In‐field classification of herbicide‐resistant Papaver rhoeas and Stellaria media using an imaging sensor of the maximum quantum efficiency of photosystem II

Weed Research ◽  
2019 ◽  
Vol 59 (5) ◽  
pp. 357-366 ◽  
Author(s):  
A I Linn ◽  
R Mink ◽  
G G Peteinatos ◽  
R Gerhards
Keyword(s):  
Photosystem Ii ◽  
Quantum Efficiency ◽  
Stellaria Media ◽  
Papaver Rhoeas ◽  
Herbicide Resistant ◽  
Imaging Sensor ◽  
Maximum Quantum Efficiency

scholarly journals Quantum efficiency of photosystem II and production of orange under salt stress and nitrogen fertilization

2016 ◽  
Vol 20 (5) ◽  
pp. 434-440 ◽  
Author(s):  
Jônatas R. M. de Sousa ◽  
Hans R. Gheyi ◽  
Marcos E. B. Brito ◽  
Claudivan F. de Lacerda ◽  
Francisco V. da Silva ◽  
...  
Keyword(s):  
Salt Stress ◽  
Photosystem Ii ◽  
Quantum Efficiency ◽  
Saline Water ◽  
Block Design ◽  
Fruit Production ◽  
N Fertilization ◽  
Yield Potential ◽  
Rangpur Lime ◽  
Maximum Quantum Efficiency

ABSTRACT This study aimed to evaluate the salt tolerance of 'Mimo do Céu' orange grafted onto three rootstocks using physiological parameters such as maximum quantum efficiency of photosystem II (PSII) and the production of fruits. It also evaluated the effectiveness of increased nitrogen (N) fertilization in reducing the effects of salt stress. Two concomitant experiments were carried out under controlled conditions, using drainage lysimeters. The Experiment I evaluated the effects of the application of five levels of saline water on three combinations of scion-rootstocks grafted with 'Mimo de Ceu' orange, in a randomized block design with three replicates in a 5 x 3 factorial scheme. The Experiment II evaluated the application of two N levels (100 and 200% of recommendation) in three scion-rootstock combinations irrigated with water of electrical conductivity of 3.0 dS m-1, in a 3 x 2 factorial scheme, with three replicates. The maximum quantum efficiency of PSII was inhibited in citrus plants under salt stress. 'Mimo do Ceu' orange grafted onto 'Common' Rangpur lime has higher yield potential. The increase in N dose did not reduce the deleterious effects of water salinity on fruit production.

scholarly journals The Individual and Combined Effects of the Cyanotoxins, Anatoxin-a and Microcystin-LR, on the Growth, Toxin Production, and Nitrogen Fixation of Prokaryotic and Eukaryotic Algae

Toxins ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 43 ◽  
Author(s):  
Mathias Chia ◽  
Benjamin Kramer ◽  
Jennifer Jankowiak ◽  
Maria Bittencourt-Oliveira ◽  
Christopher Gobler
Keyword(s):  
Nitrogen Fixation ◽  
Photosystem Ii ◽  
Chlorophyll A ◽  
Quantum Efficiency ◽  
Aquatic Ecosystems ◽  
Cyanobacterial Blooms ◽  
Combined Effects ◽  
Phytoplankton Communities ◽  
The Individual ◽  
Maximum Quantum Efficiency

Globally, eutrophication and warming of aquatic ecosystems has increased the frequency and intensity of cyanobacterial blooms and their associated toxins, with the simultaneous detection of multiple cyanotoxins often occurring. Despite the co-occurrence of cyanotoxins such as microcystins and anatoxin-a (ATX) in water bodies, their effects on phytoplankton communities are poorly understood. The individual and combined effects of microcystin-LR (MC-LR) and ATX on the cyanobacteria Microcystis spp., and Anabaena variabilis (a.k.a. Trichormus variabilis), and the chlorophyte, Selenastrum capricornutum were investigated in the present study. Cell density, chlorophyll-a content, and the maximum quantum efficiency of photosystem II (Fv/Fm) of Microcystis cells were generally lowered after exposure to ATX or MC-LR, while the combined treatment with MC-LR and ATX synergistically reduced the chlorophyll-a concentration of Microcystis strain LE-3. Intracellular levels of microcystin in Microcystis LE-3 significantly increased following exposure to MC-LR + ATX. The maximum quantum efficiency of photosystem II of Anabaena strain UTEX B377 declined during exposure to the cyanotoxins. Nitrogen fixation by Anabaena UTEX B377 was significantly inhibited by exposure to ATX, but was unaffected by MC-LR. In contrast, the combination of both cyanotoxins (MC-LR + ATX) caused a synergistic increase in the growth of S. capricornutum. While the toxins caused an increase in the activity of enzymes that scavenge reactive oxygen species in cyanobacteria, enzyme activity was unchanged or decreased in S. capricornutum. Collectively this study demonstrates that MC-LR and ATX can selectively promote and inhibit the growth and performance of green algae and cyanobacteria, respectively, and that the combined effect of these cyanotoxins was often more intense than their individual effects on some strains. This suggests that the release of multiple cyanotoxins in aquatic ecosystems, following the collapse of blooms, may influence the succession of plankton communities.

