Effect of transjugular intrahepatic portosystemic shunt on pulmonary gas exchange in patients with portal hypertension and hepatopulmonary syndrome

AIM: To assess the impact of transjugular intrahepatic portosystemic shunt (TIPS) on pulmonary gas exchange and to evaluate the use of TIPS for the treatment of hepatopulmonary syndrome (HPS).METHODS: Seven patients, three of them with advanced HPS, in whom detailed pulmonary function tests were performed before and after TIPS placementat the University of Alabama Hospital and at the Hospital Clinic, Barcelona, were considered.RESULTS: TIPS patency was confirmed by hemodynamic evaluation. No changes in arterial blood gases were observed in the overall subset of patients. Transient arterial oxygenation improvement was observed in only one HPS patient, early after TIPS, but this was not sustained 4 mo later.CONCLUSION: TIPS neither improved nor worsened pulmonary gas exchange in patients with portal hypertension. This data does not support the use of TIPS as a specific treatment for HPS. However, it does reinforce the view that TIPS can be safely performed for the treatment of other complications of portal hypertension in patients with HPS.

Comparative Analysis of Budesonide Treatments on Blood Gas and Inflammation in Chronic Obstructive Pulmonary Disease Remission

Objective:To investigate the effects of budesonide on blood gas and inflammation indexes in patients with chronic obstructive pulmonary disease(COPD)during remission.Methods:Fifty-one patients with COPD in remission,admitted to Zhongshan Hospital of Dalian University from July 2021 to December 2022,were selected and divided into two groups based on a randomized numerical table method.The control group(25 cases)received budesonide formoterol treatment,while the observation group(26 cases)received budesonide geforce treatment.Various indexes,including clinical efficacy,blood gas indexes,inflammation indexes,St.George’s Respiratory Questionnaire(SGRQ)scores,Chronic Obstructive Pulmonary Disease Assessment Test(CAT)scores,and 6-minute Walking Distance Test(6MWD)results,were compared between the two groups.Results:After 21 days of treatment,the total clinical effectiveness rate of the observation group was higher than that of the control group,with a statistically significant difference(P<0.05).Post-treatment,the PaO2 level and pH value in both groups were higher,and the PaCO_(2) level was lower compared to pre-treatment levels.The observation group showed better improvements in these indicators than the control group,with statistically significant differences(P<0.05).SGRQ and CAT scores for both groups were lower post-treatment,with the observation group scoring lower than the control group.Additionally,the 6MWD results were farther for both groups post-treatment,with the observation group achieving greater distances than the control group,with statistically significant differences(P<0.05).Conclusion:Budesonide can effectively improve blood gas indexes in patients with COPD in remission,alleviate related clinical symptoms,reduce inflammatory responses,and promote patient recovery.The treatment efficacy is significant.

Comparative Gas Exchange of Ulmus crassifolia (Cedar Elm, Ulmaceae) and Ungnadia speciosa (Mexican Buckey, Sapindaceae) at Ambient and Elevated Levels of Light, CO2 and Temperature

Ulmus crassifolia Nutt. (Cedar elm, Ulmaceae) is a tree found in central and east Texas, northern Mexico, east to Florida, and north to southern Missouri and Oklahoma. Ungnadia speciosa Endl. (Mexican-buckeye, Sapindaceae) is a shrub or small tree found in woodlands and savannas of central and western Texas, southern New Mexico and northern Mexico. In central Texas, both species are found in Juniperus ashei/Quercus virginiana woodlands or savannas or also at low density in inter-canopy grassland gaps or patches. Environmental conditions in this area are stressful because of shallow soils, high summer temperatures, and inconsistent low rainfall. Currently, both species have a low density in these areas, and Ulmus crassifolia is usually a tree, while Ungnadia speciosa is a woody understory shrub. This study suggests U. crassifolia and U. speciosa are tolerant or intermediate species, with juveniles starting in shade. Maximum photosynthetic rate (Amax), dark respiration (Rd), intercellular CO2, light saturation (Lsp) and water use efficiency significantly increased when light levels and CO2 concentrations were elevated for both species, but not when temperatures were elevated. Stomatal conductance decreased when the CO2 concentration doubled, but there were few effects from elevated temperature. These findings suggest that U. speciosa and U. crassifolia should be more common and imply that they will have a higher density in a future high CO2 environment.

