CO2 Gas Exchange Research Articles

Toward Modeling Continental‐Scale Inland Water Carbon Dioxide Emissions

AbstractInland waters emit significant amounts of carbon dioxide (CO2) to the atmosphere; however, the global magnitude and source distribution of inland water CO2 emissions remain uncertain. These fluxes have previously been “statistically upscaled” by independently estimating dissolved CO2 concentrations and gas exchange velocities to calculate fluxes. This scaling, while robust and defensible, has known limitations in representing carbon source limitations and spatial variability. Here, we develop and calibrate a CO2 transport model for the continental United States, simulating carbon transport and transformation in >22 million hydraulically connected rivers, lakes, and reservoirs. We estimate 25% lower CO2 fluxes compared to upscaling estimates forced by the same observational calibration data. While precise CO2 source distribution estimates are limited by the resolution of model parameterizations, our model suggests that stream corridor CO2 production dominates over groundwater inputs at the continental scale. Our results further suggest that the lack of observational networks for groundwater CO2 and scalable metabolic models of aquatic CO2 production remain the most salient barriers to further coupling of our model with other Earth system components.

Assessing sediment CO2 effluxes in the coastal ecosystem of North Sumatra, Indonesia

Coastal wetlands including mangrove play a vital role in regulating the local and global carbon cycle. Coastal areas contribute greatly to the carbon exchange process due to the complex interactions that occur between the atmosphere, land, and oceans. One of the important components in coastal carbon dynamics is CO2 gas exchange between soil, water and the atmosphere. This study aims to assess CO2 efflux across various land covers (namely natural mangrove, restored mangrove, and converted mangroves to oil palm and aquaculture pond) in the coastal areas of North Sumatra Province, and analyze the effect of sea tides and ebbs on the rate of CO2 efflux and their connection with the number and area of macrozoobenthos burrows. We applied direct sampling by using the static closed chamber method attached to portable CO2 analyzer. The mean of CO2 efflux in natural mangrove forest land covers was 866±585 mgCO2/m2/h during low tide conditions and 1137±792 mgCO2/m2/h during high tide conditions, followed by oil palm plantations at 760.71±341 mgCO2/m2/h, restored mangroves during low tide of 575.24±326 mgCO2/m2/h and 597.11±180 mg CO2/m2/h during high tide conditions, and the lowest was recorded in ponds at 588.55±358 mgCO2/m2/h. Further, we observed that tidal conditions affect the magnitudes of CO2 efflux in natural and restored mangrove forests, and we did not observe similar pattern in oil palms and ponds since these land covers were not influenced by regular tidal input. We also observed that no significant relationship between the number and area of macrozoobenthos burrows and CO2 efflux. Our findings suggest that CO2 effluxes in coastal wetlands are highly dynamic and presumably driven by complex factors and therefore, understanding their magnitudes and drivers requires extensive measurement covering large spatial and temporal scales.

The timing of the ca-660 BCE Miyake solar-proton event constrained to between 664 and 663 BCE

Extreme solar energetic particle events, known as Miyake events, are rare phenomena observed by cosmogenic isotopes, with only six documented. The timing of the ca. 660 BCE Miyake event remains undefined until now. Here, we assign its occurrence to 664–663 BCE through new radiocarbon measurements in gymnosperm larch tree rings from arctic-alpine biomes (Yamal and Altai). Using a 22-box carbon cycle model and Bayesian statistics, we calculate the radiocarbon production rate during the event that is 3.2–4.8 times higher than the average solar modulation, and comparable to the 774–775 CE solar-proton event. The prolonged radiocarbon signature manifests a 12‰ rise over two years. The non-uniform signal in the tree rings is likely driven by the low rate of CO2 gas exchange between the trees and the ambient atmosphere, and the high residence time of radiocarbon in the post-event stratosphere. We caution about using the event’s pronounced signature for precise single-year-dating.