scholarly journals The Effect of Apple Seed Stratification with Growth Regulators on Breaking the Dormancy of Seeds, the Growth of Seedlings and Chlorophyll Fluorescence

2018 ◽  
Vol 26 (1) ◽  
pp. 37-44
Author(s):  
Krzysztof Górnik ◽  
Mieczysław Grzesik ◽  
Regina Janas ◽  
Edward Żurawicz ◽  
Ewa Chojnowska ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll Content ◽  
Quantum Efficiency ◽  
Growth Regulators ◽  
Germination Rate ◽  
Breeding Cycle ◽  
Content Index ◽  
Seed Stratification ◽  
Growth Of Seedlings ◽  
Maximum Quantum Efficiency

Abstract The aim of the study was to shorten the period of breaking dormancy in apple seeds and to improve the growth of the seedlings of ‘Gold Milenium’, ‘Ligol’ and ‘Szampion’. The whole seeds were removed from fruits directly after the harvest and were subjected to stratification (3 °C for 90 days in darkness) in distilled water or an aqueous solutions of 500 mM salicylic acid (SA), 10−3 M jasmonic acid (JA), gibberellin A3 (GA3) and 6-benzylaminopurine (BAP) at 250 mg·dm−3 and 100 mg·dm−3, respectively. Growth regulators were applied separately or in a mixture containing SA, JA, GA3 and BAP. The germinability and seed germination rate, seedlings growth, chlorophyll content index and the maximum quantum efficiency of Photosystem II (Fv/Fm) were investigated. The obtained results revealed that stratification in water positively affected the dormancy removal in ‘Gold Milenium’, ‘Ligol’ and ‘Szampion’ seeds. Application of SA, GA3, BAP, JA during seed stratification additionally stimulated the seeds’ germination rate as well as the growth of seedlings, index of chlorophyll content and maximum PSII efficiency (Fv/Fm). The most pronounced results were obtained after the seed stratification in GA3 alone or in a mixture containing SA, GA3, BAP and JA. Due to such a treatment, the germination of ‘Ligol’ seeds increased by 40% and they germinated faster in comparison to the control seeds. Such treatments also promoted the growth of seedlings, chlorophyll content and maximum quantum efficiency of Photosystem II (Fv/Fm). The present study indicates that the application of GA3 or the mixture of SA, GA3, BAP and JA during the stratification of seeds is an effective method to increase and accelerate the germination of seeds and juvenile seedlings’ growth in order to shorten the apple breeding cycle. Further studies are needed to optimize the appropriate concentration of growth regulators applied simultaneously during seeds stratification.

scholarly journals Photochemical Efficiency and Recovery of Photosystem II in Grapes After Exposure to Sudden and Gradual Heat Stress

2007 ◽  
Vol 132 (6) ◽  
pp. 764-769 ◽  
Author(s):  
Sorkel Kadir ◽  
Michael Von Weihe ◽  
Kassim Al-Khatib
Keyword(s):  
Heat Treatment ◽  
Heat Stress ◽  
Heat Shock ◽  
Photosystem Ii ◽  
Quantum Efficiency ◽  
Photochemical Efficiency ◽  
Heat Treatments ◽  
Shoot Biomass ◽  
Maximum Quantum Efficiency ◽  
Quantum Efficiency Of Psii

Damage and capacity to recover of photosystem II (PSII) from long exposures to heat stress were investigated in grapes using chlorophyll fluorescence. Two wine grapes, Vitis aestivalis Michx. cv. ‘Cynthiana’ and French-American hybrid ‘Vignoles’ (Vitis L. hybrid), were exposed to a sudden heat shock (SHS) and a gradual heat shock (GHS) at 40/35 °C. After heat stress, plants were moved to a greenhouse to allow PSII to recover from heat treatments. Changes in maximum quantum efficiency of PSII, indicated by the ratio of variable fluorescence and maximum fluorescence (Fv/Fm), were observed after 3, 6, and 12 days of heat stress and after 3, 7, 14, and 21 days recovery periods of damage to PSII. Total leaf area (LA) and leaf, shoot, and root biomass were determined at the end of the experiment. Regardless of the heat treatment, increasing duration of exposure to high temperature caused a decline in Fv/Fm in both cultivars. Heat stress treatments also caused a progressive decline in LA as well as leaf and shoot biomass. Maximum quantum efficiency of PSII was observed after 3 days of exposure in both cultivars, regardless of the heat stress treatment. ‘Vignoles’, however, showed higher PSII photochemical efficiency 12 days after heat exposure. GHS was less detrimental to PSII compared with SHS heat treatment. The damaged PSII of ‘Vignoles’ recovered faster than that of ‘Cynthiana’. A positive relationship was observed between Fv/Fm and LA of plants exposed to heat treatments. Based on Fv/Fm values, this study indicates that PSII of ‘Vignoles’ is more thermostable and can recover faster than that of ‘Cynthiana’ leaves, regardless of the heat treatment. These results suggest that ‘Vignoles’ is generally more heat-tolerant than ‘Cynthiana’ and changes in Fv/Fm ratio under heat stress conditions could be a good indicator for screening heat-resistant grape cultivars.