Effects of Combined Inhalation of Budesonide,Formoterol,and Tiotropium Bromide on Arterial Blood Gas and Pulmonary Function Indexes in Patients with Chronic Obstructive Pulmonary Disease

Objective:To analyze the effect of combined inhalation of budesonide formoterol and tiotropium bromide on arterial blood gas and pulmonary function indexes in patients with chronic obstructive pulmonary disease(COPD).Methods:100 patients with COPD treated from January to December 2022 were selected as observation objects,and were divided into a control group(n=50,in which budesonide and formoterol were administered)and an experimental group(n=50,the treatment drug was budesonide formoterol combined with tiotropium bromide)according to the computer grouping method,and compared the treatment results.Results:(i)Before treatment,there was no difference in the partial pressure of carbon dioxide and partial pressure of oxygen between the control group and the experimental group(P>0.05);after treatment,the partial pressure of carbon dioxide and partial pressure of oxygen in the experimental group were higher than those in the control group,with significant differences(P<0.05).(ii)Before treatment,there was no difference in forced vital capacity(FVC),forced expiratory volume in one second(FEV1),FEV1/FVC between the control group and the experimental group(P>0.05);after treatment,the FVC,FEV1,and FEV1/FVC in the experimental group were significantly higher than those in the control group(P<0.05).(iii)There was no difference in the levels of CRP,IL-6,and TNF-αbetween the control group and the experimental group(P>0.05);after treatment,the levels of CRP,IL-6,and TNF-αin the experimental group were lower than those in the control group,with significant differences(P<0.05).(iv)Compared to the total incidence of adverse reactions in the control group(28.00%),the incidence of total adverse reactions in the experimental group was lower at 10.00%,and the difference was significant(P<0.05).Conclusion:The combined inhalation of budesonide and formoterol with tiotropium bromide has demonstrated a clear therapeutic efficacy and safety in treating chronic obstructive pulmonary disease.This treatment approach effectively enhances arterial blood gas levels and lung function,showing promising potential for widespread application.

Photosynthetic Gas Exchange and Leaflet Movement of Robinia pseudoacacia in Relation to Changing Light Environments

On the sunny days, there were little diurnal changes in both azimuth and directional angle for either sun_ or shade_leaflet. However, there existed a significant diurnal change in midrib angle that reflected movements regarding evasion of light stress around noon hours. On the cloudy day, a very little diurnal difference was found in azimuth, directional and midrib angle. It is suggested that changing light environment is the main factor for inducing leaflet movement of Robinia pseudoacacia , and the rhythmical movement does not attribute to the leaflet movement. Leaf orientation control test showed that the photosynthetic rate ( Pn ), stomatal conductance ( g s ) and transpiration ( Tr ) of the artificial fixed_leaflets were significantly lower than that of control_leaflets. And the leaf temperature ( Tl ) of the fixed leaflets significantly exceeded that of control_leaflets, which may attribute to the significant difference of light interception between the fixed and control_leaflets. The light_dependent leaflet movement is the morphological adjustment of maintaining optimal physiological status.

Model of gas exchange dynamics for modified-atmosphere packages containing fresh produce

A model for modified-atmosphere packaging （MAP） systems containing fruits and vegetables was developed.The computer simulation was performed to predict the gas mass concentrations inside the packages and was successfully verified by experiments with yellow peaches at 5,15 and 25 ℃ using two types of packaging films.A Michaelis-Menten type respiration model with noncompetitive inhibition mechanism due to CO2 was adopted while the respiration rates were measured with an improved permeable system method suitable for either steady or unsteady state.The applicability of the model in the design of MAP systems was demonstrated with a calculation to evaluate film specification and equilibrium concentrations of O2 and CO2 in the package containing yellow peaches.