Iron and Manganese concentrations in leaf tissues of Rhizophora mangle (Rhizophoraceae): implications for energetic metabolism

Introduction: Iron (Fe) and manganese (Mn) are bioessential micronutrients for plants but can impair the energetic metabolism when present at high levels. Objective: To assess the photosynthetic performance and oxidative damages in Rhizophora mangle L. leaf tissues at low and high concentrations of Fe (74 and 195 mg kg-1; Feleaf) and Mn (65 and 414 mg kg-1; Mnleaf). Methods: Photosynthetic pigments, chlorophyll a fluorescence, leaf CO2 assimilation and gas exchange and DPPH• radical scavenging capacity were sampled in R. mangle growing in estuarine forests in the North region of Espírito Santo State and the extreme South of Bahia State (Brazil) showing low and high Feleaf and Mnleaf. Results: Effects of high Fe and Mn were not identified on pigment levels. The increase in Feleaf and Mnleaf at the levels observed in this assessment had a positive effect on the number of reaction centers and on the efficiency of the oxygen-evolving complex, evaluated as K-band, while no changes were found in the parameters related to the excitation trapping efficiency at the active center of photosystem II. Distinct interference patterns of Fe and Mn on the functional processes of photosynthesis were identified, especially on CO2 assimilation and reactive oxygen species metabolism, with major effects on CO2 assimilation and carboxylation efficiency of Rubisco at high Mnleaf. Conclusion: These findings demonstrate the efficiency of R. mangle in positively regulating the electron transport chain in response to high Fe and Mn, at least in terms of the preservation of structure and functionality of the plant photosynthetic apparatus. Moreover, interference of high Mnleaf in R. mangle occurs at non-stomatal and biochemical levels. There is an antagonistic interference of these trace elements with the physiology of R. mangle, which is a dominant species in Brazilian mangroves.

The Ecosystem as Super-Organ/ism, Revisited: Scaling Hydraulics to Forests under Climate Change.

Classic debates in community ecology focused on the complexities of considering an ecosystem as a super-organ or organism. New consideration of such perspectives could clarify mechanisms underlying the dynamics of forest carbon dioxide (CO2) uptake and water vapor loss, important for predicting and managing the future of Earth's ecosystems and climate system. Here, we provide a rubric for considering ecosystem traits as aggregated, systemic, or emergent, i.e., representing the ecosystem as an aggregate of its individuals or as a metaphorical or literal super-organ or organism. We review recent approaches to scaling-up plant water relations (hydraulics) concepts developed for organs and organisms to enable and interpret measurements at ecosystem-level. We focus on three community-scale versions of water relations traits that have potential to provide mechanistic insight into climate change responses of forest CO2 and H2O gas exchange and productivity: leaf water potential (Ψcanopy), pressure volume curves (eco-PV), and hydraulic conductance (Keco). These analyses can reveal additional ecosystem-scale parameters analogous to those typically quantified for leaves or plants (e.g., wilting point and hydraulic vulnerability) that may act as thresholds in forest responses to drought, including growth cessation, mortality, and flammability. We unite these concepts in a novel framework to predict Ψcanopy and its approaching of critical thresholds during drought, using measurements of Keco and eco-PV curves. We thus delineate how the extension of water relations concepts from organ- and organism-scales can reveal the hydraulic constraints on the interaction of vegetation and climate and provide new mechanistic understanding and prediction of forest water use and productivity.

On the short-term response of entrained air bubbles in the upper ocean: a case study in the north Adriatic Sea

Abstract. Air bubbles in the upper ocean are generated mainly by waves breaking at the air–sea interface. As such, after the waves break, entrained air bubbles evolve in the form of plumes in the turbulent flow, exchange gas with the surrounding water, and may eventually rise to the surface. To shed light on the short-term response of entrained bubbles in different stormy conditions and to assess the link between bubble plume penetration depth, mechanical and thermal forcings, and the air–sea transfer velocity of CO2, a field experiment was conducted from an oceanographic research tower in the north Adriatic Sea. Air bubble plumes were observed using high-resolution echosounder data from an upward-looking 1000 kHz sonar. The backscatter signal strength was sampled at a high resolution, 0.5 s in time and 2.5 cm along the vertical direction. Time series profiles of the bubble plume depth were established using a variable threshold procedure applied to the backscatter strength. The data show the occurrence of bubbles organized into vertical plume-like structures, drawn downwards by wave-generated turbulence and other near-surface circulations, and reaching the seabed at 17 m depth under strong forcing. We verify that bubble plumes adapt rapidly to wind and wave conditions and have depths that scale approximately linearly with wind speed. Scaling with the wind–wave Reynolds number is also proposed to account for the sea-state severity in the plume depth prediction. Results show a correlation between measured bubble depths and theoretical air–sea CO2 transfer velocity parametrized with wind-only and wind/wave formulations. Further, our measurements corroborate previous results suggesting that the sinking of newly formed cold-water masses helps bring bubbles to greater depths than those reached in stable conditions for the water column. The temperature difference between air and sea seems sufficient for describing this intensification at the leading order of magnitude. The results presented in this study are relevant for air–sea interaction studies and pave the way for progress in CO2 gas exchange formulations.

