The relative limitation of photosynthesis by mesophyll conductance in co-occurring species in a temperate rainforest dominated by the conifer Dacrydium cupressinum

2003 ◽  
Vol 30 (12) ◽  
pp. 1197 ◽  
Author(s):  
Evan H. De Lucia ◽  
David Whitehead ◽  
Michael J. Clearwater
Keyword(s):  
Phaseolus Vulgaris ◽  
Partial Pressure ◽  
Tree Species ◽  
Radiata Pine ◽  
Leaf Nitrogen ◽  
Herbaceous Plant ◽  
Mesophyll Conductance ◽  
Co2 Partial Pressure ◽  
Fluorescence Measurements ◽  
Partial Pressure Of Co2

The capacity to conduct CO2 from the intercellar spaces in leaves to the site of fixation (mesophyll conductance, gm) may pose a significant limitation to photosynthesis. Dacrydium cupressinum Sol. ex Lamb. (rimu), a native conifer of New Zealand, and other members of the Podocarpaceae evolved during the Jurassic when the partial pressure of CO2 exceeded 200 Pa. This species has low rates of photosynthesis and high levels of leaf nitrogen, which have led to the hypothesis that low gm restricts photosynthesis. Mesophyll conductance was estimated from gas-exchange and fluorescence measurements for this and other co-occurring tree species [Prumnopitys ferruginea D.�Don (miro), Weinmannia racemosa L.f. (kāmahi), Meterosideros umbellata Cav. (rata)]. Pinus radiata D. Don (radiata pine) and Phaseolus vulgaris L. (bean) were included to provide comparisons with a rapidly growing tree and herbaceous plant with relatively high photosynthetic rates. Mesophyll conductance was not statistically different among indigenous tree species but was lowest for D. cupressinum. This species also had the lowest ratio of mesophyll to stomatal conductance, gm / gst and was the only species where the decline in partial pressure of CO2 was greater from the intercellular air space to the site of fixation (16.3 Pa) than between the bulk air and the intercellular spaces (8.8 Pa), providing support for the hypotheses that low gm limits photosynthesis in this species. As a group, conifers had marginally lower gm and gm / gst ratio than angiosperms, but this difference was strongly influenced by the high values for Phaseolus vulgaris. That co-occurring members of the Podocarpaceae operated differently suggests that low gm may reflect a response to evolutionary pressures other than high atmospheric CO2 partial pressure.

Corrigendum to: The relative limitation of photosynthesis by mesophyll conductance in co-occurring species in a temperate rainforest dominated by the conifer Dacrydium cupressinum

2004 ◽  
Vol 31 (7) ◽  
pp. 759
Author(s):  
Evan H. De Lucia ◽  
Michael J. Clearwater ◽  
David Whitehead
Keyword(s):  
Phaseolus Vulgaris ◽  
Partial Pressure ◽  
Tree Species ◽  
Radiata Pine ◽  
Leaf Nitrogen ◽  
Herbaceous Plant ◽  
Mesophyll Conductance ◽  
Co2 Partial Pressure ◽  
Fluorescence Measurements ◽  
Partial Pressure Of Co2

The capacity to conduct CO2 from the intercellar spaces in leaves to the site of fixation (mesophyll conductance, gm) may pose a significant limitation to photosynthesis. Dacrydium cupressinum Sol. ex Lamb. (rimu), a native conifer of New Zealand, and other members of the Podocarpaceae evolved during the Jurassic when the partial pressure of CO2 exceeded 200 Pa. This species has low rates of photosynthesis and high levels of leaf nitrogen, which have led to the hypothesis that low gm restricts photosynthesis. Mesophyll conductance was estimated from gas-exchange and fluorescence measurements for this and other co-occurring tree species [Prumnopitys ferruginea D.�Don (miro), Weinmannia racemosa L.f. (kāmahi), Meterosideros umbellata Cav. (rata)]. Pinus radiata D. Don (radiata pine) and Phaseolus vulgaris L. (bean) were included to provide comparisons with a rapidly growing tree and herbaceous plant with relatively high photosynthetic rates. Mesophyll conductance was not statistically different among indigenous tree species but was lowest for D. cupressinum. This species also had the lowest ratio of mesophyll to stomatal conductance, gm / gst and was the only species where the decline in partial pressure of CO2 was greater from the intercellular air space to the site of fixation (16.3 Pa) than between the bulk air and the intercellular spaces (8.8 Pa), providing support for the hypotheses that low gm limits photosynthesis in this species. As a group, conifers had marginally lower gm and gm / gst ratio than angiosperms, but this difference was strongly influenced by the high values for Phaseolus vulgaris. That co-occurring members of the Podocarpaceae operated differently suggests that low gm may reflect a response to evolutionary pressures other than high atmospheric CO2 partial pressure.

