Effects Of CO2 Enrichment Research Articles

Enhanced CO2 Adsorption and Conversion in Diethanolamine‐Cu Interfaces Achieving Stable Neutral Ethylene Electrosynthesis

AbstractMolecular modifications have shown tremendous potential in boosting the electrochemical CO2 reduction (CO2RR) to ethylene. However, the key mechanisms of modulation at the molecular level remain unclear, especially for the adsorption and activation of key intermediates (e.g., *CO2 and *CO). Here, report that a diethanolamine (DEA)‐modified Cu catalyst can reduce CO2 to ethylene with a faradaic efficiency of ≈50.5% with a partial current density of ≈155.7 mA cm−2 in the neutral conditions, which surpasses the Cu catalyst without molecular modification (≈28.5% and ≈95.6 mA cm−2). Density functional theory calculations demonstrate that DEA on the Cu surface boosts the adsorption and activation of CO2 and the following C–C coupling processes during the CO2RR‐to‐ethylene process. Molecular dynamics simulations suggest that the molecules distant from the Cu site have a CO2 enrichment effect. Operational stability achieved via the introduction of DEA molecules onto ketjen black, which then successively immobilized on the Cu nanoparticles and polytetrafluoroethylene electrodes to obtain a stable tripe‐phase boundary, realizing constant ethylene selectivity for 100 operating hours in a flow cell.

Effects of experimental CO2 enrichment on the PSII photochemical efficiency of Symbiodinium sp. in Acropora millepora

Enrichment of seawater with CO2 decreases the concentration of the carbonate ion while increasing that of hydrogen and bicarbonate ions. We use pulse-amplitude-modulation (PAM) fluorometry to investigate whether, in the absence of warming, and in sub-saturating light, these changes affect the PSII photochemical efficiency of _Symbiodinium_ sp. in the reef-building coral _Acropora millepora_. We assessed this experimentally with 30-min-interval saturation pulse analyses at 25 °C, a daily peak in the intensity of the photosynthetically active radiation (PAR) at ~65 µmol quanta m–2 s–1, and a seawater _p_CO2 that we gradually increased over nine days from ~496 to ~1290 μatm by injection of CO2-enriched air. Nine 14-day time series, which, except one, were recorded at the growing apices of a coral branch, revealed diel oscillations in the PSII photochemical efficiency characterized by a steep nocturnal decrease followed by a steep increase and peak in the morning, a daily minimum at midday (∆F/Fm’,midday), and a daily maximum at the onset of darkness at 19:00 h (Fv/Fm,19:00 h). An inadvertent shift in the position of one of the PAM fluorometer measuring heads revealed differences between the basal part and the growing coral apices of a coral branch in ∆F/Fm’midday and Qm. In ambient seawater (Control) _Symbiodinium_ sp. exhibited a gradual decrease, over the course of the experiment, in ∆F/Fm’,midday, Fv/Fm,19:00 h, and the slope of the linear regression between the relative electron transport rate and the intensity of PAR (rETR/PAR). Although two of three successive experiments indicated that CO2 enrichment counteracted these trends, statistical analyses failed to confirm an influence of _p_CO2 on ∆F/Fm’,midday, Fv/Fm,19:00 h, and Qm, rendering this experiment inconclusive.

Performance Evaluation of Three Peanut Cultivars Grown under Elevated CO2 Concentrations

This study explored the performance and physiological responses of three commercially used peanut cultivars in Australian farming systems under ambient and elevated CO2 conditions, aiming to identify the most suitable genotype for dual-purpose (grain and graze) cropping experiments. The experiment utilized an open-top chamber (OTC) facility to regulate CO2 concentrations. The elevated CO2 (EC) treatment targeted approximately 650 ± 50 µmol mol−1, while both ambient CO2 (AC) and control plots operated at a concentration of approximately 400 µmol mol−1. Notably, control plots without chambers served as a reference for current CO2 and environmental conditions. In contrast, despite having the same ambient CO2 concentration, AC plots were enclosed in chambers, allowing for plant growth comparisons with EC plots with the same environmental conditions aside from CO2 levels. The analyses revealed significant effects of CO2 enrichment on peanut plants. In particular, the EC treatment led to enhanced photosynthetic rates (20% in Kairi, 31% in Holt, and 19% in Alloway), alongside reduced stomatal conductance (−55% in Kairi, −32% in Holt, and −40% in Alloway), transpiration, and increased water use efficiency compared to AC conditions. Elevated CO2 levels positively influenced pod yields in Kairi (+41%) and Alloway (+36%). However, CO2 enrichment did not significantly alter the protein content, total phenolic content, cupric-reducing antioxidant capacity, and ferric-reducing antioxidant power of peanut plant material. Furthermore, no significant differences were observed in the phytochemical composition among the three cultivars under ambient or elevated CO2 conditions. On the other hand, analysis of the fibre structure conducted on peanut stover harvested at plant maturity suggested potential declines in feedstock quality. Based on the findings of this research, further investigations and testing, including simulated grazing trials, will be carried out to identify a single breed line suitable for dual-purpose management under future elevated CO2 conditions.

