Photosynthesis in the Aquatic Macrophyte Egeria densa. III. Gas Exchange Studies

1979 ◽  
Vol 6 (4) ◽  
pp. 499 ◽  
Author(s):  
JA Browse ◽  
FI Dromgoole ◽  
JMA Brown
Keyword(s):  
Gas Exchange ◽  
Aquatic Macrophyte ◽  
Ambient Medium ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Open Circuit ◽  
Co2 Uptake ◽  
Total Resistance ◽  
Egeria Densa ◽  
Co2 Response

When free CO2 alone was present in the ambient medium, photosynthesis by Egeria densa Planch displayed an apparent Km of 77 μM. A light- and CO2-saturated rate of 100 μmol C (mg Chl)-1 h-1 was achieved only in 400 μM CO2(aq) [c. 1% CO2(g)]. The CO2 response data and other considerations suggest that, although the carboxylation and mesophyll resistances (3800 s m-1 and <9000 s m-1 respectively) are considerably higher than in aerial plant leaves, the boundary layer is the highest component (> 27 000 s m-1) of the total resistance. An increase in the total resistance of 7200 s m-1 between 0.02 and 0.21 atm O2 (2 and 21 kPa O2) is attributed to photorespiration. Closed and open circuit gas exchange experiments demonstrated that bicarbonate is taken up by the plant cells and does not act merely as a reservoir of inorganic carbon for production of CO2 at the plasmalemma. Bicarbonate stimulated photosynthesis, even when the free CO2 concentration was below the CO2 compensation point. The total resistance to bicarbonate uptake appears to be 8-12 times that for CO2 uptake presumably due to the processes of active uptake, transport and/or conversion to CO2 involved in bicarbonate but not CO2 assimilation.

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.

An Empirical Model of Net Photosynthesis and Leaf Conductance for the Simulation of Diurnal Courses of CO2 and H2O Exchange

1985 ◽  
Vol 12 (5) ◽  
pp. 513 ◽  
Author(s):  
M Kuppers ◽  
ED Schulze
Keyword(s):  
Gas Exchange ◽  
Empirical Model ◽  
Climatic Factors ◽  
Net Photosynthesis ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Uptake ◽  
Diurnal Courses ◽  
Humidity Response ◽  
Steady State Responses

An empirical model of CO2 uptake and water loss of leaves is established using steady-state responses of gas exchange to climatic factors as input. From the model the response surface of net CO2 assimilation and leaf conductance to climate can be derived. The model consists of two submodels, one describing the response of CO2 uptake to light and temperature, the other describing the response of leaf conductance to temperature and humidity. Both submodels are joined via the linear relationship between CO2 uptake and leaf conductance at short-term (minutes) variation of irradiance. From the humidity response of leaf conductance and the 'demand function' (Raschke 1979) of CO2 uptake in the mesophyll, the effect of stomata on the diffusion of CO2 between leaf and air is determined. The model is tested by comparing measured and calculated diurnal courses of gas exchange for two plants of Pinus silvestris, differing in photosynthetic capacity due to different levels of magnesium nutrition. Applications and limitations of the model are discussed.

scholarly journals Gas exchange, growth, and quality of passion fruit seedlings cultivated with saline water

2021 ◽  
Vol 42 (1) ◽  
pp. 137-154
Author(s):  
Geovani Soares de Lima ◽  
◽  
José Nathanael Ferreira de Andrade ◽  
Mizael Nabor Vaz de Medeiros ◽  
Lauriane Almeida dos Anjos Soares ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Saline Water ◽  
Block Design ◽  
Intercellular Co2 Concentration ◽  
Relative Yield ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Passion Fruit ◽  
Water Salinity

This study was conducted to evaluate the gas exchange, growth, and quality of passion fruit cultivars under irrigation with waters of different salinity levels. The experiment was conducted in a greenhouse, in Pombal-PB, Brazil, using a randomized block design in a 5 ? 2 factorial arrangement, with five levels of electrical conductivity of irrigation water (0.3, 1.1, 1.9, 2.7, and 3.5 dS m-1) and two passion fruit cultivars (BRS Sol do Cerrado and Guinezinho), with three plants per plot and four replicates. The reduction in transpiration, intercellular CO2 concentration and CO2 assimilation rate in passion fruit plants grown with saline water was related to factors of stomatal and non-stomatal origin. Gas exchange and growth of passion fruit cultivars were negatively affected by water salinity from 0.3 dS m-1 at 75 days after sowing. Despite the reduction in the growth of the passion fruit cultivars, irrigation with water of up to 3.5 dS m-1 could be used to obtain seedlings with acceptable quality. Based on the relative yield of total dry phytomass, the passion fruit cultivars BRS Sol do Cerrado and Guinezinho were classified as moderately sensitive to water salinity during the seedling phase.

