Hillar Eichelmann

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Finite mesophyll diffusion conductance (g(m) ) significantly constrains net assimilation rate (A(n) ), but g(m) variations and variation sources in response to environmental stresses during leaf development are imperfectly known. The combined effects of light and water limitations on g(m) and diffusion limitations of photosynthesis were studied in(More)
A computer model comprising light reactions, electron–proton transport, enzymatic reactions, and regulatory functions of C3 photosynthesis has been developed as a system of differential budget equations for intermediate compounds. The emphasis is on electron transport through PSII and PSI and on the modeling of Chl fluorescence and 810 nm absorptance(More)
Fast cyclic electron transport (CET) around photosystem I (PS I) was observed in sunflower (Helianthus annuus L.) leaves under intense far-red light (FRL) of up to 200 μmol quanta m−2 s−1. The electron transport rate (ETR) through PS I was found from the FRL-dark transmittance change at 810 and 950 nm, which was deconvoluted into redox states and pool sizes(More)
Oscillations in the rate of photosynthesis of sunflower (Helianthus annuus L.) leaves were induced by subjecting leaves, whose photosynthetic apparatus had been activated, to a sudden transition from darkness or low light to high-intensity illumination, or by transfering them in the light from air to an atmosphere containing saturating CO2. It was found(More)
The global modelling of photosynthesis is based on exact knowledge of the leaf photosynthetic machinery. The capacities of partial reactions of leaf photosynthesis develop at different rates, but it is not clear how the development of photoreactions and the Calvin cycle are co-ordinated. We investigated the development of foliar photosynthesis in the(More)
Parallel measurements of CO2 assimilation, Chl fluorescence and 800 nm transmittance were carried out on intact leaves of wild type and cytochrome b6/f deficient transgenic tobacco grown at two different light intensities and temperatures, with the aim to diagnose processes limiting quantum yield of photosynthesis and investigate their adaptations to growth(More)
The light-dependent control of photosynthetic electron transport from plastoquinol (PQH(2)) through the cytochrome b(6)f complex (Cyt b(6)f) to plastocyanin (PC) and P700 (the donor pigment of Photosystem I, PSI) was investigated in laboratory-grown Helianthus annuus L., Nicotiana tabaccum L., and naturally-grown Solidago virgaurea L., Betula pendula Roth,(More)
Measurements of 810 nm transmittance changes in leaves, simultaneously with Chl fluorescence, CO(2) uptake and O(2) evolution, were carried out on potato (Solanum tuberosum L.) leaves with altered expression of plastidic NADP-dependent malate dehydrogenase. Electron transport rates were calculated: J(C) from the CO(2) uptake rate considering(More)
By recording leaf transmittance at 820 nm and quantifying the photon flux density of far red light (FRL) absorbed by long-wavelength chlorophylls of Photosystem I (PS I), the oxidation kinetics of electron carriers on the PS I donor side was mathematically analyzed in sunflower (Helianthus annuus L.), tobacco (Nicotiana tabacum L.) and birch (Betula pendula(More)
The content of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (Et; EC measured in different-aged leaves of sunflower (Helianthus annuus) and other plants grown under different light intensities, varied from 2 to 75 mmol active sites m. Mesophyll conductance (m) was measured under 1.5% O2, as well as postillumination CO2 uptake(More)