The Effects of CO2 Enrichment on the Radial Growth of Pinus densiflora

The Effects of CO2 Enrichment on the Radial Growth of Pinus densiflora

Warming-Induced Stimulation of Soil N2O Emissions Counteracted by Elevated CO2 from Nine-Year Agroecosystem Temperature and Free Air Carbon Dioxide Enrichment.

Globally, agricultural soils account for approximately one-third of anthropogenic emissions of the potent greenhouse gas and stratospheric ozone-depleting substance nitrous oxide (N2O). Emissions of N2O from agricultural soils are affected by a number of global change factors, such as elevated air temperatures and elevated atmospheric carbon dioxide (CO2). Yet, a mechanistic understanding of how these climatic factors affect N2O emissions in agricultural soils remains largely unresolved. Here, we investigate the soil N2O emission pathway using a 15N tracing approach in a nine-year field experiment using a combined temperature and free air carbon dioxide enrichment (T-FACE). We show that the effect of CO2 enrichment completely counteracts warming-induced stimulation of both nitrification- and denitrification-derived N2O emissions. The elevated CO2 induced decrease in pH and labile organic nitrogen (N) masked the stimulation of organic carbon and N by warming. Unexpectedly, both elevated CO2 and warming had little effect on the abundances of the nitrifying and denitrifying genes. Overall, our study confirms the importance of multifactorial experiments to understand N2O emission pathways from agricultural soils under climate change. This better understanding is a prerequisite for more accurate models and the development of effective options to combat climate change.

Vegetation and Evapotranspiration Responses to Increased Atmospheric Vapor Pressure Deficit across the Global Forest

A forest is vulnerable to drought and plays important roles in the regulation of carbon and water cycling in a terrestrial ecosystem. Atmospheric vapor pressure deficit (VPD) has been identified as an increasingly major factor in plant functioning and has been established as a main contributor to recent drought-induced plant mortality, independent of other drivers associated with climate change. However, most previous studies have focused on the effects of climate warming and CO2 enrichment on vegetation growth, without considering the effects of an increased VPD on vegetation growth and evapotranspiration (ET) in forest ecosystems. This could lead to a large uncertainty in estimating the variability in forest carbon sinks. Based on the long-term satellite data, we investigated the response of the leaf area index (LAI) and ET to the VPD via a partial correlation analysis in this study. We also examined the temporal variability in the partial coefficients within a ten-year moving window. The results showed that over 50% of the region displayed a negative partial correlation between the LAI, ET, and VPD, and those pixels were mainly concentrated in North America and the plains of Eastern Europe. Regions with a negative trend of partial correlation in both the LAI and ET are mostly located in the plains of Eastern Europe and the Siberian Plain of western Russia, while the positive trend is mainly in South America. The plains of Eastern Europe are becoming drier, which was proved by the interannual trend of the Standardized Precipitation Evapotranspiration Index (SPEI) and soil water content (SWC). Additionally, the LAI and ET in those areas exhibited a significant positive correlation with the SWC based on the moving window average. This study suggests that the role of the VPD on vegetation will become increasingly prominent in the context of future climate change for the forest ecosystem.

Differential effects of elevated CO2 on awn and glume metabolism in durum wheat (Triticum durum).

