Distribution and Effects of Bentazon in Crop Plants and Weeds

1982 ◽  
Vol 37 (10) ◽  
pp. 889-897 ◽  
Author(s):  
H. K. Lichtenthaler ◽  
D. Meier ◽  
G. Retzlaff ◽  
R. Hamm
Keyword(s):  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Crop Plants ◽  
Light Conditions ◽  
Low Light ◽  
Tolerant Plants ◽  
Variable Chlorophyll Fluorescence ◽  
Pigment Ratios ◽  
Kautsky Effect ◽  
Uptake And Transport

Abstract The inhibition of photosynthetic CO2-assimilation and of the variable chlorophyll fluorescence as well as uptake and transport of 14C-labelled bentazon and the possibilities for a herbicideinduced shade-type modification of the photosynthetic apparatus were investigated in bentazonsensitive weeds (Galium, Sinapis, Raphanus) and in the tolerant crop plants wheat and maize.1. In weeds the depression of photosynthetic CO2-assimilation is irreversible, whereas tolerant plants recover due to the metabolization of the active herbicide.2. A lower rate of uptake and transport of bentazon associated with its fast metabolization is the reason for the tolerance of crop plants towards bentazon.3. The transport of [14C]bentazon proceeds in the tracheary elements of the xylem. Uptake and transport of bentazon in the weeds are light dependent.4. The loss of variable fluorescence (Kautsky effect) in the leaves after root application o f bentazon proceeds much faster at high-light than at low light conditions and confirms the light-dependency of the bentazon transport.5. In the sensitive dicot weeds bentazon not only inhibits photosynthetic electron flow and depresses CO2-fixation but also induces the formation of shade-type chloroplasts which are less efficient in photosynthetic quantum conversion. This bentazon-induced modification of the photosynthetic apparatus (e.g. changes in ultrastructure, pigment ratios, and levels of chloro-phyll-proteins) contributes to the effectiveness of bentazon as a herbicide.

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

Über die prompte und verzögerte Fluoreszenz des Chlorophylls während der Photomorphogenese des photosynthetischen Apparates grüner Pflanzen / The Prompt and Delayed Light Emission of Chlorophyll During Photomorphogenesis of the Photosynthetic Apparatus of Green Plants

1972 ◽  
Vol 27 (10) ◽  
pp. 1202-1204 ◽  
Author(s):  
Robert Bauer ◽  
Ulrich F. Franck
Keyword(s):  
Light Emission ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Anaerobic Conditions ◽  
Ps Ii ◽  
Delayed Light Emission ◽  
Ps I ◽  
Active Electron ◽  
Induced Changes ◽  
Kautsky Effect

The greening process of etiolated bean and maize leafs was followed by measuring the prompt and delayed light emission of chlorophyll. Above all it was concluded that the development of photosynthetic Systems I and II could be observed by studying the formation of the Kautsky -effect. First light-induced changes in the chlorophyll fluorescence intensity do not occur until 2,5 h of irradiation. It could be shown that they reflect the function of PS II reaction centers and under anaerobic conditions the electron flow between PS II and PS I. Full active electron flow from water to NADP is first to presume with the appearence of all characteristics of the Kautsky -effect (O—I—D—P curve at 3 h of irradiation).

scholarly journals Photosynthesis acclimation under severely fluctuating light conditions allows faster growth of diatoms compared with dinoflagellates

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lu Zhou ◽  
Songcui Wu ◽  
Wenhui Gu ◽  
Lijun Wang ◽  
Jing Wang ◽  
...  
Keyword(s):  
Red Tide ◽  
Skeletonema Costatum ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Specific Inhibitor ◽  
Dynamic Environments ◽  
Thalassiosira Pseudonana ◽  
Light Conditions ◽  
Photosynthetic Electron Flow ◽  
Fluctuating Light

Abstract Background Diatoms contribute 20% of the global primary production and are adaptable in dynamic environments. Diatoms always bloom earlier in the annual phytoplankton succession instead of dinoflagellates. However, how diatoms acclimate to a dynamic environment, especially under changing light conditions, remains unclear. Results We compared the growth and photosynthesis under fluctuating light conditions of red tide diatom Skeletonema costatum, red tide dinoflagellate Amphidinium carterae, Prorocentrum donghaiense, Karenia mikimotoi, model diatom Phaeodactylum tricornutum, Thalassiosira pseudonana and model dinoflagellate Dinophycae Symbiodinium. Diatoms grew faster and maintained a consistently higher level of photosynthesis. Diatoms were sensitive to the specific inhibitor of Proton Gradient Regulation 5 (PGR5) depending photosynthetic electron flow, which is a crucial mechanism to protect their photosynthetic apparatus under fluctuating light. In contrast, the dinoflagellates were not sensitive to this inhibitor. Therefore, we investigate how PGR5 functions under light fluctuations in the model diatom P. tricornutum by knocking down and overexpressing PGR5. Overexpression of PGR5 reduced the photosystem I acceptor side limitation (Y (NA)) and increased growth rate under severely fluctuating light in contrast to the knockdown of PGR5. Conclusion Diatoms acclimatize to fluctuating light conditions better than dinoflagellates. PGR5 in diatoms can regulate their photosynthetic electron flow and accelerate their growth under severe light fluctuation, supporting fast biomass accumulation under dynamic environments in pioneer blooms.