Inhibition of CO2 Assimilation by Supraoptimal CO2: Effect of Light and Temperature

1983 ◽  
Vol 10 (1) ◽  
pp. 75 ◽  
Author(s):  
KC Woo ◽  
SC Wong
Keyword(s):  
Partial Pressure ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Co2 Partial Pressure ◽  
Low Co2 ◽  
O2 Partial Pressure ◽  
Partial Pressures ◽  
High Partial Pressure ◽  
Partial Pressure Of Co2

In cotton the rate of CO2 assimilation, at O2 partial pressures up to 200 mbar, increased to a maximum and then declined as the intercellular partial pressure of CO2 was increased. The specific intercellular partial pressure of CO2 at which rate of assimilation began to decline depended on the environmental conditions. At 19 mbar partial pressure of O2 the decline occurred at CO2 partial pressure >390 �bar. At 200 mbar partial pressure of O2 it occurred at CO2 partial pressure > 534 �bar. O2 increased the CO2 partial pressure required for inhibition but it did not appear to affect the steepness of the decline of rate of assimilation with further increase in partial pressure of CO2 once the decline became apparent. The decline was more readily observed at low temperature and low O2 partial pressure, and in plants grown at low light and NO3- levels. It was also observed in cowpea and sunflower. Changes in quantum efficiency in cotton at high and low CO2 concentrations were observed. At ambient CO2 concentration (300 �bar), the quantum yields measured at 19 and 200 mbar partial pressure of O2 were 0.072 � 0.0003 and 0.053 � 0.0060 mol CO2 per mol absorbed quanta, respectively. In contrast, at 900 �bar CO2 partial pressure the respective values were 0.050 � 0.0023 and 0.070 � 0.0006 mol CO2 per mol absorbed quanta. The nature of the inhibition of CO2 assimilation by high partial pressure of CO2 is discussed.

Photosynthetic Activity of Leaves of Pinus radiata and Nothofagus fusca After 1 Year of Growth at Elevated CO2

1996 ◽  
Vol 23 (5) ◽  
pp. 623 ◽  
Author(s):  
KP Hogan ◽  
D Whitehead ◽  
J Kallarackal ◽  
JG Buwalda ◽  
J Meekings ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Pinus Radiata ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Radiata Pine ◽  
Rubisco Activity ◽  
Co2 Partial Pressure ◽  
Partial Pressures ◽  
The Difference ◽  
Triose Phosphate Utilisation

Radiata pine (Pinus radiata D.Don) and red beech (Nothofagus fusca (Hook. f.) Oerst.) were grown for over 1 year at elevated (ELEV, 64 Pa) and ambient (AMB, 38 Pa) CO2 partial pressure in open-top chambers. Springtime measurements of overwintering leaves showed that light- and CO2-saturated photosynthetic rates (Amax) of pine leaves were similar for the two treatments (AMB: 6.7 � 1.08 μmol m-2 s-1, mean � 1 s.e.; ELEV: 6.6 � 0.47) but, for beech leaves, Amax was greater for AMB plants (8.8 � 0.90 μmol m-2 s-1) than for ELEV plants (6.10 � 0.71). Summertime measurements of leaves grown that spring showed that for pine, Amax was similar in the two CO2 treatments (AMB 14.9 μmol m-2 s-1 � 0.80; ELEV: 13.5 � 1.9) while, for beech, Amax was higher in AMB plants (21.0 � 1.1) than in ELEV plants (17.2 � 1.9), although the difference was not statistically significant. These results indicate downregulation of photosynthetic capacity of beech but not pine. Vcmax did not differ between treatments within species, suggesting that there was no acclimation of rubisco activity. Triose phosphate utilisation limitation may have contributed to the downregulation of Amax in beech. For pine, photosynthesis at treatment CO2 partial pressures was greater in ELEV plants in both spring and summer. For beech measured at treatment CO2 partial pressures, photosynthesis was greater in ELEV plants in summer, but was similar between treatments in the springtime.