While the effect of CO2 enrichment on wheat (Triticum spp.) photosynthesis, nitrogen content or yield has been well-studied, the impact of elevated CO2 on metabolic pathways in organs other than leaves is poorly documented. In particular, glumes and awns, which may refix CO2 respired by developing grains and be naturally exposed to higher-than-ambient CO2 mole fraction, could show specific responses to elevated CO2 . Here, we took advantage of a free-air CO2 enrichment experiment and performed multilevel analyses, including metabolomics, ionomics, proteomics, major hormones and isotopes in Triticum durum . While in leaves, elevated CO2 tended to accelerate amino acid metabolism with many significantly affected metabolites, the effect on glumes and awns metabolites was modest. There was a lower content in compounds of the polyamine pathway (along with uracile and allantoin) under elevated CO2 , suggesting a change in secondary N metabolism. Also, cytokinin metabolism appeared to be significantly affected under elevated CO2 . Despite this, elevated CO2 did not affect the final composition of awn and glume organic matter, with the same content in carbon, nitrogen and other elements. We conclude that elevated CO2 mostly impacts on leaf metabolism but has little effect in awns and glumes, including their composition at maturity.

Intensification of harmful cyanobacterial blooms in a eutrophic, temperate lake caused by nitrogen, temperature, and CO2

Warmer temperatures can significantly increase the intensity of cyanobacterial harmful algal blooms (CHABs) in eutrophic freshwater ecosystems. However, few studies have examined the effects of CO2 enrichment in tandem with elevated temperature and/or nutrients on cyanobacterial taxa in freshwater ecosystems. Here, we observed changes in the biomass of cyanobacteria, nutrients, pH, and carbonate chemistry over a two-year period in a shallow, eutrophic freshwater lake and performed experiments to examine the effects and co-effects of CO2, temperature, and nutrient enrichment on cyanobacterial and N2-fixing (diazotrophic) communities assessed via high throughput sequencing of the 16S rRNA and nifH genes, respectively. During both years, there were significant CHABs (50–500 μg cyanobacterial chlorophyll-a L−1) and lake CO2 levels were undersaturated (≤300 μatm pCO2). NH4+ significantly increased the net growth rates of cyanobacteria as well as the biomass of the diazotrophic cyanobacterial order Nostocales under elevated and ambient CO2 conditions. In a fall experiment, the N2 fixation rates of Nostocales were significantly higher when populations were enriched with CO2 and P, relative to CO2-enriched populations that were not amended with P. During a summer experiment, N2 fixation rates increased significantly under N and CO2 - enriched conditions relative to N-enriched and ambient CO2 conditions. Nostocales dominated the diazotrophic communities of both experiments, achieving the highest relative abundance under CO2-enriched conditions when N was added in the first experiment and when CO2 and temperature were elevated in the second experiment, when N2 fixation rates also increased significantly. Collectively, this study indicates that N promotes cyanobacterial blooms including those formed by Dolichospermum and that the biomass and N2 fixation rates of diazotrophic cyanobacterial taxa may benefit from enhanced CO2 levels in eutrophic lakes.

The spatiotemporal patterns and climate impacts of the carbon dynamics in economically developed areas of China during the past 40 years: A case of Jiangsu Province

Achieving carbon neutrality is currently the most important and urgent task in the field of ecological environment for China. However, the ecosystems carbon stock dynamic, carbon sequestration potential and main driving factors in the economically developed regions of China, Jiangsu Province in recent 40 years are still unclear. Existential quantification scale and interactive human-land coupling relationship pose a great challenge to identify the carbon dynamics pattern in economically developed regions in China. In this study, we used scenarios simulation and main control factor analysis method to identify the spatiotemporal pattern of carbon dynamics in the developed Jiangsu region from 1979 to 2018, and defined and evaluated the sensitivity of different ecosystems to different environmental factors. Furthermore, we separated and quantified the individual and interactive response characteristics of carbon stocks to different environmental factors, and the results showed that Jiangsu has experienced rapid climate change (warming rate +0.5 °C/10a), and warming is a key climate factor leading to a decrease in soil organic carbon (SOC), and decreased by −30.7 g C/m2 during the study period is greater than the promotion effect of precipitation (18.7 g C/m2).Vegetation carbon (VEGC) has no significant response to temperature and precipitation. The pattern of carbon dynamic shows significant spatial heterogeneity. On the whole, there is a trend of increasing carbon storage in coastal areas and decreasing carbon storage in urban agglomeration in southern Jiangsu. The factor analysis results indicate that the CO2 enrichment effect promotes the increase of carbon storage in different carbon reservoirs; The impact of climate change on different carbon pools mainly manifests as negative effects; The interactive effect is manifested as a positive effect, and the sensitivity of carbon stocks to the positive CO2 fertilization effect is greater than that to climate change. In the future, attention should be paid to the impact of double superposition of temperature increase and urban heat island effect on the carbon stocks of coastal wetlands and urban forest ecosystem in southern Jiangsu.