scholarly journals Response of Photosynthetic Apparatus to Different Irradiance in Flag Leaves of High-Yielding Winter Wheat PH01-35 Grown under Low Light Conditions

2009 ◽  
Vol 35 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Feng GUO ◽  
Yan-Yan QU ◽  
Chang-Peng XIN ◽  
Yan LIANG ◽  
Xue LIANG ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Photosynthetic Apparatus ◽  
Light Conditions ◽  
Low Light ◽  
Flag Leaves

scholarly journals Compensation Mechanism of the Photosynthetic Apparatus in Arabidopsis thaliana ch1 Mutants

2020 ◽  
Vol 22 (1) ◽  
pp. 221
Author(s):  
Joanna Wójtowicz ◽  
Adam K. Jagielski ◽  
Agnieszka Mostowska ◽  
Katarzyna B. Gieczewska
Keyword(s):  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Protein Composition ◽  
Mrna Levels ◽  
Chlorophyll B ◽  
Low Light ◽  
Plant Acclimation ◽  
Chlorophyll B Deficiency ◽  
Composition Changes

The origin of chlorophyll b deficiency is a mutation (ch1) in chlorophyllide a oxygenase (CAO), the enzyme responsible for Chl b synthesis. Regulation of Chl b synthesis is essential for understanding the mechanism of plant acclimation to various conditions. Therefore, the main aim of this study was to find the strategy in plants for compensation of low chlorophyll content by characterizing and comparing the performance and spectral properties of the photosynthetic apparatus related to the lipid and protein composition in four selected Arabidopsis ch1 mutants and two Arabidopsis ecotypes. Mutation in different loci of the CAO gene, viz., NW41, ch1.1, ch1.2 and ch1.3, manifested itself in a distinct chlorina phenotype, pigment and photosynthetic protein composition. Changes in the CAO mRNA levels and chlorophyllide a (Chlide a) content in ecotypes and ch1 mutants indicated their significant role in the adjustment mechanism of the photosynthetic apparatus to low-light conditions. Exposure of mutants with a lower chlorophyll b content to short-term (1LL) and long-term low-light stress (10LL) enabled showing a shift in the structure of the PSI and PSII complexes via spectral analysis and the thylakoid composition studies. We demonstrated that both ecotypes, Col-1 and Ler-0, reacted to high-light (HL) conditions in a way remarkably resembling the response of ch1 mutants to normal (NL) conditions. We also presented possible ways of regulating the conversion of chlorophyll a to b depending on the type of light stress conditions.

scholarly journals Perceptually based tone mapping for low-light conditions

2011 ◽  
Vol 30 (4) ◽  
pp. 1-10 ◽  
Author(s):  
Adam G. Kirk ◽  
James F. O'Brien
Keyword(s):  
Tone Mapping ◽  
Light Conditions ◽  
Low Light

Non-Invasive Monitoring of the Light-Induced Cyclic Photosynthetic Electron Flow during Cold Hardening in Wheat Leaves

2006 ◽  
Vol 61 (9-10) ◽  
pp. 734-740 ◽  
Author(s):  
Simona Apostol ◽  
Gabriella Szalai ◽  
László Sujbert ◽  
Losanka P. Popova ◽  
Tibor Janda
Keyword(s):  
Winter Wheat ◽  
Electron Flow ◽  
Wheat Variety ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Light Conditions ◽  
Non Invasive ◽  
Photosynthetic Electron Flow ◽  
Temperature Hardening ◽  
Wheat Leaves

AbstractThe effect of irradiance during low temperature hardening was studied in a winter wheat variety. Ten-day-old winter wheat plants were cold-hardened at 5 °C for 11 days under light (250 μmol m-2 s-1) or dark (20 μmol m-2 s-1) conditions. The effectiveness of hardening was significantly lower in the dark, in spite of a slight decrease in the Fv/Fm chlorophyll fluorescence induction parameter, indicating the occurrence of photoinhibition during the hardening period in the light. Hardening in the light caused a downshift in the far-red induced AG (afterglow) thermoluminescence band. The faster dark re-reduction of P700+, monitored by 820-nm absorbance, could also be observed in these plants. These results suggest that the induction of cyclic photosynthetic electron flow may also contribute to the advantage of frost hardening under light conditions in wheat plants.

scholarly journals Olfactory acuity in theropods: palaeobiological and evolutionary implications

2008 ◽  
Vol 276 (1657) ◽  
pp. 667-673 ◽  
Author(s):  
Darla K Zelenitsky ◽  
François Therrien ◽  
Yoshitsugu Kobayashi
Keyword(s):  
Olfactory Bulb ◽  
Cerebral Hemisphere ◽  
Home Ranges ◽  
Light Conditions ◽  
Low Light ◽  
Olfactory Bulbs ◽  
Theropod Dinosaurs ◽  
Olfactory Acuity ◽  
Predicted Values ◽  
Omnivorous Diet

This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.

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