scholarly journals Gas exchange, growth, and production of mini-watermelon under saline water irrigation and phosphate fertilization

2020 ◽  
Vol 41 (6supl2) ◽  
pp. 3039-3052
Author(s):  
Geovani Soares de Lima ◽  
◽  
Charles Macedo Félix ◽  
Saulo Soares da Silva ◽  
Lauriane Almeida dos Anjos Soares ◽  
...  
Keyword(s):  
Salt Stress ◽  
Gas Exchange ◽  
Saline Water ◽  
Block Design ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Northeastern Brazil ◽  
Randomized Block Design ◽  
Semi Arid Region

In the semi-arid region of Northeastern Brazil, due to the occurrence of excess salts, both in the water and soil, plants are constantly exposed to various conditions of abiotic stress. Thus, it is extremely important to identify methods capable of minimizing the effects of salt stress on plants as a way to ensure the expansion of irrigated areas. In this context, the objective of this study was to evaluate the gas exchange, growth, and production of mini-watermelon irrigated with saline waters and fertilized with phosphorus. The experiment was conducted in pots under greenhouse conditions in Pombal, PB, Brazil, using a randomized block design in a 5 x 4 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water—ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1), four phosphorus doses— PD (60, 80, 100, and 120% of the recommendation), and with three replicates. Watermelon plants cv. Sugar Baby were sensitive to water salinity greater than 0.3 dS m-1, with more pronounced inhibition of gas exchange, growth, and production. Reduction in the CO2 assimilation rate of watermelon plants cv. Sugar Baby was associated with factors of stomatal and non-stomatal origin. Phosphorous doses corresponding to 73 and 88% of the recommended values promoted an increase in the intercellular CO2 concentration and stem diameter of mini-watermelon plants. P2O5 doses ranging from 60 to 120% of the recommendation did not mitigate the effects of salt stress on the cultivation of watermelon cv. Sugar Baby.

The interplay between limiting processes in C3 photosynthesis studied by rapid-response gas exchange using transgenic tobacco impaired in photosynthesis

1998 ◽  
Vol 25 (8) ◽  
pp. 859 ◽  
Author(s):  
Sari Ruuska ◽  
T. John Andrews ◽  
Murray R. Badger ◽  
Graham S. Hudson ◽  
Agu Laisk ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Co2 Assimilation ◽  
Small Subunit ◽  
Rapid Response ◽  
Co2 Uptake ◽  
Wild Type ◽  
Gapdh Activity ◽  
Nicotiana Tabacum L ◽  
C3 Photosynthesis ◽  
Gas Exchange System

A gas-exchange system with a rapid response time was used to study the interplay between rate-limiting processes of C3 photosynthesis in wild-type tobacco (Nicotiana tabacum L. cv. W38) and transgenic tobaccos with antisense DNAs directed against the Rubisco small subunit (anti-SSu plants) or the chloroplast glyceraldehyde-3-phosphate dehydrogenase (anti-GAPDH plants). High ribulosebisphos-phate (RuBP) pools were generated in leaves by exposing them briefly to very low CO2, after which they were transferred to varying CO2 concentrations, and transient CO2 assimilation rates were measured within the first 2–3 s. Comparison of the transient (RuBP-saturated) and steady-state rates confirmed that the CO2 assimilation rate in anti-SSu plants was RuBP-saturated (i.e. Rubisco limited) at all intercellular CO2 partial pressures (Ci), and that, in anti-GAPDH plants, the transition from RuBP-saturation to RuBP-limitation occurred at lower assimilation rates and lower Ci as GAPDH activity was decreased. In addition, we investigated whether the integrated post-illumination CO2 uptake could be used as a non-destructive means of estimating RuBP pools in leaves. In wild-type plants there was generally a good agreement between RuBP pools extracted from leaves after rapid freeze-clamping and estimates made from post-illumination CO2 uptake. However, in the anti-SSu plants, the post- illumination CO2 uptake underestimated the actual RuBP content and the discrepancy became larger as the Rubisco content decreased. Possible explanations for this are discussed.