Effects of free air CO2 enrichment (FACE) on grain yield and quality of hybrid rice

ContextElevated atmospheric CO2 concentration (eCO2) impacts grain yield and quality of rice, but whether grains at different positions on a large panicle of hybrid rice respond differently to eCO2 is unclear. ObjectiveA 2-year field experiment was conducted to study eCO2-induced changes in grain yield and quality of hybrid rice, with emphasis on the differences between superior spikelets (SS) and inferior spikelets (IS). MethodsA hybrid indica cultivar YLY900 was exposed to ambient and elevated CO2 (+200 μmol mol−1) at a large free air CO2 enrichment (FACE) platform in two successive rice seasons. Grain yield, yield components, grain filling capacity and quality traits of SS and IS were measured. ResultsAveraged across two years, eCO2 increased grain yield of YLY900 by 15%, which was mainly due to enlarged spikelet density, especially that of secondary branches of panicles. Compared with rice season of 2017, low air temperature, overabundant rainfall and lack of light in the early growth stage in 2016 inhibited tillering formation, resulting in lower panicle density and reduced CO2 fertilization effect on grain yield (22% in 2017 vs. 9% in 2016). In general, grain filling capacity of SS was superior to that of IS, as shown by higher fully-filled grain percentage, larger grain size and grain weight. Grain quality of SS was better than that of IS in terms of less grain chalkiness, fewer green grains, and better cooking quality. However, the concentrations of P, K, Ca, Mg, S and Mn were lower in SS than IS. For both SS and IS, eCO2 decreased head rice percentage, grain N and S concentrations, but increased cooking quality as indicated by the changes in RVA profiles. No grain position by CO2 interactions on grain quality traits were detected except the grain appearance: SS had few green grains at either CO2 condition, but IS had a great portion of green grains, which was reduced by approximately 50% at eCO2. ConclusionsWeather conditions at the key growth stage of sink formation had a strong impact on the CO2 fertilization effect. Although grain quality of SS and IS differed significantly, their responses to CO2 elevation were similar except the eCO2-increased grain ripeness of IS. ImplicationsElevated CO2 may not be able to offset the yield loss caused by unfavorable weather conditions for rice growth, a proper adjustment in crop management is needed to improve rice yield and quality in future high CO2 environments.

Sensitivity of simulated soil water content, evapotranspiration, gross primary production and biomass to climate change factors in Euro-Mediterranean grasslands

Grassland models often yield more uncertain outputs than arable crop models due to more complex interactions and the largely undocumented sensitivity of grassland models to environmental factors. The aim of the present study was to assess the impact of single-factor changes in temperature, precipitation, and atmospheric [CO2] on simulated soil water content (SWC), actual evapotranspiration (ET), gross primary production (GPP) and yield biomass, and also to link the sensitivity analysis with experimental results. We employed an unprecedented multi-model framework consisting of seven grassland models at nine sites with different environmental characteristics in Europe and Israel, with two management options at three sites. For warming/cooling and wetting/drying, models showed general consistency in the direction of SWC and ET changes, but less agreement regarding GPP and biomass changes. The simulated responses consistently revealed an overall positive effect of CO2 enrichment on GPP and biomass, while the direction of change differed for SWC and ET. Comparing with single-factor experimental manipulations, SWC simulations slightly underestimated the observed effect of warming, while the overall mean model sensitivity for biomass (+7.5%) closely matched the mean response observed with 1–2 °C warming (+6.6%). The models exhibited lower sensitivity of SWC to wetting or drying compared to the experiments. The overall mean sensitivity of biomass to drying was -4.3%, contrasting with the mean experimental effect size of -9.6%, which proved to be more realistic than the mean wetting effect (+3.2%, against +38.9% in the field trials). The simulated sensitivity of SWC to CO2 enrichment was markedly underestimated, while the biomass response (+12.0%) closely matched the observations (+17.5%). Although the multi-model averaging did not manifestly improve the realism of the simulations, it ensured a realistic response in the direction of change to varying conditions. The results suggest a paradigm shift in grassland modelling meaning that the usual practice of model optimisation/validation needs to be complemented by a sensitivity analysis following the approach presented. The results also highlight the importance of model improvements, especially in terms of soil hydrology representation, a key environmental driver of grassland functioning.