A Herbicide Resistant Euglena Mutant Carrying a Ser to Thr Substitution at Position 265 in the D1 Protein of Photosystem II

1992 ◽  
Vol 47 (3-4) ◽  
pp. 245-248 ◽  
Author(s):  
A. Aiach ◽  
E. Ohmann ◽  
U. Bodner ◽  
U. Johanningmeier
Keyword(s):  
Amino Acids ◽  
Sequence Analysis ◽  
Photosystem Ii ◽  
D1 Protein ◽  
Inhibitory Effect ◽  
Wild Type ◽  
Rna Sequence ◽  
Herbicide Resistant ◽  
Lower Resistance ◽  
Chlamydomonas Mutants

A herbicide resistant Euglena mutant (MSI) has been obtained by adapting wild type cells to increasing concentrations of DCMU (3-(3′,4′-dichlorophenyl)-1,1-dimethylurea). Lower resistance levels towards DCMU and metribuzin were observed in MSI when compared with Euglena or Chlamydomonas mutants with Ser 264 to Ala substitutions. RNA-sequence analysis identified a Ser to Thr change at position 265 (equivalent to position 264 in other organisms), thus making it possible to compare the influence of amino acids Ser, Ala and Thr at identical positions on the inhibitory effect of structurally different herbicides in the same species.

scholarly journals On the Minimum Quantum Requirement of Photosynthesis

2009 ◽  
Vol 64 (9-10) ◽  
pp. 673-679 ◽  
Author(s):  
Yuzeir Zeinalov
Keyword(s):  
Light Intensity ◽  
Oxygen Evolution ◽  
Quantum Efficiency ◽  
Optical Density ◽  
Dark Respiration ◽  
Linear Part ◽  
Light Curves ◽  
Quantum Requirement ◽  
Light Intensities ◽  
Maximum Quantum Efficiency

An analysis of the shape of photosynthetic light curves is presented and the existence of the initial non-linear part is shown as a consequence of the operation of the non-cooperative (Kok’s) mechanism of oxygen evolution or the effect of dark respiration. The effect of nonlinearity on the quantum efficiency (yield) and quantum requirement is reconsidered. The essential conclusions are: 1) The non-linearity of the light curves cannot be compensated using suspensions of algae or chloroplasts with high (>1.0) optical density or absorbance. 2) The values of the maxima of the quantum efficiency curves or the values of the minima of the quantum requirement curves cannot be used for estimation of the exact value of the maximum quantum efficiency and the minimum quantum requirement. The estimation of the maximum quantum efficiency or the minimum quantum requirement should be performed only after extrapolation of the linear part at higher light intensities of the quantum requirement curves to “0” light intensity

Bicarbonate-Reversible Inhibition of Plastoquinone Reductase in Photosystem II

1993 ◽  
Vol 48 (3-4) ◽  
pp. 251-258 ◽  
Author(s):  
Keyword(s):  
Photosystem Ii ◽  
Active Species ◽  
Current Status ◽  
Ps Ii ◽  
Herbicide Resistant ◽  
Purple Photosynthetic Bacteria ◽  
Slowing Down ◽  
Bicarbonate Effect ◽  
Type Data

Abstract In this paper the current status of the so-called bicarbonate effect is presented. Several chemicals (such as formate, azide, nitrite and nitric oxide) are known to inhibit the two-electron gate of photosystem II (PS II). A remerkable slowing down of QA- reoxidation and an increase in equilibrium [QA- ] have been observed after the second or the subsequent, but not the first, flash when thylakoid membranes are treated with formate, etc. And, significantly, these effects are totally and uniquely reversed upon bicarbonate addition. The current hypothesis is that bicarbonate functions as a proton shuttle that stabilizes the binding niche of QB- and stimulates platoquinol formation. This bicarbonate effect must involve both the D 1 and D 2 proteins since various herbicide-resistant D 1 mutants (e.g., D 1 -S264A , D 1 -L275F), as well as some D 2 mutants (e.g., D 2 -R251S, D 2 -R 233Q) have been found to be differentially sensitive to formate. The D 2-arginine (233, 251) effects are specific since D 2 -R 139H mutant and an­ other mutant in which an extra arginine was inserted, between F 223 and E 224 , behaves like the wild type. Data in the literature suggest that the bicarbonate binding must also involve Fe in the PS II QA-Fe -QB complex. In contrast, the QA-Fe -QB complex and the two-electron gate of both green and purple photosynthetic bacteria, including the M -E 234 G , Q and V mutants, are insensitive to bicarbonate-reversible inhibitors. We will also address the question of the nature of the active species involved and the possible role of bicarbonate in vivo.

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