Effects of Nitrogen Application on Chlorophyll Fluorescence Parameters and Leaf Gas Exchange in Naked Oat

Naked oat（Avena nuda L.） was originated from China,where soil nitrogen（N） is low availability.The responses of chlorophyll（Chl.） fluorescence parameters and leaf gas exchange to N application were analysed in this study.After the N application rate ranged from 60 to 120 kg ha-1,variable fluorescence（F v）,the maximal fluorescence（F m）,the maximal photochemical efficiency（F v /F m）,quantum yield（Φ PS II） of the photosynthetic system II（PS II）,electron transport rate（ETR）,and photochemical quenching coefficient（qP） increased with N application level,however,non-photochemical quenching coefficient（qN） decreased.Moreover,there was no difference in initial fluorescence（F o） with further more N enhancement.The maximum net photosynthetic rate（P max）,apparent dark respiration rate（R d） and light saturation point（LSP） were improved with 40-56 kg N ha-1as basal fertilizer and 24-40 kg N ha-1as top dressing fertilizer applied at jointing stage.Initial quantum yield（α） was decreased with 24 kg N ha-1as basal fertilizer and 56 kg N ha-1as top dressing fertilizer.Flag-leaf net photosynthetic rate（P n） was significantly enhanced at the jointing and heading stages with 40-56 kg N ha-1as basal fertilizer; in addition,increased at grain filling stage of naked oat with 40-56 kg N ha-1as top dressing fertilizer.90 kg N ha-1（50-70% as basal fertilizer and 30-50% as top dressing fertilizer） application is recommended to alleviate photodamage of photosystem and improve the photosynthetic rate in naked oat.

Effect of Shading on Gas Exchange of Cotton Leaves Under Conditions of Different Soil Water Contents

Effect of different shading levels (no-shading, 80% shading, and 40% shading) on photosynthetic and stomatal responses in cotton leaves were investigated under conditions of different soil water contents in summer midday. All cotton leaves exhibited similar basic responses to shading, including decreased net photosynthetic rates, a tendency to decrease in transpiration rates, and increased stomatal conductance and intercellular CO2 concentration. The leaf conductance of 80% shaded and 40% shaded plants increased by 28% and 16.7% compared with no-shaded plants at high water, respectively, but the net photosynthetic rates of 80% shaded and 40% shaded plants declined by 50% and 14.73%, respectively. Results showed that combined effect of soil moisture and shading on photosynthetic and stomatal responses in cotton leaves was very remarkable.

Effects of soil drought stress on photosynthetic gas exchange traits and chlorophyll fluorescence in Forsythia suspensa

To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture,soil water conditions were controlled in greenhouse pot experiments using 2-year-old seedlings of Forsythia suspensa（Thunb.） Vahl. Photosynthetic gas exchange and chlorophyll fluorescence variables were measured and analyzed under 13 gradients of soil water content. Net photosynthetic rate（PN）, stomatal conductance（gs）, and water-use efficiency（WUE） in the seedlings exhibited a clear threshold response to the relative soil water content（RSWC）. The highest PNand WUEoccurred at RSWCof51.84 and 64.10%, respectively. Both PNand WUEwere higher than the average levels at 39.79% B RSWCB 73.04%. When RSWCdecreased from 51.84 to 37.52%,PN, gs, and the intercellular CO2 concentration（Ci）markedly decreased with increasing drought stress; the corresponding stomatal limitation（Ls） substantially increased, and nonphotochemical quenching（NPQ） also tended to increase, indicating that within this range of soil water content, excessive excitation energy was dispersed from photosystem II（PSII） in the form of heat, and the reduction in PNwas primarily due to stomatal limitation.While RSWCdecreased below 37.52%, there were significant decreases in the maximal quantum yield of PSII photochemistry（Fv/Fm） and the effective quantum yield of PSII photochemistry（UPSII）, photochemical quenching（qP）, and NPQ; in contrast, minimal fluorescence yield of the dark-adapted state（F0） increased markedly. Thus,the major limiting factor for the PNreduction changed to a nonstomatal limitation due to PSII damage. Therefore, an RSWCof 37.52% is the maximum allowable water deficit for the normal growth of seedlings of F. suspensa, and a water content lower than this level should be avoided in field soil water management. Water contents should be maintained in the range of 39.79% B RSWCB 73.04% to ensure normal function of the photosynthetic apparatus and high levels of photosynthesis and efficiency in F.suspensa.

