scholarly journals PYRACLOSTROBIN PRESERVES PHOTOSYNTHESIS IN ARABICA COFFEE PLANTS SUBJECTED TO WATER DEFICIT

2020 ◽  
Vol 28 ◽  
pp. 109-119
Author(s):  
Anelisa Figueiredo Peloso ◽  
Sandro Dan Tatagiba ◽  
Francisco José Teixeira Amaral ◽  
Paulo César Cavatte ◽  
José Eduardo Macedo Pezzopane
Keyword(s):  
Quantum Yield ◽  
Water Deficit ◽  
Chlorophyll A ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Photosynthetic Performance ◽  
Effective Quantum Yield ◽  
Fluorescence Maximum ◽  
Common Strategy ◽  
Coffee Plants

The objective of this study was to investigate the effect of pyraclostrobin on the photosynthetic performance of rabica coffee plants subjected or not to a water deficit, using the parameter of gas exchange (net CO2 assimilation, stomatal conductance, transpiration rate, and internal CO2 concentration and nocturnal respiration), chlorophyll fluorescence a parameters (minimum fluorescence, maximum fluorescence, maximum quantum yield of photosystem II, effective quantum yield of PSII, quantum yield of regulated energy dissipation and quantum yield dissipation non-regulated) as well as the concentrations of chloroplast pigments. In the plants maintained without water deficit, pyraclostrobin did not cause any alteration on the parameters of chlorophyll a fluorescence; however, it contributed to an increase in the level of chlorophyll a + b, CO2 assimilation and CO2 influx for the carboxylation sites of the stroma. Decreases in nocturnal respiration in plants treated with pyraclostrobin, submitted or not to water deficit seems to be a common strategy in reducing energy waste in the maintenance metabolism. Under water deficit, pyraclostrobin contributed to increase the photochemical yield, enabling plants to effectively prevent the capture, use and dissipation of light energy.

scholarly journals Photosynthetic responses of young cashew plants to varying environmental conditions

2005 ◽  
Vol 40 (8) ◽  
pp. 735-744 ◽  
Author(s):  
Rogéria Pereira de Souza ◽  
Rafael Vasconcelos Ribeiro ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira ◽  
Joaquim Albenísio Gomes da Silveira
Keyword(s):  
Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Effective Quantum Yield ◽  
Water Losses ◽  
Controlled Conditions

The aim of this study was to characterize gas exchange responses of young cashew plants to varying photosynthetic photon flux density (PPFD), temperature, vapor-pressure deficit (VPD), and intercellular CO2 concentration (Ci), under controlled conditions. Daily courses of gas exchange and chlorophyll a fluorescence parameters were measured under natural conditions. Maximum CO2 assimilation rates, under optimal controlled conditions, were about 13 mmol m-2 s-1 , with light saturation around 1,000 mmol m-2 s-1. Leaf temperatures between 25ºC and 35ºC were optimal for photosynthesis. Stomata showed sensitivity to CO2, and a closing response with increasing Ci. Increasing VPD had a small effect on CO2 assimilation rates, with a small decrease above 2.5 kPa. Stomata, however, were strongly affected by VPD, exhibiting gradual closure above 1.5 kPa. The reduced stomatal conductances at high VPD were efficient in restricting water losses by transpiration, demonstrating the species adaptability to dry environments. Under natural irradiance, CO2 assimilation rates were saturated in early morning, following thereafter the PPFD changes. Transient Fv/Fm decreases were registered around 11h, indicating the occurrence of photoinhibition. Decreases of excitation capture efficiency, decreases of effective quantum yield of photosystem II, and increases in non-photochemical quenching were consistent with the occurrence of photoprotection under excessive irradiance levels.

scholarly journals Fire Blight Management: Physiological Assessment of Cultural Control By Pruning in Pear Orchards

2020 ◽  
Vol 66 (3) ◽  
pp. 128-136
Author(s):  
Rafael J. Mendes ◽  
Nuno Mariz-Ponte ◽  
Cristiana V. Correia ◽  
Maria Celeste Dias ◽  
Miguel Leão De Sousa ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Gas Exchange ◽  
Fire Blight ◽  
Soluble Sugars ◽  
Photosynthetic Performance ◽  
Cultural Control ◽  
Photosynthetic Parameters ◽  
Effective Quantum Yield ◽  
Total Soluble Sugars ◽  
Bisphosphate Carboxylase