scholarly journals PHOTOSYNTHETIC EFFICIENCY OF TOMATO PLANTS SUBMITTED TO CALCIUM SILICATE APPLICATION

2020 ◽  
Vol 7 (4) ◽  
pp. 49-58
Author(s):  
Pablo Wenderson Ribeiro Coutinho ◽  
Márcia De Moraes Echer ◽  
Vandeir Francisco Guimarães ◽  
Maria Do Carmo Lana ◽  
Adriano Mitio Inagaki ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Use ◽  
Photosynthetic Pigments ◽  
Calcium Silicate ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Leaf Transpiration ◽  
Full Flowering ◽  
Internal Concentration ◽  
Internal Co2

The objective was to evaluate the effect of calcium silicate on the chlorophyll content and gas exchange of two tomato hybrids. The design used was in randomized blocks in a 2x5 factorial scheme, with four replications. The first factor was composed of two tomato hybrids: Ivety and Natália, and the second factor was composed of five doses of calcium silicate (0, 150, 300, 450, and 600 kg ha-1), applied to the substrate before planting the seedlings. Gas exchange: net CO2 assimilation rate (A), leaf transpiration rate (E), stomatal conductance (gs), internal CO2 concentration (Ci), water-use efficiency (WUE), intrinsic efficiency water use (iWUE), and instant carboxylation efficiency (ACi); SPAD index and the levels of chlorophylls a, b, and total were evaluated. The analyzes were performed in the stages of first flowering (17 days after transplanting - DAT), full flowering (58 DAT), and full fruiting (78 DAT). At 17 DAT, no difference was observed for gas exchange variables and photosynthetic pigments. The application of calcium silicate reduced gas exchange and photosynthetic pigments at 58 DAT. The hybrid Natália had the highest A, WUE, iWUE, and ACi at 78 DAT. However, the hybrid Ivety in the same growth stage, in full fruiting, was superior only for the internal concentration of CO2 and SPAD index, with no difference for photosynthetic pigments.

scholarly journals Gas exchange of the umbu tree under semi-arid conditions

2004 ◽  
Vol 26 (2) ◽  
pp. 206-208 ◽  
Author(s):  
José Moacir Pinheiro Lima Filho
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Rainy Season ◽  
Exchange Process ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Internal Co2 ◽  
Gas Exchange Process ◽  
Infrared Gas Analyzer ◽  
Dry And Rainy Seasons

A study was carried out at Embrapa Semi-Árido, Petrolina-PE, Brazil, aiming to understand the gas exchange process of the umbu tree (Spondias tuberosa Arr. Cam.) in the dry and rainy seasons. Stomatal conductance, transpiration, photosynthesis and internal CO2 concentration were obtained with a portable infrared gas analyzer (IRGA). During the dry season the umbu tree showed a much lower stomatal conductance early in the morning, as soon as the vapor pressure deficit increased, apparently affecting CO2 assimilation more than transpiration. The highest values were detected around 6:00 am but decreased to the lowest points between 10:00 am and 2:00 pm. During the rainy season, however, stomatal conductance, transpiration and photosynthesis were significantly higher, reaching the highest values between 8:00 and 10:00 am and the lowest around 2:00 pm. It was also observed at 4:00 pm, mainly during the rainy season, an increase on these variables indicating that the umbu tree exhibits a two-picked daily course of gas exchange.

Characteristics of CO2 exchange between peach stems and the atmosphere

2005 ◽  
Vol 32 (9) ◽  
pp. 787 ◽  
Author(s):  
Giorgio A. Alessio ◽  
Fabrizio Pietrini ◽  
Federico Brilli ◽  
Francesco Loreto
Keyword(s):  
Electron Transport ◽  
Gas Exchange ◽  
Time Course ◽  
Heat Dissipation ◽  
Prunus Persica ◽  
Co2 Concentration ◽  
Co2 Uptake ◽  
Atmospheric Conditions ◽  
Stem Photosynthesis ◽  
Natural Concentration