scholarly journals Pengaruh Terapi Oksigen Menggunakan Non-Rebreathing Mask Terhadap Tekanan Parsial CO2 Darah pada Pasien Cedera Kepala Sedang

2014 ◽  
Vol 3 (1) ◽  
Author(s):  
Hendrizal Hendrizal ◽  
Syaiful Saanin ◽  
Hafni Bachtiar
Keyword(s):  
Clinical Trial ◽  
Partial Pressure ◽  
Oxygen Therapy ◽  
Head Injuries ◽  
Total Sample ◽  
Gas Mixture ◽  
Co2 Partial Pressure ◽  
Partial Pressure Of Co2 ◽  
Before And After ◽  
Intra Cranial Pressure

AbstrakTekanan parsial CO2sangat berpengaruh terhadap aliran darah otak (ADO) dan tekanan intra kanial. Latarbelakang penelitian ini adalah bahwa dalam teori tekanan gas campuran John Dalton dinyatakan bahwa jika salah satu tekanan gas dalam campuran gas bertambah maka tekanan parsial gas lain akan menurun. Penelitian ini bertujuan untuk mengetahui apakah peningkatan konsentrasi oksigen dalam Non-Rebreathing Mask (NRM) akan menurunkan tekanan parsial CO2, sehingga dapat digunakan untuk menurunkan PaCO2 sambil memperthankan PaO2 yang tinggi untuk menurunkan TIK (Tekanan Intra Kranial) pada pasien cedera kepala. Metode: Penelitian ini merupakan penelitian Clinical Trial dengan rancangan penelitian one shoot pretest and postest pada pasien cedera kepala sedang dengan GCS 9-13 yang dilakukan terapi konservatif di RS Dr. M. Djamil Padang. Pada pasien dinilai tekanan parsial CO2 darah sebelum dan setelah 6 jam terapi oksigen menggunakan NRM. Jumlah sampel sebanyak 16 pasien yang memenuhi kriteria inklusi. Hasil: Dari hasil penelitian didapatkan perbedaan bermakna tekanan parsial CO2 darah sebelum dan setelah terapi oksigen menggunakan NRM (p<0,05). Terjadi penurunan tekanan parsial CO2 darah setelah terapi oksigen mengunakan NRM dari39,00 ± 3,7 menjadi 432,06 ± 6,35. Pembahasan: Terapi oksigen menggunakan NRM dapat menurunkan tekanan parsial CO2 darah sehingga dapat digunakan untuk menurunkan tekanan intrakranial pada pasien cedera kepala sedang.Kata kunci: Terapi Oksigen, Non-Rebreathing Mask, Tekanan Parsial CO2 DarahAbstractThe partial pressure of CO2 is very influential on cerebral blood flow (CBF) and intra kanial pressure. The background of this research is that the pressure of the gas mixture in the theory of John Dalton stated that if one of the gas pressure in the gas mixture increases, the partial pressure of other gases will decline. This study aimed to determine whether the increase in oxygen concentration in the non-rebreathing mask (NRM) will decrease the partial pressure of CO2, so that it can be used to decrease PaCO2 while PaO2 still higher to protect brain from higher of ICT (intra-cranial pressure) state in patients with head injuries. Method: This research is a Clinical Trial with one shoot pretest and posttest design in patients with moderate head injury with GCS 9-13 conducted conservative treatment at the hospital Dr. M. Djamil Padang. In patients assessed blood CO2 partial pressure before and after 6 hours of oxygen therapy using the NRM. Total sample of 16 patients who met the incluton criteria. Result: The result showed significant differences in blood CO2 partial pressure before and after oxygen therapy using the NRM (P <0.05). There was a decrease of bloodCO2partial pressureafter oxygen therapy using NRM from 32.06 ± 6.35 to 39.00 ± 3.74. Discussion: Oxygen therapy using NRM can decrease blood CO2 partial pressure that can be used to reduce the intra-cranial pressure in patients with moderate head injury.Keywords: Oxygen Therapy, Non-Rebreathing Mask, Blood CO2 Partial Pressure

Seasonal variation of surface water CO2 partial pressure in the Southland Current, east of New Zealand