AbstractThe aim of this work was to evaluate the photosynthetic performance of Pear trees (cv. ‘Rocha’) infected with Erwinia amylovora, three months after suffering a pruning of infected branches (P-trees) compared with asymptomatic trees (C-trees) of the same orchard. Three months after pruning, P-trees looked healthy and were negative for the presence of E. amylovora. In September of 2018, fully expanded leaves of both P- and C- trees were sampled and analysed for photosynthetic parameters related to chlorophyll a fluorescence and gas exchange, alongside with pigments, total soluble sugars, starch, and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. No significant differences were found in chlorophyll and carotenoids levels, but anthocyanins significantly decreased in P-trees. Also, despite the maximum quantum yield (Fv/Fm) significantly decreased in P-trees, the effective quantum yield of the PSII was maintained, paralleled with no changes in gas exchange parameters (PN, gs, Ci, E, iWUE, PN/gs), nor in RuBisCO relative content. Finally, the maintenance of the levels of total soluble sugars and starch also supports that the photosynthetic performance of P-trees, three months after pruning, reached values similar to those of the C-trees, contributing to the normal development and ripening of the fruit. Data support that pruning represents a reliable control measure against this quarantine pathogen. This work is the first evaluation of pruning in fire blight management regarding carbon metabolism in P. communis trees.

scholarly journals Half-Sib Lines of Pedunculate Oak (Quercus robur L.) Respond Differently to Drought Through Biometrical, Anatomical and Physiological Traits

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 153 ◽  
Author(s):  
Erna Vastag ◽  
Claudia Cocozza ◽  
Saša Orlović ◽  
Lazar Kesić ◽  
Milena Kresoja ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Fluorescence Quenching ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Quercus Robur ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Drought Tolerant ◽  
Selection Of

Quercus robur L. is one of the most valued tree species of deciduous temperate forests. However, in the last decade, serious oak declines and loss of adaptation plasticity have been reported throughout Europe as a consequence of drought. Therefore, the aim of the present study was to define the adaptation potential of five Q. robur half-sib lines from the UNESCO Biosphere Reserve Mura-Drava-Danube to drought, using physiological, anatomical and biometrical traits. Half-sib lines that exhibited drought tolerance had particular suites of trait expression regarding biometrical traits (seedling height, root length, root to shoot ratio of dry mass and specific leaf area), leaf stomatal traits (stomatal density per mm2, stomata guard cell length and width, stomatal aperture length and width) and leaf structural traits (adaxial epidermis thickness, palisade parenchyma thickness, spongy parenchyma thickness, lamina thickness). All of the observed parameters of chlorophyll a fluorescence were shown to be good indicators of short-term and severe drought. For the selection of drought-tolerant half-sib lines, all studied chlorophyll a fluorescence parameters associated with the heat dissipation of light energy (coefficient of non-photochemical quenching, quantum yield of regulated energy dissipation, Stern-Volmer type non-photochemical fluorescence quenching) and one parameter related to photochemical dissipation of light energy (effective quantum yield (efficiency) of PS II photochemistry) were proven to be suitable. On the other hand, the coefficient of photochemical quenching, coefficient of photochemical fluorescence quenching assuming interconnected photosystem II antennae and electron transport rate were not suitable for distinguishing the different responses of the studied half-sib lines under drought. The importance of results of the present study is in the selection of drought-tolerant Q. robur half-sib lines for future reforestation programs, particularly in protected areas with sensitive forest management and restricted activities for mitigation of the adverse effects of climate changes.

scholarly journals Comparative stomatal conductance and chlorophyll a fluorescence in leaves vs. fruits of the cerrado legume tree, Dalbergia miscolobium

2004 ◽  
Vol 16 (2) ◽  
pp. 89-93 ◽  
Author(s):  
José Pires de Lemos Filho ◽  
Rosy Mary dos Santos Isaias
Keyword(s):  
Water Vapor ◽  
Stomatal Conductance ◽  
Quantum Yield ◽  
Chlorophyll A ◽  
Chlorophyll A Fluorescence ◽  
Electron Transport Rate ◽  
Early Morning ◽  
Effective Quantum Yield ◽  
Quantum Yield Of Psii ◽  
Chronic Photoinhibition

The aim of this study was to compare water vapor conductance and chlorophyll a fluorescence between leaflets and fruits of Dalbergia miscolobium, the Jacaranda tree. The frequency of stomata on the leaflets was 20 times higher than that observed on the fruits, and this was related with the lower conductance of the fruits in comparison with the leaflets. The potential quantum yield of PSII (Fv /Fmax) was significantly lower in fruits than in leaflets. The Fv /Fmax values for leaflets increased to over 0.8 during the afternoon, indicating the occurrence of dynamic photoinhibition. In contrast, Fv /Fmax values for fruits remained low even at early morning, indicating the occurrence of chronic photoinhibition. The maximum values of effective quantum yield (deltaF/F'm), and of the apparent electron transport rate (ETRmax) were higher in leaflets than in fruits. It was concluded that, like other green tissues, the pericarp of D. miscolobium was photosynthetically active, and therefore can contribute to the maintenance of the fruits and/or to the development of the seeds.