CO2 enrichment and excess nitrogen supply synergistically increase toxicity of marine dinoflagellate Alexandrium minutum

Discharges of CO2 and nutrients by anthropogenic activities have notable contributions to CO2 enrichment and eutrophication in coastal systems. Following our previous study that toxic dinoflagellate Alexandrium minutum will increase their growth rate and cellular toxicity under elevated levels of CO2, we further examined the joint effects of CO2 enrichment and excess nitrogen supply through a 29-day experiment under three CO2 levels (400, 800 and 1200 ppm) with a high N/P ratio of 80. It was found that the two factors have synergistical effects in promoting the increase of cellular toxicity. There were remarkable increases in toxin biosynthesis of paralytic shellfish toxins when both intracellular and extracellular toxins were considered. Under the joint impacts of CO2 enrichment and excess nitrogen supply, the apparent transformation from gonyautoxins2/3 to gonyautoxins1/4, with much higher toxicity and lower rate of release, is likely to be another major factor accounting for the increasing toxicity. The increasing growth rate and cellular toxicity of A. minutum under the scenarios with elevated concentrations of both CO2 and nitrogen in coastal systems in the future will increase the risks associated with such toxic algal blooms.

Effect of Atmospheric CO2 Enrichment On Mineral Nutrient and Yield of Wheat Under Weed Competitive Pressure of Wild Oat

Effect of Atmospheric CO2 Enrichment On Mineral Nutrient and Yield of Wheat Under Weed Competitive Pressure of Wild Oat

Drought dampens the positive acclimation responses of leaf photosynthesis to elevated [CO2] by altering stomatal traits, leaf anatomy, and Rubisco gene expression in Pyrus

The responses of Chinese pear plantations to rising atmospheric CO2 concentration ([CO2]) and drought are crucial for accurately estimating pear production and forest carbon sink of China under future climate change. Here, we investigated the effect of CO2 enrichment on plant growth and leaf photosynthesis of Chinese pear trees grown under full irrigation and different levels of drought. We identified that leaf photosynthetic capacity and stomatal conductance increased by high [CO2] acclimation. However, such positive effects disappeared when drought occurred, especially under moderate and severe drought. This down-regulation of high [CO2] acclimation responses in leaf photosynthesis by drought was mainly caused by the decline in stomatal diffusional efficiency, thinner mesophyll tissues and smaller mesophyll cells. The decrease of stomatal diffusional efficiency was further caused by the reduced stomatal density and decreased regularity of stomatal distribution pattern under drought. Moreover, the down-regulation of those positive acclimation responses was relevant with the declines of carboxylation and photochemical efficiency of Rubisco, which was confirmed by the down-regulated expression levels of Rubisco coding genes. Overall, our results demonstrated that drought dampened the positive acclimation responses of leaf photosynthesis to elevated [CO2] by modifying stomatal morphology and distribution, leaf anatomy, and Rubisco gene expression. Therefore, under future climate change where CO2 enrichment is coupled with higher frequency of drought events, drought limitations should be incorporated into the current coupled climate-carbon models to avoid overestimation of the positive responses of Chinese pear plantations to elevated [CO2] and to accurately predict forest carbon sequestration.

Effects of CO2 Enrichment on Carbon Assimilation, Yield and Quality of Oriental Melon Cultivated in a Solar Greenhouse

