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 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.

Stomatal Limitation of Photosynthesis in Abscisic Acid-Treated and in Water-Stressed Leaves Measured at Elevated CO2

1988 ◽  
Vol 15 (4) ◽  
pp. 495 ◽  
Author(s):  
SP Robinson ◽  
WJR Grant ◽  
BR Loveys
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Quantum Yield ◽  
Oxygen Evolution ◽  
Stomatal Closure ◽  
Co2 Concentration ◽  
Assimilation Rate ◽  
High Co2 ◽  
Co2 Concentrations ◽  
Ambient Co2

Feeding 10-5M (�)-abscisic acid (ABA) via the petioles of detached leaves of apricot (Prunus armeniaca) or sunflower (Helianthus annuus) decreased stomatal conductance and assimilation rate but not the calculated intercellular CO2 concentration (Ci) suggesting non-stomatal as well as stomatal inhibition of photosynthesis. Evidence for non-stomatal inhibition was not observed in spinach (Spinacia oleracea). There was no significant decrease in rates of electron transport nor ribulosebisphosphate carboxylase (Rubisco) activity in intact chloroplasts isolated from ABA-treated sunflower leaves. Oxygen evolution by leaf discs with 3% CO2 in the gas phase was inhibited in ABA- treated sunflower and apricot leaves but not in spinach; the inhibition was only half as great as the inhibition of assimilation rate at ambient CO2. The quantum yield of oxygen evolution decreased in ABA-treated sunflower leaves in proportion to the decrease in the light-saturated rate. There was no significant difference in room temperature chlorophyll fluorescence of ABA-treated leaves compared to controls. Stomatal conductance of sunflower leaves decreased by more than 90% when the CO2 concentration was increased from 340 ppm to 1000 ppm but at much higher CO2 concentrations the stomata appeared to reopen. Stomatal conductance at 2-3% CO2 (20 000-30 000 ppm) was 50% that at ambient CO2. This reopening of stomata at high CO2 was inhibited in previously water-stressed or ABA-treated plants. In unstressed leaves, the maximum rate of oxygen evolution occurred at 0.5-2% CO2 but in ABA-treated leaves 10-15% CO2 was required for maximum rates. It is suggested that stomatal closure may limit photosynthesis in ABA-treated or previously water-stressed leaves even at the relatively high CO2 concentrations normally used in the leaf disc oxygen electrode. The inhibition of photosynthesis by ABA is largely overcome at saturating CO2. The apparent non-stomatal inhibition suggested by gas exchange measurements and the decreased quantum yield could be explained by patchy stomatal closure in response to ABA.

Crassulacean Acid Metabolism and Diurnal Variations of Internal CO2 and O2 Concentrations in Sedum praealtum DC

1979 ◽  
Vol 6 (4) ◽  
pp. 557 ◽  
Author(s):  
MH Spalding ◽  
DK Stumpf ◽  
MSB Ku ◽  
RH Burris ◽  
GE Edwards
Keyword(s):  
Malic Acid ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Dark Period ◽  
Stomatal Closure ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
C3 Plants ◽  
Cam Plants ◽  
Internal Co2

Internal CO2 and O2 concentrations in Sedum praealtum DC. were determined by gas chromatography of 200-�l gas samples. Day-night monitoring showed that internal CO2 varied from a high of approximately 4000 �l/l during periods of daytime stomatal closure to a low of 270-280 �l/l during the dark period (stomata open). Internal O2 concentrations varied from a high of approximately 26 % at midday to a low of 20.8 % during the dark period. The calculated internal O2/CO2 ratio varied about 12-15-fold from 50-60 near midday to approximately 750 during the dark period (ratio in normal air is roughly 600). Day-night patterns of CO2 exchange and malic acid concentration were typical for a plant with crassulacean acid metabolism (CAM). Influx of CO2 during the late light period was inhibited by O2, but dark CO2 influx was O2-insensitive. Gas samples taken near midday from several CAM plants all showed elevated internal CO2 and O2 concentrations. Ratios of O2/CO2 in these plants ranged from 81 in Sedum praealtum to 285 in Hoya carnosa. The highest internal O2 concentration observed was 41.5% in Kalanchoe gastonis-bonnieri. The high CO2 concentration in leaves of CAM plants during daytime stomatal closure should provide a near- saturating level of this substrate for photosynthesis. In comparison to C3 plants, the relatively low O2/CO2 ratio in the CAM leaf during malic acid decarboxylation should be favourable for photosynthesis and unfavourable for O2 inhibition of photosynthesis.