scholarly journals Growth and photosynthesis of Lemna minor L. exposed to different light conditions and sucrose supplies

2013 ◽  
Vol 72 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Željka Vidaković-Cifrek ◽  
Sonja Sorić ◽  
Marija Babić
Keyword(s):  
Quantum Yield ◽  
Lemna Minor ◽  
Action Spectrum ◽  
Photosynthetic Performance ◽  
Light Sources ◽  
Effective Quantum Yield ◽  
Light Conditions ◽  
Promotive Effect ◽  
Sucrose Supply ◽  
Quantum Yield Of Psii

Abstract Duckweed (Lemna minor L.) is a model plant suitable for investigation into plant physiology, biochemistry and ecotoxicology. Depending on the type of the experiment, duckweed is cultivated on different nutrient media under various chamber conditions. In our work, duckweed was cultivated on Pirson-Seidel’s nutrient solution supplemented with 5, 7.5 or 10 g L-1 sucrose under cool white (CW) or Gro-Lux (GL) light sources. When different light sources and sucrose supplies are compared, a significant stimulative effect of GL light on duckweed grown on 7.5 and 10 g L-1 sucrose was seen to start on day 9. Considering photosynthetic performance the results showed that there were no significant differences in maximum quantum yield of PSII (Fv/Fm) after 7 and 16 days of exposure, regardless of light source and sucrose supply. Effective quantum yield of PSII (ΦPSII) decreased only after 16 days of exposure to 5 g L-1 sucrose under CW light. The higher growth rate and photosynthetic performance in plants exposed to GL light is a consequence of its spectral distribution resembling the action spectrum of photosynthesis. Furthermore, enhanced growth noticed in plants cultivated on higher sucrose contents (7.5 and 10 g L-1) indicated the promotive effect of sucrose in plants grown under low light conditions.

scholarly journals Gas exchanges and photosynthetic pigments of ‘Tommy Atkins’ mango as a function of fenpropimorph

2022 ◽  
Vol 26 (4) ◽  
pp. 239-247
Author(s):  
Daniel de A. Carreiro ◽  
Renata A. e Amariz ◽  
Luciana G. Sanches ◽  
Jackson T. Lobo ◽  
Vespasiano B. de Paiva Neto ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Photosynthetic Pigments ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Production Cycle ◽  
Plant Canopy ◽  
Total Chlorophyll ◽  
Gas Exchanges ◽  
Internal Co2 ◽  
Semi Arid Region

ABSTRACT The objective of the present study was to evaluate the influence of the application of fenpropimorph and paclobutrazol on gas exchanges and photosynthetic pigments of ‘Tommy Atkins’ mango grown in the semi-arid region in different evaluation periods. Two experiments were carried out in ‘Tommy Atkins’ mango orchards in the first production cycle between September and December 2018 (first experiment) and between September and December 2019 (second experiment) in Petrolina, PE, Brazil. The experimental design adopted was randomized blocks in split plots in time, 4 × 4 + 1, with four replicates. The plots corresponded to the concentrations of fenpropimorph: 0, 0.7, 1.0, and 1.3 g per linear meter of plant canopy diameter plus the additional paclobutrazol treatment (1 g per linear meter of plant canopy diameter), and the subplots corresponded to the evaluation dates (0, 30, 60, and 90 days after the first application of treatments). The following traits were evaluated: CO2 assimilation rate, stomatal conductance, internal CO2 concentration, transpiration, water use efficiency, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. The fenpropimorph dose of 1.3 g per linear meter of plant canopy promotes a higher rate of CO2 assimilation; however, paclobutrazol was more effective in the accumulation of chlorophyll a and total chlorophyll, and the use of fenpropimorph did not interfere in the concentration of photosynthetic pigments.

scholarly journals Physiological changes in soybean cultivated with soil remineralizer in the Cerrado under variable water regimes

2021 ◽  
Vol 56 ◽  
Author(s):  
Lucas Felisberto Pereira ◽  
Walter Quadros Ribeiro Junior ◽  
Maria Lucrécia Gerosa Ramos ◽  
Nicolas Zendonadi dos Santos ◽  
Guilherme Filgueiras Soares ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Grain Quality ◽  
Stomatal Closure ◽  
Co2 Concentration ◽  
Mean Value ◽  
Effective Quantum Yield ◽  
Mica Schist ◽  
Water Regimes ◽  
Internal Co2 ◽  
And Control