Gas exchange of Rhodiola sachalinensis transplanted from different habitats in Changbai Mountain

Rhodiola sachalinensis growing in the different habitats, Xiaotianchi plot (altitude 1800 m), Tree line plot (altitude 2000 m) and Tianwenfeng plot (altitude 2325 m), of Changbai Moutain (northern slop) were transplanted to Harbin Experimental Forest Farm for measuring its characteristic of gas exchange. The study results indicated that the growth state and gas exchange characteristics ofRh. sachalinensis growing in different habitats varied markedly. The plants transplanted from Tianwenfeng plot had the highest values in net photosynthesis rate (Pn) and transpiration rate (Tr), those transplanted from Tree line plot shows the second, and those transplanted rom Xiaotianchi plot had the lowest values. The variance existed in transplanted plants was the same as shown in the field. From the result it can be extrapolated that the difference of Pn and Tr existed inRh. sachalinensis transplanted from different habitats is depend not only on the environmental factors, but on the variance of physiological characteristic of plant itself.

Diurnal change of gas exchange of Rhodiola sachalinensis transplanted from different habitats in Changbai Mountain

Rhodiola sachalinensis growing in the different habitats, such as Xiaotianchi plot (altitude 1800 m), Tree line plot (altitude 2000 m) and Tianwenfeng plot (altitude 2325 m) of Changbai Mountain (northern slop) were transplanted to Harbin Experimental Farm for determining its gas exchange. The study results indicated that the diurnal changes of gas exchange ofRh. sachalinensis transplanted from different habitats were still different though the morphological appearance of the newly sprouted above-ground part had become more similar. For net photosynthesis rate (Pn), stomatal conductance (Gs) and apparent quantum yield (AQY), the diumal change curves ofRh. sachalinensis transplanted from the three plots were similar, but the data value were different. For the dark respiration rate (Rd), transpiration rate (Tr) and water use efficiency (WUE), diurnal change curves of the three plots were obviously different.

Three-dimensional transient numerical simulation for gas exchange process in a four-stroke motorcycle engine

Three-dimensional transient numerical simulation of gas exchange process in a four-stroke motorcycle engine with a semi-spherical combustion chamber with two tilt valves was studied. Combination of the grid re-meshing method and the snapper technique made the valves move smoothly. The flow structure and pattern in a complete engine cycle were described in detail. Tumble ratios around the x-axis and y-axis were analyzed. Comparison of computed pressure with experimental pressure under motored condition revealed that the simulation had high calculation precision; CFD simulation can be regarded as an im-portant tool for resolving the complex aerodynamic behavior in motorcycle engines.

Effect of Two Administration Routes of Shenmai Injection(参麦注射液)on Pulmonary Gas Exchange Function after Tourniquet-Induced Ischemia-Reperfusion

Objective： To compare the effect between nebulized and intravenous administration of Shenmai Injection （参麦注射液） on pulmonary gas exchange function of patients following tourniquet-induced lower limb ischemia-repeffusion. Methods： Thirty-eight patients scheduled for lower extremity surgery were randomized into three groups using the closed envelop method： Shenmai Injection was administered 30 min before tourniquet inflation by nebulization [0.6 mL/kg in 10 mL normal saline （NS）] in the nebulization group or by intravenous drip （0.6 mL/kg dissolved in 250 mL of 10% glucose） in the intravenous drip group, and equal volume of NS was given intravenously in the NS group; 15 in each group. Arterial blood gases were analyzed, serum levels of malonaldehyde （MDA） and interleukine-6 （IL-6） and interleukine-8 （IL-8） were determined using the method of thiobarbituric acid reaction and enzyme-linked immuno sorbent assay respectively just before tourniquet inflation （TO）, and at 0.5 h （T1）, 2 h （TZ）, 6 h （T3） after tourniquet deflation. Results： Compared with baselines at TO, MDA levels significantly increased at TZ, T3 in the NS group and at T3 in the nebulization group, and IL-6 and IL-8 levels were significantly increased at TZ, T3 in NS, the intravenous drip and the nebulization groups （P〈0.05）. Arterial pressure of oxygen （PaO2） at T3 was decreased, while alveolar- arterial oxygen tension showed difference （PA-aDO2） at T3 in the NS group; RI at T3 in both intravenous drip and the nebulization groups were enhanced （P〈0.05）. Compared with the NS group, MDA and IL-8 levels at TZ, T3, 11-6 at T3 in the intravenous drip group, and IL-8 at T3 in the nebulization group were all remarkably increased （P〈0.05）. Additionally, MDA level at T3 in the nebulization group was higher than that in the intravenous drip group （P〈0.05）. Conclusions： Intravenous administration of Shenmai Injection provided a better protective effect than nebulization in mitigating pulmonary gas exchange dysfunction in patients following tourniquet-induced limb ischemia-repertusion.