Since CO2 is the fundamental substrate for photosynthesis, fluctuating concentrations have a direct effect on plant growth and metabolism. Accordingly, CO2 enrichment within a certain range was found to improve photosynthesis, yields and the quality of plants. In order to further understand the underlying impact of CO2 enrichment, this study employed an open-top chamber growth box model with the following two treatments: control treatment (CO2 concentration: 380 ± 30 μL/L) and CO2 enrichment (1200 ± 50 μL/L). The effects on leaf carbon assimilation, fruit yield and quality were subsequently determined. The net photosynthetic rate, intercellular CO2 concentration, dry matter accumulation and soluble sugar content in the oriental melon leaves increased significantly on day 5 of CO2 enrichment. Moreover, a significant increase in the activity of carbon assimilation-related enzymes Rubisco, RCA, FBPase and CA was also observed, with the upregulation of CmRubisco, CmRCA, CmFBPase and CmCA gene expression from day 15 of CO2 enrichment. Thus, the yield per plant and content of soluble sugars and soluble solids in the fruit also increased significantly. These findings suggest that CO2 enrichment has positive effects on oriental melon growth, increasing photosynthesis and the activity of photosynthetic carbon-assimilation-related enzymes and associated gene expression, thereby improving fruit yields and quality. These results provide a foundation for the CO2 enrichment of oriental melon cultivated in solar greenhouses in autumn/winter and winter/spring.

Precise Sensing of Leaf Temperatures for Smart Farm Applications

Leaf temperature represents the mixed effects of solar radiation, temperature, and CO2 enrichment on the potential production of greenhouse vegetables. However, smart farm applications that monitor and account for changes in leaf temperature are limited. This study developed new hardware and software components for leaf temperature sensing integrated into a conventional smart farm system. We demonstrated a new system to monitor leaf temperatures and improve crop yield at two greenhouse tomato and strawberry farms in South Korea. We observed a rapid decline in leaf temperature at both farms when the indoor air temperature decreased. This pattern often corresponds to stagnant CO2 assimilation. The results suggest that leaf temperature sensing is practical for slow aeration and heating that is required to optimize photosynthetic efficiency, especially in the morning and when leaf temperatures become high (over 25 °C). Specifically, smart farm implementation with leaf temperature sensing increased the yield of tomatoes by 28–43%. Furthermore, our study highlights the need to develop leaf temperature models for smart greenhouse farming that interact with nutrient and water supplies.

Evaluation of evapotranspiration models for cucumbers grown under CO2 enriched and HVAC driven greenhouses: A step towards precision irrigation in hyper-arid regions

Evapotranspiration is considered as one of the most crucial surface fluxes describing the water movement from the land to the atmosphere in the form of evaporation from the soil and transpiration from plants. Several evapotranspiration models exist, but their accuracy is subject to change because of the differences between the underlying assumptions used in their formulation and the conditions of the application at hand. The appropriate selection of an evapotranspiration model is necessary to ensure the accurate estimation of crop water requirements. This work compares between 20 different evapotranspiration models for the estimation of transpiration of cucumber crops grown in a cooling-based greenhouse with CO2 enrichment located in a high solar radiation region. The models are classified into temperature-based, radiation-based, mass transfer-based, and combination models. These models are assessed against direct gas exchange measurements in a greenhouse with cucumber crops. The performance of the models is evaluated using nine statistical indicators to determine the most suitable models for the application under study. Results demonstrate that among the temperature-based models, Schendel and Blaney and Criddle models resulted in the best transpiration prediction, contrary to Hargreaves and Samani which presented the worst performance. Transpiration estimates from Rohwer were the closest and that of Trabert were the furthest to the measured data amongst the other mass-transfer based models. The Abtew model was the best transpiration predicting model, while Priestley and Taylor exhibited the worst performance in the radiation-based model category. The combination-based FAO56 Penman Monteith entailed the best performance among all models and can be considered the best suitable method to estimate transpiration for cucumber crops grown in CO2 enriched and HVAC based greenhouses located in high solar radiation regions. Nonetheless, the parametrization of this model is still crucial and should be considered to achieve better estimates and accurately evaluate the effect of high solar radiation, CO2 enrichment and HVAC cooling for this agricultural greenhouse application.

Differential Effect of Free-Air CO2 Enrichment (FACE) in Different Organs and Growth Stages of Two Cultivars of Durum Wheat.