Abstract: The objective of this work was to evaluate the influence of the soil remineralizer fine-graded mica schist (FMS) on soybean (Glycine max) physiology, yield, and grain quality under different water regimes (WRs) in the Brazilian Cerrado. The experiment was conducted under field conditions for two years, using four WRs and three treatments: mica schist, conventional fertilization, and control. In 2017 and 2018, the following WRs were evaluated: WR1, WR2, WR3, and WR4, corresponding to a mean value of 100, 65, 44, and 28% of crop evapotranspiration replacement, respectively. Photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, effective quantum yield of photosystem II (PSII) (Fv’/Fm’), quantum yield (PSII) (ᶲFSII), and electron transport rate reduced as a function of the advanced phenological stage of soybean and the reduction in WR. Grain quality was only affected by the WR. The mica schist was statistically similar to conventional fertilization and the control in 2017 and 2018. Yield decreased due to the anticipation of soybean phenological age and WR, but there were no differences between the three treatments in 2017 and 2018. The reduction in soybean yield is attributed to stomatal closure, loss of photoprotective capacity, and damage to the photosynthetic machinery caused by drought.

scholarly journals The Effects of Environmental Contaminants on Freshwater Cyanobacteria

2021 ◽  
Author(s):  
◽  
Jenna Mumford
Keyword(s):  
New Zealand ◽  
Quantum Yield ◽  
Chlorophyll A ◽  
Environmental Conditions ◽  
Algal Blooms ◽  
Photosynthetic Performance ◽  
Pigment Content ◽  
Maximum Quantum Yield ◽  
Screening Assay ◽  
Significant Difference

<p>Cyanobacteria are photosynthetic prokaryotes with a cosmopolitan distribution and are key contributors to Earth’s primary production. In favourable conditions, some taxa have the ability to form dense algal blooms. When blooms are created by toxin-producing strains they can become a public health threat and may lead to deaths of wild and domestic animals. Different species and strains respond differently to environmental conditions and contaminants, and this thesis investigates the impacts of natural (microcystin, a hepatotoxic cyanotoxin) and anthropogenic (glyphosate) contaminants on cyanobacteria.  Some non-microcystin-producing cyanobacteria have the ability to sequester microcystin, one of them being the strain Cuspidothrix issatschenkoi CAWBG02, and the reason for this ability is unknown. This strain was supplemented with microcystin in a range of environmental conditions (temperature/light intensity combinations) to determine any impacts on fitness by measuring photosynthetic performance, growth, and pigment content (chlorophyll-a and phycocyanin). Microcystin supplementation at a concentration of 25 μg L-1 did not have an effect on growth or pigment content in C. issatschenkoi, and photosynthetic performance was also largely unaffected. Based on the results from this thesis, C. issatschenkoi does not acquire competitive advantages from microcystin sequestration due to the lack of effects on growth and photosynthetic functioning. Previous research has suggested that microcystin is used to suppress competitors, and a 33% decrease in maximum quantum yield was detected in one environmental condition (low temperature, intermediate light), however, there was no significant difference in all of the other conditions used. Therefore, the results from this study do not support the idea that microcystin is used to suppress competitors. Microcystin sequestration may be more beneficial to non-producing-strains within the same species as the toxin-producer (e.g. non-toxic M. aeruginosa).  Glyphosate and MCPA are two of the most commonly used herbicides in New Zealand and globally. These herbicides enter waterways through leaching and come into contact with non- target species. To determine whether these herbicides have an effect on freshwater cyanobacteria in New Zealand, a screening assay was carried out on fourteen strains. Further, the impacts on pigment content (chlorophyll-a and phycocyanin), growth, and photosynthetic performance in two toxic (Nodularia spumigena, Microcystis aeruginosa) and two non-toxic (Dolichospermum lemmermannii, Microcystis wesenbergii) strains were quantified. Growth rates were not impacted by MCPA in any of the fourteen cyanobacterial strains. Glyphosate impacted growth in seven of the fourteen strains, and response differed between strains even within a single species. In general, strains employing a colonial growth strategy were more tolerant to glyphosate in the screening assay. N. spumigena and M. wesenbergii were unaffected by glyphosate at the concentrations used in the functional analysis, and D. lemmermannii had decreased photosynthetic performance from glyphosate. Intermediate concentrations of glyphosate resulted in promotion of PSII functioning in M. aeruginosa, and high concentrations inhibited maximum quantum yield. The lack of significant impacts on M.wesenbergii and N. spumigena, as well as negative effects of PSII functioning in D. lemmermannii, suggest that glyphosate contamination in freshwaters may benefit toxic M. aeruginosa more than competing toxic and non-toxic species or strains.</p>

scholarly journals The Effect of Water Deficit and Nitrogen on the Antioxidant Enzymes’ Activity and Quantum Yield of Barley ( Hordeum vulgare L.)

