crown to thylakoid preparation inhibited p-benzoquinone, chloride-indophenol, methyl viologen supported Hill activities maximally by 75 per cent in a concentration dependent manner. However, the photosystem I catalyz...

Photosynthesis is the basic process influencing crop productivity. It can be inhibited by drought. Seven sour cherry genotypes were challenged by drought to assess their photosynthetic efficiency in such conditions. All together with relative water content (RWC) as indicator of plant water status, maximum quantum yield of photosystem II (Fv/Fm) and chlorophyll content (Chl a+b) differentiated i...

A photosynthetic organism is subjected to photo-oxidative stress when more light energy is absorbed than is used in photosynthesis. In the light, highly reactive singlet oxygen can be produced via triplet chlorophyll formation in the reaction centre of photosystem II and in the antenna system. In the antenna, triplet chlorophyll is produced directly by excited singlet chlorophyll, while in the ...

Stomata play a key role in the control of plant water relations and photosynthesis. A rapid non-destructive method to study the stomatal behaviour in aerial parts of plants is important for researchers in plant sciences and agricultural fields. Stomata close in response to drought stress. Stomatal closure causes lower availability of CO2 inside the leaf and thus a decrease in the rate of carbox...

Changes in temperature and daylength trigger physiological and seasonal developmental processes that enable evergreen trees of the boreal forest to withstand severe winter conditions. Climate change is expected to increase the autumn air temperature in the northern latitudes, while the natural decreasing photoperiod remains unaffected. As shown previously, an increase in autumn air temperature ...

The lipids of photosystem II particles, of chloroplasts and leaves are compared in the variegated tobacco mutant N C 95. The mutant differs from other N. tabacum mutants by the phenomenon that it has variegated leaves with green and with yellow-green leaf patches. Chloroplasts from the green leaf areas exhibit photosystem II and photosystem I reactions and have a normal lamellar system with gra...

Z. Naturforsch. 43c, 269-274 (1988); received December 7, 1987 Chlorophyll Fluorescence, S02 , Spinach, Intact Leaves, Calvin Cycle The effects of short-time fumigation (0-60 min) of intact spinach leaves with S02 (2 ppm) on the photosynthetic apparatus were investigated. A rather high S02 concentration was applied to monitor immediate effects on the fluorescence behaviour with the influence of...