Wheat is a target crop within the food security context. The responses of wheat plants under elevated concentrations of CO2 (e[CO2]) have been previously studied; however, few of these studies have evaluated several organs at different phenological stages simultaneously under free-air CO2 enrichment (FACE) conditions. The main objective of this study was to evaluate the effect of e[CO2] in two cultivars of wheat (Triumph and Norin), analyzed at three phenological stages (elongation, anthesis, and maturation) and in different organs at each stage, under FACE conditions. Agronomic, biomass, physiological, and carbon (C) and nitrogen (N) dynamics were examined in both ambient CO2 (a[CO2]) fixed at 415 µmol mol-1 CO2 and e[CO2] at 550 µmol mol-1 CO2. We found minimal effect of e[CO2] compared to a[CO2] on agronomic and biomass parameters. Also, while exposure to 550 µmol mol-1 CO2 increased the photosynthetic rate of CO2 assimilation (An), the current study showed a diminishment in the maximum carboxylation (Vc,max) and maximum electron transport (Jmax) under e[CO2] conditions compared to a[CO2] at physiological level in both cultivars. However, even if no significant differences were detected between cultivars on photosynthetic machinery, differential responses between cultivars were detected in C and N dynamics at e[CO2]. Triumph showed starch accumulation in most organs during anthesis and maturation, but a decline in N content was observed. Contrastingly, in Norin, a decrease in starch content during the three stages and an increase in N content was observed. The amino acid content decreased in grain and shells at maturation in both cultivars, which might indicate a minimal translocation from source to sink organs. These results suggest a greater acclimation to e[CO2] enrichment in Triumph than Norin, because both the elongation stage and e[CO2] modified the source-sink relationship. According to the differences between cultivars, future studies should be performed to test genetic variation under FACE technology and explore the potential of cultivars to cope with projected climate scenarios.

Application of Hollow Fiber Membrane for the Separation of Carbon Dioxide from Atmospheric Air and Assessment of Its Distribution Pattern in a Greenhouse

Research on carbon management is fueled by the growing concern over rising carbon dioxide (CO2) levels in the atmospheric air and its possible impacts on the climate. In this study, we proposed a method of CO2 separation from atmospheric air. This study aimed to investigate the effects of CO2 enrichment on the air temperature inside a greenhouse using a hollow fiber (HF) membrane system. The experiment was conducted over a period of 30 days in two experimental conditions: 15 days without CO2 enrichment (WCS) and 15 days with CO2 enrichment (CS). Results showed that the mean CO2 concentration and air temperature were highest inside the greenhouse during the CS period, with values of 1120 ppm and 37.42 °C, respectively. Regression analysis revealed a positive correlation between CO2 concentration and temperature during the CS period (R2 = 0.628). The HF membrane system was found to be effective in increasing both the CO2 concentration and air temperature inside the greenhouse. However, the system also has limitations, including the cost, maintenance, and suitability for all types of crops. Further experiments are needed to address these limitations and determine the optimal CO2 concentration for different kinds of crops growing in greenhouses.

Multivariate drives and their interactive effects on the ratio of transpiration to evapotranspiration over Central Asia ecosystems

The ratio of vegetation transpiration to evapotranspiration (T/ET) characterizes the role of vegetation in surface-atmosphere interactions, affecting ecosystem productivity and the global carbon and water balances. Therefore, isolating and identifying the spatiotemporal characteristics of T/ET and its response to the individual and interactive effects of climatic factors will help us better understand the carbon and water cycle characteristics of ecosystems. The arid region of Central Asia has always been in the restricted area of ​​carbon-water cycle observations due to scarce station observations, harsh climatic conditions, and severe anthropogenic disturbances. Using a specific Arid Ecosystem Model (AEM), this study explored the temporal and spatial dynamic patterns of T/ET of different plant functional types (PFTs) in drylands of Central Asia based on multi-climate scenarios, and separated and quantified the independent and interactive effects of different environmental factors. The result indicated that precipitation dominated the areas of 86% (ET, evapotranspiration), 77% (T, transpiration), and 71% (the ratio of T/ET) in the arid region of Central Asia, respectively. The effect of temperature on the ratio of T/ET was negative and slight. And the temperature increase effect is only 9.7% of the negative effect of precipitation. Affected by the insignificant effect of CO2 enrichment on T, the interactive effect between climate change and CO2 effect appear to be little and negative. According to the vegetation growth and the spatial distribution of precipitation, we found that the southern Xinjiang region and the Turgay Plateau in northwestern Kazakhstan are the ecologically vulnerable areas in Central Asian. The results also indicated that general warming in this region may not have a direct and significant impact on vegetation T/ET in the future. We may need to pay more attention to the indirect effect of enhanced evaporation and reduced moisture on T/ET caused by future warming.