2014 ◽  
Vol 42 (2) ◽  
pp. 398-404 ◽  
Author(s):  
Arezu MOVLUDI ◽  
Ali EBADI ◽  
Soodabeh JAHANBAKHSH ◽  
Mahdi DAVARI ◽  
Ghasem PARMOON
Keyword(s):  
Antioxidant Enzymes ◽  
Quantum Yield ◽  
Grain Yield ◽  
Water Deficit ◽  
Chlorophyll A ◽  
Proline Content ◽  
Carotenoid Content ◽  
Mild Stress ◽  
Chlorophyll B ◽  
Enzymes Activity

The effects of water deficit and nitrogen fertilizer were studied on antioxidant enzymes activity and quantum yield of barley. An experiment carried out in greenhouse in factorial subject based on a completely randomized design with three replications. Irrigation schedules imposed at three levels of 85%, 60% and 35% field capacity (FC), and nitrogen were applied in quantities of 40, 80 and 120 kg N ha-1. We determined Catalase (CAT), Peroxidase (POX) Polyphenol oxidase (PPO) activities, proline, chlorophyll and carotenoid content, quantum yield and grain yield. The results showed that severe stress (35% FC) increased the activities of CAT, POX and PPO enzymes and proline content, whereas the carotenoids, chlorophyll a and chlorophyll b decreased. Water deficiency caused the reduction in the quantum yield and the grain yield by 34%. Application of 80 kg of N during stress treatments resulted in higher enzyme activity and proline content. High amount of nitrogen reduced carotenoids, chlorophyll a, chlorophyll b, and in contrast, enhanced quantum yield. Application of 120 kg N ha-1 increased the yield up to 37% under mild stress (35% FC). Correlation coefficient and path coefficient showed that, grain yield was affected directly by amount of carotenoids and quantum yield.

scholarly journals RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO

2018 ◽  
Vol 31 (1) ◽  
pp. 9-18
Author(s):  
ALANA CRISTINA FERREIRA ARAÚJO ◽  
JOÃO CARLOS MADALÃO ◽  
ADRIANO JAKELAITIS ◽  
ALAN CARLOS COSTA ◽  
GABRIEL MARTINS ALMEIDA
Keyword(s):  
Quantum Yield ◽  
Chlorophyll A ◽  
Dry Matter ◽  
Additional Treatment ◽  
Photosynthetic Characteristics ◽  
Paspalum Notatum ◽  
Effective Quantum Yield ◽  
Chlorophyll B ◽  
Total Chlorophyll ◽  
Forage Species

ABSTRACT Some forages release allelopathic substances into the environment, and may prevent consortium with arboreal species in pastures. The objective of this work was to evaluate photosynthetic characteristics of pequizeiro plants (hereafter pequi) influenced by concentrations of residues of the forage species Urocholoa decumbens, Melinis minutiflora and Paspalum notatum. The treatments consisted of pequi cultivation under aerial residues of the three forage species mixed to the substrate in four concentrations (1, 2, 3 and 4% mass/mass), plus an additional treatment (comparative control) with pequi cultivated on the substrate without waste. The following parameters were evaluated: photosynthetic rate, stomatal conductance, transpiration rate, relationship between internal and external CO2 concentration (Ci/Ca), maximum quantum yield, effective quantum yield of FS II, electron transport rate, nonchemical quenching and chlorophyll index, concerning the content of chlorophyll a, b and total in pequi plants at 50 and 100 days after transplanting (DAT), and the relative production of dry matter at 100 DAT. At 50 DAT, the following photosynthetic variables were affected in pequi plants: A, gs, chlorophyll a, chlorophyll b and total chlorophyll when cultivated in the presence of forage residues. At 100 DAT, the following photosynthetic variables were affected in pequi plants: A, Fv/Fm, ETR, NPQ, chlorophyll a, chlorophyll b and total chlorophyll, when cultivated in the presence of forage residues. Pequi plants had reduced relative dry matter yield when grown in the presence of U. decumbens. This variable was also affected when pequi was grown in increasing concentrations of residues of the species U. decumbens, M. minutiflora and P. notatum.

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