1999 ◽  
Vol 50 (5) ◽  
pp. 375 ◽  
Author(s):  
Kim I. Currie ◽  
Keith A. Hunter
Keyword(s):  
Biological Activity ◽  
New Zealand ◽  
Surface Water ◽  
Partial Pressure ◽  
Surface Waters ◽  
Sea Surface ◽  
Mixing Processes ◽  
Co2 Partial Pressure ◽  
Partial Pressure Of Co2 ◽  
Effects Of Temperature

The partial pressure of CO2 in the surface waters (pCO2sw) of the Southland Front east of New Zealand was determined over one annual cycle in 1992/93. Associated parameters of temperature, salinity and nutrients were also measured. Both the modified subtropical waters of the Southland Current and the cooler subantarctic surface waters were undersaturated with CO2 with respect to the atmosphere. The maximum ΔpCO2 of –150 µatm was measured in April 1993. A simple model taking into account the effects of temperature, biological activity and air–sea exchange applied to subantarctic surface water indicated that at different times of the year changes in sea surface temperature, biological activity and mixing processes are the dominant controls of pCO2sw .

scholarly journals A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

2021 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Paz Nativ ◽  
Yonatan Gräber ◽  
Yaron Aviezer ◽  
Ori Lahav
Keyword(s):  
Partial Pressure ◽  
Volatile Fatty Acids ◽  
Inorganic Carbon ◽  
Strong Acid ◽  
Direct Analysis ◽  
Anaerobic Digesters ◽  
Acid Titration ◽  
Partial Pressure Of Co2 ◽  
Ph Range

A new analytic approach is presented for determining the total volatile fatty acids (VFAT) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (CT) in the analyzed solution, along with two strong-acid titration points. The CT concentration can be determined by either a direct analysis (e.g., by using a TOC device) or by estimating it from the recorded partial pressure of CO2(g) in the biogas (often a routine analysis in anaerobic digesters). The titration is carried out to pH 5.25 and then to pH 4.25. The two titration results are plugged into an alkalinity-mass-based equation and then the two terms are subtracted from each other to yield an equation in which VFAT is the sole unknown (since CT is known and the effect of the total orthophosphate and ammonia concentrations is shown to be small at this pH range). The development of the algorithm and its verification on four anaerobic reactor liquors is presented, on both the raw water and on acetic acid-spiked samples. The results show the method to be both accurate (up to 2.5% of the expected value for VFAT/Alkalinity >0.2) and repetitive when the total orthophosphate and ammonia concentrations are known, and fairly accurate (±5% for VFAT >5 mM) when these are completely neglected. PHREEQC-assisted computation of CT from the knowledge of the partial pressure of CO2(g) in the biogas (and pH, EC and temperature in the liquor) resulted in a very good estimation of the CT value (±3%), indicating that this technique is adequate for the purpose of determining VFAT for alarming operators in case of process deterioration and imminent failure.

Separation of carotid body chemoreceptor responses to O2 and CO2 by oligomycin and by antimycin A

1982 ◽  
Vol 242 (3) ◽  
pp. C200-C206 ◽  
Author(s):  
E. Mulligan ◽  
S. Lahiri
Keyword(s):  
Steady State ◽  
Carbonic Anhydrase ◽  
Partial Pressure ◽  
Carotid Body ◽  
Body Tissue ◽  
Antimycin A ◽  
Tissue Ph ◽  
Co2 Partial Pressure ◽  
O2 Partial Pressure ◽  
Metabolic Hypothesis

The cat carotid chemoreceptor O2 and CO2 responses can be separated by oligomycin and by antimycin A. Both of these agents greatly diminish or abolish the chemoreceptor O2 response but not the nicotine or CO2 responses. After either oligomycin or antimycin, the responses to increases and decreases in arterial CO2 partial pressure (PaCO2) consisted of increases and decreases in activity characterized respectively by exaggerated overshoots and undershoots. These were eliminated by the carbonic anhydrase inhibitor, acetazolamide, suggesting that they resulted from changes in carotid body tissue pH. The steady-state PaCO2 response remaining after oligomycin was no longer dependent on arterial O2 partial pressure (PaO2). All effects of antimycin were readily reversible in about 20 min. The separation of the responses to O2 and CO2 indicates that there may be at least partially separate pathways of chemoreception for these two stimuli. The similarity of the oligomycin and antimycin results supports the metabolic hypothesis of chemoreception.

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