Leaf gas exchange and photosynthesis curves of Elymus nutans and Potentilla anserina under fencing and grazing conditions in the Qilian Mountains, Northwest China

Potentilla anserina L.and Elymus nutans Griseb.are dominant species in the subalpine meadows of China.Grazing is one of the most important factors that influence community structure and productivity of subalpine meadows.Understanding how grazing changes photosynthetic capability is essential for preservation and restoration of grasslands.However,information about the effects of grazing on photosynthetic capability remains inadequate.Experiments were conducted in fencing and grazing areas in the Qilian Mountains,Northwest China.The leaf gas exchange and photosynthetic curves of P.anserina and E.nutans were measured at different growth stages.Results showed that grazing decreased the values of leaf gas exchange parameters,such as net photosynthetic rate,stomatal conductance,transpiration rate,and intercellular CO2 concentration of P.anserina and E.nutans.In addition,grazing decreased the values of net photosynthetic rate-photosynthetically active radiation(PN-PAR)curve parameters,such as light-saturated net photosynthetic rate,apparent quantum efficiency,light compensation point,light saturation point,and dark respiration rate.Our results demonstrated that grazing was the primary limiting factor for photosynthesis of dominant grassland species in the study area.

Effect of 1-MCP on Gas Exchange and Carbohydrate Concentrations of the Cotton Flower and Subtending Leaf under Water-Deficit Stress

Ethylene is an endogenous plant hormone that increases under adverse environmental conditions, resulting in leaf and fruit abscission and ultimately yield reduction. In cotton, however, the effects of water-deficit stress on ethylene production have been uncertain. In this study it was hypothesized that application of an ethylene inhibitor 1-Methylcyclo- propene (1-MCP) would prevent ethylene production and result in alleviation of water-deficit stress consequences on the physiology and metabolism of the cotton flower and subtending leaf. To test this hypothesis, growth chamber experiments were conducted in 2009-2010 with treatments consisting of (C) untreated well-watered control, (C + 1MCP) well-watered plus 1-MCP, (WS) untreated water-stressed control, and (WS + 1MCP) water-stressed plus 1-MCP. The plants were subjected to two consecutive drying cycles during flowering, approximately 8 weeks after planting, and 1-MCP was foliar applied at a rate of 10g. ai/ha at the beginning of each drying cycle. The results showed that 1-MCP application had no significant effect on gas exchange functions and did not prevent reductions from water stress in leaf photosynthesis, respiration and stomatal conductance. However, application of 1-MCP resulted in a decrease in sucrose content of water-stressed pistils compared to the control indicating that 1-MCP has the potential to interfere in carbohydrate metabolism of reproductive units.

Effects of Suhuang Zhike Capsule on Pulmonary Function, Blood Gas Analysis Index, Serum PCT and CRP Expression in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