scholarly journals Quinoa for the Brazilian Cerrado: Agronomic Characteristics of Elite Genotypes under Different Water Regimes

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1591
Author(s):  
Patrícia Carvalho da Silva ◽  
Walter Quadros Ribeiro Junior ◽  
Maria Lucrecia Gerosa Ramos ◽  
Sonia Maria Costa Celestino ◽  
Alberto do Nascimento Silva ◽  
...  
Keyword(s):  
Grain Quality ◽  
Winter Season ◽  
Field Conditions ◽  
Water Restriction ◽  
Water Regimes ◽  
Agronomic Characteristics ◽  
Relative Water ◽  
Different Seasons ◽  
The Relationship

Quinoa stands out as an excellent crop in the Cerrado region for cultivation in the off-season or irrigated winter season. Here, we tested the effects of different water regimes on the agronomic characteristics, physiology, and grain quality of different elite quinoa genotypes under field conditions. The experiment was conducted under field conditions at Embrapa Cerrados (Planaltina, DF, Brazil). The experimental design was in randomized blocks, in a split-plot scheme, with four replications. The plots were composed of 18 quinoa genotypes and modified BRS Piabiru (the currently used genotype), and the split-plots were divided into 4 different water regimes. The following variables were evaluated: productivity and productivity per unit of applied water (PUAA), plant height, flavonoids, anthocyanins, gas exchange, chlorophyll, leaf proline, and relative water content. Our results showed that water regimes between 309 and 389 mm can be recommended for quinoa in the Cerrado region. CPAC6 and CPAC13 presented the highest yield and PUAA under high and intermediate WRs, and hence were the most suitable for winter growth under irrigation. CPAC17 is most suitable for off-season growth under rainfed conditions, as it presented the highest PUAA under the low WRs (247 and 150). CPAC9 stood out in terms of accumulation of flavonoids and anthocyanins in all WRs. Physiological analyses revealed different responses of the genotypes to water restriction, together with symptoms of stress under lower water regimes. Our study reinforces the importance of detailed analyses of the relationship between productivity, physiology, and water use when choosing genotypes for planting and harvest in different seasons.

scholarly journals Effects of Elevated CO2 and Heat on Wheat Grain Quality

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1027
Author(s):  
Xizi Wang ◽  
Fulai Liu
Keyword(s):  
Grain Quality ◽  
State Of The Art ◽  
Co2 Concentration ◽  
Yield Potential ◽  
Wheat Crop ◽  
Wheat Grain ◽  
Wheat Growth ◽  
Elevated Atmospheric Co2 ◽  
Huge Impact ◽  
Increasing Demand

Wheat is one of the most important staple foods in temperate regions and is in increasing demand in urbanizing and industrializing countries such as China. Enhancing yield potential to meet the population explosion around the world and maintaining grain quality in wheat plants under climate change are crucial for food security and human nutrition. Global warming resulting from greenhouse effect has led to more frequent occurrence of extreme climatic events. Elevated atmospheric CO2 concentration (eCO2) along with rising temperature has a huge impact on ecosystems, agriculture and human health. There are numerous studies investigating the eCO2 and heatwaves effects on wheat growth and productivity, and the mechanisms behind. This review outlines the state-of-the-art knowledge regarding the effects of eCO2 and heat stress, individually and combined, on grain yield and grain quality in wheat crop. Strategies to enhance the resilience of wheat to future warmer and CO2-enriched environment are discussed.

scholarly journals True and Pseudo Cholinesterase levels in short and long-term of pesticides exposures

2020 ◽  
pp. 9-12
Author(s):  
Mohammed Abdul Rahman ◽  
Raghunatha Rao D ◽  
Vasantha L
Keyword(s):  
Whole Blood ◽  
Acute Poisoning ◽  
Mean Value ◽  
Serum Cholinesterase ◽  
Control Group ◽  
Study Group ◽  
Chronic Poisoning ◽  
The Mean ◽  
The Difference ◽  
And Control

