Photosynthesis

Fedtke, Carl

doi:10.1007/978-3-642-68375-6_3

Cited by 6 publications

(2 citation statements)

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“…2). With each conversion by PGI, there is a probability for hydrogen exchange with the medium of about 30% (Fedtke, 1969; Noltmann, 1972). Thus, if the PGI reaction is in equilibrium, then any deuterium signal at G6P H 2 will be washed out.…”

Section: Discussionmentioning

confidence: 99%

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose

Wieloch,

Holloway-Phillips,

et al. 2024

Preprint

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SummaryUnderstanding isotope fractionation mechanisms is fundamental for analyses of plant ecophysiology and paleoclimate based on tree-ring isotope data.To provide new insights into isotope fractionation, we analysed intramolecular13C discrimination in tree-ring glucose (Δi’,i= C-1 to C-6) and metabolic deuterium fractionation at H1and H2(εmet) combinedly.This dual-isotope approach enabled deconvolution of isotope signals. We found evidence for physiological processes affectingΔ1’ andΔ3’ which respond to air vapour pressure deficit (VPD), and processes affectingΔ1’,Δ2’, andεmetwhich respond to precipitation but notVPD. These relationships exhibit change points dividing a period of homeostasis (1961-1980) from a period of metabolic adjustment (1983-1995). Homeostasis may result from sufficient groundwater availability. Additionally, we foundΔ5’ andΔ6’ relationships with radiation and temperature which are temporally stable and consistent with previously proposed isotope fractionation mechanisms.Based on the multitude of climate covariables, intramolecular carbon isotope analysis has an extraordinary potential for climate reconstruction. While isotope fractionation beyond leaves is usually considered to be constant, we propose significant parts of the carbon and hydrogen isotope variation in tree-ring glucose originate in stems (precipitation-dependent signals). As basis for follow-up studies, we propose mechanisms introducingΔ1’,Δ2’,Δ3’, andεmetvariability.

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Section: Discussionmentioning

confidence: 99%

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose

Wieloch,

Holloway-Phillips,

et al. 2024

Preprint

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“…no ii tc j.i inon i. • A c u u J • Plant material and growth conditions at PS II (Fedtke 1982). It is used in faba bean and is 6 the most common selective herbicide recommended Field experiments were done in two experimental for Mediterranean areas.…”

Section: Faba Bean {Vicia Faba L) Is the Most Importantmentioning

confidence: 99%

Nitrogenase activity, nodulation and seed production inVicia fabaas affected by methabenzthiazuron

1996

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The effects of recommended application rates of the herbicide methabenzthiazuron (MBT) (2-5 and 4 kg ha" 1 ) on vegetative growth, nodulation and N 2 fixation in faba bean plants were studied in the field at Barcelona during 1990 and 1991. Nodulation, specific nitrogenase activity (SNA) of excised nodules, dry weight of plants and seed nitrogen content at harvest were compared in MBT-treated, hand-weeded (HW) and control plants. In 1990 the higher MBT application (4 kg ha" 1 ) caused a decrease in nodulation and acetylene reduction activity (ARA) per plant during the mid-period of pod-fill, and also in vegetative growth, seed production and N content of seeds, whereas the lower rate (2-5 kg ha" 1 ) did not have a significant effect on any of these factors. However, in 1991, growth and herbicide effects were different from those in the previous year. No inhibitory effect of MBT on nodulation, SNA or ARA per plant was observed and vegetative growth, seed production and N content of seeds were not significantly different from those of plants from HW plots. In 1991, both 4 kg ha" 1 of MBT and the HW treatment caused a stimulatory effect on seed N recovery and yield compared to control plants. Rates of ARA per plant at late pod-fill were positively related to N recovery by seeds. These differences could have been due to the low rainfall in 1990, which may have permitted MBT to remain in the soil for a longer period and to inhibit N fixation and plant growth in the Vicia faba crop.

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Herbicides, Inhibitors of Photosynthesis at PhotosystemII

Oettmeier

2002

Encyclopedia of Agrochemicals

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Herbicides of photosystem II inhibit the reduction of plastoquinone at the secondary quinone acceptor site ( Q B ‐site) and its subsequent reoxidation at the cytochrome b 6 / f ‐complex. The Q B ‐site is located at the photosystem II reaction center protein called D1. When the reduction of plastoquinone is blocked by the herbicide, light‐induced charge separation leads to recombination processes that via a chlorophyll triplet state generate reactive oxygen species. These will cause extensive damage in photosystem II and eventually kill the plant. Amino acids involved in herbicide binding can be identified in three ways: 1) by comparison with the well‐known X‐ray structure of the bacterial photosynthetic reaction center, 2) by photoaffinity labeling with photolabile radioactive analogs of herbicides, and 3) by analysis of the herbicide binding in herbicide‐resistant mutants of plants, algae, and cyanobacteria with known mutations in the D1 protein. Herbicides of photosystem II belong to the following chemical classes: s ‐triazines, triazinones, uracils, ureas, phenylcarbamates, anilides, cyanophenols, dinitrophenols, and some chemicals that do not belong to these classes, like bentazon, fluoromidine, pyrazon, and pyridate.

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Photosynthesis

Cited by 6 publications

References 422 publications

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose

Nitrogenase activity, nodulation and seed production inVicia fabaas affected by methabenzthiazuron

Herbicides, Inhibitors of Photosynthesis at PhotosystemII

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Photosynthesis

Cited by 6 publications

References 422 publications

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular13C and deuterium abundances inPinus nigratree-ring glucose

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular13C and deuterium abundances inPinus nigratree-ring glucose

Nitrogenase activity, nodulation and seed production inVicia fabaas affected by methabenzthiazuron

Herbicides, Inhibitors of Photosynthesis at PhotosystemII

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New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose

New insights into the mechanisms of plant isotope fractionation from combined analysis of intramolecular¹³C and deuterium abundances inPinus nigratree-ring glucose