OBJECTIVE: To observe the effects of Suhuang Zhike Capsule on pulmonary function, blood gas analysis index, serum PCT and CRP expression in patients with acute exacerbation of chronic obstructive pulmonary disease. METHODS: A total of 88 patients with acute exacerbation of chronic obstructive pulmonary disease admitted to the Department of Respiratory Medicine, Xuancheng People's Hospital of Anhui Province from December 2014 to December 2016 were randomly divided into the observation group and the control group, with 44 cases in each group. The control group was given routine clinical treatment, and the observation group was given Suhuang Zhike Capsule on the basis of the treatment method of the control group. After 7 days' treatment, the improvement of lung function indexes were observed and evaluated before and after treatment(forced expiratory volume in one second(FEV_1), forced expiratory volume occupancy in the 1^(st) second percentage of vital capacity(FEVl/FVC), peak expiatory flow(PEF)), blood gas analysis index(Arterial oxygen partial pressure(PaO_2) and arterial blood carbon dioxide partial pressure(PaCO_2), oxygenation index(OI)) and serum cytokine levels(procalcitonin(PCT) and C reactive protein(CRP). RESULTS: The total effective rate of the observation group was significantly higher than that of the control group(P < 0.05). The FEV_1, FEV_1/FVC and PEF in 2 groups were significantly increased after the treatment(P < 0.05), and the above lung function indexes in the observation group were significantly higher than the control group(P < 0.05). PaO_2 and OI were significantly increased after the treatment(P < 0.05), PaCO_2 was significantly decreased after the treatment(P < 0.05), and the improvement of above blood gas analysis indexes were significantly superior of the observation group than the control group(P < 0.05). The serum PCT and CRP levels in 2 groups were significantly decreased after the treatment(P < 0.05), and the improvement in the observation group were more significant than that in the control group(P < 0.05). CONCLUSION: Suhuang Zhike Capsule can inhibit serum inflammatory cytokine levels in patients with acute exacerbation of chronic obstructive pulmonary disease, improve blood gas analysis indicators, and improve lung functions.

Effects of naloxone hydrochloride on pulmonary function, blood gas changes and inflammatory factors in patients with COPD combined with respiratory failure

Objective: To investigate the effects of naloxone hydrochloride on pulmonary function, blood gas changes and inflammatory factors in patients with COPD combined with respiratory failure. Methods: According to random data table method, 80 cases of COPD combined with respiratory failure were randomly divided into the control group (n=40) and observation group (n=40), patients in the control group were treated with noninvasive positive pressure ventilation on the basis of routine symptomatic treatment, on the basis of the treatment of the control group, the observation group received naloxone hydrochloride therapy. The levels of pulmonary function, blood gas changes and inflammatory factors were compared in two groups before and after treatment. Results: The levels of serum FEV1, FVC, PEF, PaCO2, PaO2, PaO2/FiO2, TNF-α and PCT in the two groups before treatment were not statistically significant. After treatment, the levels of FEV1, FVC, PEF in the control group and observation group were (70.01±0.36)%, (2.16±0.41) L, (2.98±0.45) L/s and (81.71±0.53)%, (3.65±0.55) L, (4.36±0.43) L/s, which were significantly higher than those in the same group before treatment, and the levels in observation group were significantly higher than those in the control group;the levels of PaCO2, PaO2 and PaO22/FiO2 in the two groups were (59.62±6.47) mmHg, (65.53±7.36) mmHg, (323.89±10.47) and (46.59±6.64) mmHg, (73.65±8.26) mmHg, (398.64±14.06), compared with the same group before treatment, PaCO2 levels were significantly lower in both groups, and the observation group was significantly lower than the control group, PaO2,PaO2/FiO2 levels were significantly increased in both groups, and the observation group was significantly higher than the control group;the levels of TNF-α, PCT in the two groups were (23.28±4.53) pg/mL, (5.22±2.13) ng/mL and (16.61±4.12) pg/mL, (2.07±1.21) ng/mL, which were significantly lower than those in the same group before treatment, moreover, the observation group levels were significantly lower than those in the control group. Conclusion:Treatment of COPD with respiratory failure by naloxone hydrochloride can effectively reduce the level of inflammatory factors, and improved lung function and blood gas levels, which has important clinical value.

Responses of leaf water potential and gas exchange to the precipitation manipulation in two shrubs on the Chinese Loess Plateau