The present study is aimed to study and analyze the true and pseudo Cholinesterase levels in the subjects exposed to pesticides during short term by intentional or accidental intake and long term exposure due to their occupation were studied at Department of Biochemistry, SVS medical college and hospital mahbubnagar district. Whole blood cholinesterase levels and Pseudo cholinesterase levels were estimated. 150 people were taken as controls who had no medical illness and a total number of 300 cases of pesticide poisoning were selected, aged between 20 to 55 years, which consist of 150 acute poisoning and 150 chronic poisoning subjects in Mahbubnagar district, were taken as case study, the detailed case history and the type of organophosphorus pesticide taken were recorded. Mean and standard deviation (S.D) of all variables were calculated and compared with those of controls. Statistical significance was assessed and P-value <0.05 were considered significant.           During acute poisoning the mean value of Whole blood cholinesterase/True cholinesterase (U / L) in acute poisoning cases on first day was 1.267± 0.612 on 3th day was 1.651±0.647, on 7th day was 2.221±0.684 and at the end of 6 months was 3.970±0.404.The difference between the study group and control group (4.0 ± 0.39) was found to be statistically significant in1st, 3rd, 7th day but not significant at the end of 6 months. The mean value of serum cholinesterase/pseudo cholinesterase (U/L) in acute poisoning cases on first day was 2213.05 ± 1749.81, on 3th day was 2862.3 ± 2025.6, on 7th day was 4008.4 ± 2355.9 and at the end of 6 months was 7708.34 ± 880.72.The difference between the study group and control group (7991.97 ± 1276.5) was found to be statistically significant in1st, 3rd, 7th day but not significant at the end of 6 months. During chronic poisoning (exposure) the mean value of Whole blood cholinesterase (U/L) in controls is 4.0 ± 0.39 as compared to 3.019 ± 0.848 in cases of chronic poisoning. The difference between the study group and control group was found to be statistically significant. The mean value of serum cholinesterase/pseudo cholinesterase (U/L) in controls was 7991.97 ± 1276.5 as compared to 6214 ± 1189 in cases of chronic poisoning. The difference between the study group and control group was found to be statistically significant.

scholarly journals A return to large-scale features of Pliocene climate: the Pliocene Model Intercomparison Project Phase 2

2020 ◽  
Author(s):  
Alan M. Haywood ◽  
Julia C. Tindall ◽  
Harry J. Dowsett ◽  
Aisling M. Dolan ◽  
Kevin M. Foley ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Temperature Response ◽  
Surface Air Temperature ◽  
Co2 Concentration ◽  
Mean Value ◽  
System Response ◽  
Phase 2 ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. The Pliocene epoch has great potential to improve our understanding of the long-term climatic and environmental consequences of an atmospheric CO2 concentration near ~ 400 parts per million by volume. Here we present the large-scale features of Pliocene climate as simulated by a new ensemble of climate models of varying complexity and spatial resolution and based on new reconstructions of boundary conditions (the Pliocene Model Intercomparison Project Phase 2; PlioMIP2). As a global annual average, modelled surface air temperatures increase by between 1.4 and 4.7 °C relative to pre-industrial with a multi-model mean value of 2.8 °C. Annual mean total precipitation rates increase by 6 % (range: 2 %–13 %). On average, surface air temperature (SAT) increases are 1.3 °C greater over the land than over the oceans, and there is a clear pattern of polar amplification with warming polewards of 60° N and 60° S exceeding the global mean warming by a factor of 2.4. In the Atlantic and Pacific Oceans, meridional temperature gradients are reduced, while tropical zonal gradients remain largely unchanged. Although there are some modelling constraints, there is a statistically significant relationship between a model's climate response associated with a doubling in CO2 (Equilibrium Climate Sensitivity; ECS) and its simulated Pliocene surface temperature response. The mean ensemble earth system response to doubling of CO2 (including ice sheet feedbacks) is approximately 50 % greater than ECS, consistent with results from the PlioMIP1 ensemble. Proxy-derived estimates of Pliocene sea-surface temperatures are used to assess model estimates of ECS and indicate a range in ECS from 2.5 to 4.3 °C. This result is in general accord with the range in ECS presented by previous IPCC Assessment Reports.

Assimilate Source-Sink Relationships in Capsicum annuum L. III. The Effects of Fruit Excision on Photosynthesis and Leaf and Stem Carbohydrates.