Gas exchange by stems is dominated by respiratory CO2 emission, but photosynthetic CO2 uptake might also occur in stem bark. We show that light-dependent CO2 uptake was present and often exceeded CO2 release by respiration in illuminated current-year peach (Prunus persica L.) stems. Respiration of peach stems, as detected by 12CO2 release into air in which the natural concentration of 12CO2 was replaced with 13CO2, was lower in the light than in the dark, but this accounted for only a fraction of the observed total CO2 uptake by illuminated stems. Stem photosynthesis was saturated at low light and was negatively affected by elevated assay temperatures (30°C), especially when combined with light intensities above saturation. An inefficient mechanism of heat dissipation by transpiration in stomata-free stems might help explain this effect. Photosynthesis was rapidly stimulated and the electron transport rate was reduced when photorespiration was suppressed by exposure to low (2 kPa) oxygen. The time-course of these changes was closely associated with a transient burst of CO2 uptake concurrent with a reduced inhibition of fluorescence yield. Photosynthesis was also stimulated by exposure to elevated (twice ambient) CO2 concentration. These combined measurements of gas exchange and fluorescence suggested that (a) photorespiration may also be active in the bark of peach stems, (b) O2 and CO2 concentrations in the bark of peach stems may be similar to ambient concentrations, (c) a large amount of electron transport unrelated to photosynthesis and photorespiration may also be present in peach stems, and (d) stem photosynthesis may be enhanced under future atmospheric conditions.

scholarly journals Physiological alterations and production of guava under water salinity and nitrogen fertilizer application

2018 ◽  
Vol 39 (5) ◽  
pp. 1945 ◽  
Author(s):  
Idelfonso Leandro Bezerra ◽  
Hans Raj Gheyi ◽  
Reginaldo Gomes Nobre ◽  
Joicy Lima Barbosa ◽  
Reynaldo Teodoro de Fátima ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Transpiration Rate ◽  
Saline Water ◽  
Co2 Concentration ◽  
Fertilizer Application ◽  
Co2 Assimilation ◽  
Fruit Weight ◽  
Water Salinity ◽  
Physiological Variables ◽  
Equatorial Diameter

Adequate management of saline water irrigation and nitrogen (N) fertilizer application in agriculture can contribute substantially to expanding guava cultivation in the semi-arid region of Northeast Brazil. This study aimed to evaluate gas exchange and production of ‘Paluma’ guava cultivated with different levels of water salinity and N. The experiment was carried out in drainage lysimeters under field conditions in an experimental area of the Federal University of Campina Grande (UFCG), Campus of Pombal, PB, Brazil. The experimental design was randomized blocks, in a 5 × 4 factorial scheme, with five levels of water salinity – ECw (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four doses of N (70, 100, 130 and 160% of the recommendation) with three replicates. The dose relative to 100% corresponded to 541.1 mg of N dm-3 of soil. The following production components were evaluated: number of fruits, mean fruit weight, polar and equatorial diameter of fruits, and polar diameter/equatorial diameter ratio. In addition, the following physiological variables were evaluated at 180 days after fruit pruning: stomatal conductance, CO2 assimilation rate, internal CO2 concentration and transpiration rate. CO2 assimilation and transpiration rate were used to calculate instantaneous water use efficiency. The interaction between water salinity and N doses did not cause significant effects on any variable studied. Irrigation water salinity above 0.3 dS m-1 hampered gas exchange at 180 days after fruit pruning and negatively affected production components.

scholarly journals Salinity Stress Affects Photosynthesis, Malondialdehyde Formation, and Proline Content in Portulaca oleracea L.

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 845
Author(s):  
Helena Hnilickova ◽  
Kamil Kraus ◽  
Pavla Vachova ◽  
Frantisek Hnilicka
Keyword(s):  
Salt Stress ◽  
Water Potential ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Proline Content ◽  
Portulaca Oleracea ◽  
Control Group ◽  
Malondialdehyde Formation ◽  
Salinity Levels ◽  
Mda Content

In this investigation, the effect of salt stress on Portulaca oleracea L. was monitored at salinity levels of 100 and 300 mM NaCl. At a concentration of 100 mM NaCl there was a decrease in stomatal conductance (gs) simultaneously with an increase in CO2 assimilation (A) at the beginning of salt exposure (day 3). However, the leaf water potential (ψw), the substomatal concentration of CO2 (Ci), the maximum quantum yield of photosystem II (Fv/Fm), and the proline and malondialdehyde (MDA) content remained unchanged. Exposure to 300 mM NaCl caused a decrease in gs from day 3 and a decrease in water potential, CO2 assimilation, and Fv/Fm from day 9. There was a large increase in proline content and a significantly higher MDA concentration on days 6 and 9 of salt stress compared to the control group. After 22 days of exposure to 300 mM NaCl, there was a transition from the C4 cycle to crassulacean acid metabolism (CAM), manifested by a rapid increase in substomatal CO2 concentration and negative CO2 assimilation values. These results document the tolerance of P. oleracea to a lower level of salt stress and the possibility of its use in saline localities.

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