Regulation of leaf gas exchange plays an important role in the survival of trees and shrubs under future climate change. However, the responses of leaf water potential and gas exchange of shrubs in semi-arid areas to the precipitation alteration are not clear. Here, we conducted a manipulated experiment with three levels of precipitation, i.e., a control with ambient precipitation, 50% above ambient precipitation(irrigation treatment), and 50% below ambient precipitation(drought treatment), with two common shrubs, Salix psammophila C. Wang & C. Y. Yang(isohydric plant, maintaining a constant leaf water potential by stomatal regulation) and Caragana korshinskii Kom.(anisohydric plant, having more variable leaf water potential), on the Chinese Loess Plateau in 2014 and 2015. We measured the seasonal variations of predawn and midday leaf water potential(Ψpd and Ψmd), two parameters of gas exchange, i.e., light-saturated assimilation(An) and stomatal conductance(gs), and other foliar and canopy traits. The isohydric S. psammophila had a similar An and a higher gs than the anisohydric C. korshinskii under drought treatment in 2015, inconsistent with the view that photosynthetic capacity of anisohydric plants is higher than isohydric plants under severe drought. The two shrubs differently responded to precipitation manipulation. Ψpd, An and gs were higher under irrigation treatment than control for S. psammophila, and these three variables and Ψmd were significantly higher under irrigation treatment and lower under drought treatment than control for C. korshinskii. Leaf water potential and gas exchange responded to manipulated precipitation more strongly for C. korshinskii than for S. psammophila. However, precipitation manipulation did not alter the sensitivity of leaf gas exchange to vapor-pressure deficit and soil moisture in these two shrubs. Acclimation to long-term changes in soil moisture in these two shrubs was primarily attributed to the changes in leaf or canopy structure rather than leaf gas exchange. These findings will be useful for modeling canopy water-carbon exchange and elucidating the adaptive strategies of these two shrubs to future changes in precipitation.

Fluoride Exposure Compromises Gas Exchange of Plants

Fluorine (F-) stands out for its phytotoxic potential, because it accumulates in plants, changes enzymes activity, reduces chlorophyll content and, consequently, affects growth and yield of crop plants. An experiment was conducted to evaluate the effects of F- on leaf gas exchange in coffee and sweet orange plants, compared to sensitive (gladiolus) and tolerant (ryegrass) reference species. Plants grown in pots were exposed to F- in a semi-open mist chamber. The experimental design was completely randomized with treatments defined by the combination of plant species and two intensities of exposure to atmospheric F, with nebulization of HF solutions (low = 0.065 mmol·m-3 and high = 0.260 mmol·m-3) in a mist chamber, as well as with non-exposed control samples. CO2 assimilation (A), transpiration (E), stomatal conductance (gs) and chlorophyll fluorescence rates were measured after 27 days of treatment application. The leaf gas exchange variables in ryegrass and orange plants did not vary in response to the increase in atmospheric F, while an increase in gs and E values was observed in gladiolus and coffee plants. A decrease in A and potential quantum efficiency of photosystem II (Fv/Fm) was found for gladiolus plants. On the contrary, an increase of A for coffee plants was associated with the apparent effect previously reported about the loss of leaf stomatal regulation related to the short assessment period of plants in this experiment. Damages caused to the photosynthetic system were reflected in the susceptibility of the evaluated species to the contamination by the element.

Characteristics of Gas Exchange in Three Domesticated Anemone Species

Seeds of three Anemone species were collected from the suburban areas of Kunming and planted in a nursery for three and a half years at Kunming, Yunnan Province, China. Leaf gas exchange measurement indicated that these species had similar one-peak diurnal trends of net photosynthetic rate (PN), although A. rivularis had lower transpiration rate (TR), stomatal conductance (gs) and intercellular CO2 concentration (Ci), and higher stomatal limit in the afternoon. Species differences in response of PN to photosynthetically active radiation (PAR) were observed, especially under strong light. A. rivularis had the highest PN and Ci under strong light which corresponded with its highest gs and TR. A. rivularis had the highest light saturation point (LSP) (1000 mol m-2 s-1) and light compensation point (LCP) (69 mol m-2 s-1), while A. hupehensis var. japonica had the lowest LSP (800 ?mol m-2 s-1) and a lower LCP (53 mol m-2 s-1). But the three species responded similarly to the change of CO2 concentration in the air from 0 to 350 ?mol (CO2) mol-1, and their observed CO2 compensation point showed little difference (47, 53 and 56 ?mol (CO2) mol-1). Moreover, A. rivularis had the highest apparent quantum yield (0.032), carboxylation efficiency (0.049), PN (11.68 ?mol (CO2) m-2 s-1) and TR (5.36 mmol (H2O) m-2 s-1) based on the PN -PAR response. The results implied that A. rivularis is able to grow well under higher radiation, while A. hupehensis var. japonica is the best one to grow under partial shade.