1978 ◽  
Vol 5 (1) ◽  
pp. 1 ◽  
Author(s):  
AJ Hall ◽  
FL Milthorpe
Keyword(s):  
Control Mechanism ◽  
Dark Respiration ◽  
Soluble Sugars ◽  
Co2 Concentration ◽  
Co2 Uptake ◽  
Factors Affecting ◽  
Co2 Compensation Point ◽  
Time Period ◽  
Internal Co2 ◽  
Source Sink

Removal of the rapidly growing fruit from a Capsicum plant reduced the rate of net CO2 uptake by its leaves by up to 30% during the time period explored (0.5 - 7 days). This reduction was associated with increases in both the leaf (to about 200%) and intracellular (to about 30%) resistances, these changes having about equal effects on reducing the rate of CO2 uptake. Changes in photorespiration, dark respiration and CO2 compensation point were very small. The rate of CO2 uptake and the associated resistances were also changed by modifying the light regime and other factors affecting the source-sink balance. Changes in the leaf resistance were not attributable to variations in the internal CO2 concentration or in the water economy of the leaf; its control mechanism remains unexplained. The concentration of soluble sugars in the source leaf was completely unaffected but that of polysaccharides was changed by defruiting and by 50% defoliation. However, variations in the intracellular resistance were not closely related to these changes and there is yet no evidence of the nature of its control mechanism. Changes in both soluble sugars and polysaccharides in the stem were more pronounced than in the leaves.

Local adaptation of a Lessepsian invader species to winter conditions in the Mediterranean Sea

2021 ◽  
Author(s):  
Débora Silva Raposo ◽  
Raphaël Morard ◽  
Christiane Schmidt ◽  
Michal Kucera
Keyword(s):  
Quantum Yield ◽  
Mediterranean Sea ◽  
Red Sea ◽  
Photosynthetic Activity ◽  
Eastern Mediterranean ◽  
Effective Quantum Yield ◽  
Mediterranean Populations ◽  
Cold Temperatures ◽  
Invasion Front ◽  
The Mediterranean

&lt;p&gt;In recent decades the &amp;#8220;Lessepsian&amp;#8221; migration caused a rapid change in the marine community composition due to the invasion of alien species from the Red Sea into the Mediterranean Sea. Among these invaders is the large benthic foraminifera &lt;em&gt;Amphistegina lobifera&lt;/em&gt;, a diatom-bearing species that recently reached the invasion front in Sicily. There it copes with colder winters and broader temperature than in its original source, the Red Sea. It is not yet known how (or if) the population from the invasion front has developed adaptation to this new thermal regime. Understanding the modern marine invasive patterns is a crucial tool to predict future invasive successes in marine environments. Therefore, in this study we aim to evaluate the physiological responses to cold temperatures of &lt;em&gt;A. lobifera&lt;/em&gt; populations at three different invasive stages: source (Red Sea), early invader (Eastern Mediterranean) and invasion front (Sicily). For this, we conducted a culturing experiment in which we monitored the responses of the foraminifera (growth, motility) to temperatures of 10, 13, 16, 19&amp;#176;C + control (25&amp;#176;C) over four weeks. To address what is the role of their endosymbionts in the adaptation process, we also monitored their photosynthetic activity (Pulse Amplitude Modulation - PAM fluorometer) during the experiment. The growth rate of the foraminifera was reduced for all populations below 19&amp;#176;C as well as the motility, reduced until 16&amp;#176;C and dropping to zero below 13&amp;#176;C. The response of the endosymbionts was however different. There was a reduced photosynthetic activity of the Red Sea and Eastern Mediterranean populations at colder temperatures observed by the lower maximum quantum yield (Fv:Fm) and effective quantum yield (Y(II)), when compared to their initial levels and to the other treatments. In the meantime, the endosymbionts of the Sicily population stood out with the highest photosynthetic activity (Fv:Fm and Y(II)) in the treatments bellow 13 &amp;#176;C (P &lt; 0.05). In conclusion, we observed that while the host responses were similar between the three populations, the endosymbionts from the invasion front population shows the best performance at colder temperatures. This suggests that the photo-symbiosis has an important role in adaptation, most likely being a key factor to the success of past and future migrations.&lt;/p&gt;

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