83 Automated PDMS Engraving and Assembly of a Prototype Microfluidic Artificial Lung

OBJECTIVES/GOALS: We report an automated manufacturing system, and a series of cylindrical multi-layer microfluidic artificial lungs manufactured with the system and tested for fluidic fidelity and function. METHODS/STUDY POPULATION: A Roll-to-Roll (R2R) system to engrave multiple-layer devices was assembled. A 100 um-thick silicone sheet passes through an embedded CO2 laser engraver, which creates patterns of any geometry on the surface. The sheet is plasma-activated to create an irreversible bond, and rerolled into a processed device. Unlike typical applications of R2R, this process is synchronized to achieve consistent radial positioning. This allows the fluidics in the device to be accessed without being unwrapped. The result is a cylindrical core surrounded by many layers of microfluidic channels that can be accessed through the side of the device or through fluidic vias. This core is cut to expose the microfluidic layers, and then installed into a housing which routes the fluids into their respective microfluidic flow paths. RESULTS/ANTICIPATED RESULTS: To demonstrate the capabilities of the R2R manufacturing system, this method was used to manufacture multi-layer microfluidic artificial lungs (µALs). Gas and blood flow channels are engraved in alternating layers and routed orthogonally. The close proximity of gas and blood separated by gas-permeable PDMS permits CO2 and O2 exchange. Three µALs were successfully manufactured. Their flow paths were visualized using dyed water and checked for leaks. Then they were evaluated using water for pressure drop and CO2 gas-exchange. The top performing device had 15 alternating blood and gas layers. Test with whole blood demonstrated oxygenation from venous (70%) saturation levels to arterial (95%) saturation levels at a flow rate of 3 ml/min. DISCUSSION/SIGNIFICANCE: The ability to cost-effectively produce high surface area microfluidic devices would bring many small-scale technologies from the realm of research to clinical and commercial applications. In particular, most microfluidic artificial lungs only have small rated flows due to a lack of manufacturing processes able to create high surface area devices.

Physiological responses of low- and high-cadmium accumulating Robinia pseudoacacia-rhizobium symbioses to cadmium stress

The role of rhizobia in alleviating cadmium (Cd) stress in woody legumes is still unclear. Therefore, two types of black locust (Robinia pseudoacacia L.) with high and low Cd accumulation abilities were selected from 11 genotypes in China, and the effects of rhizobium (Mesorhizobium huakuii GP1T11) inoculation on the growth, CO2 and H2O gas exchange parameters, Cd accumulation, and the absorption of mineral elements of the high (SX) and low Cd-accumulator (HB) were compared. The results showed that rhizobium-inoculation significantly increased biomass, shoot Cd contents, Cd accumulation, root-to-shoot translocation factor (TF) and the absorption and accumulation of mineral elements in both SX and HB. Rhizobium-inoculation increased chlorophyll a and carotenoid contents, and the intercellular carbon dioxide concentrations in HB plants. Under Cd exposure, the high-accumulator SX exhibited a significant decrease in photosynthetic CO2 fixation (Pn) and an enhanced accumulation of Cd in leaves, but coped with Cd exposure by increasing chlorophyll synthesis, regulating stomatal aperture (Gs), controlling transpiration (Tr), and increasing the absorption and accumulation of mineral elements. In contrast, the low-accumulator HB was more sensitive to Cd exposure despite preferential accumulation of Cd in roots, with decreased chlorophyll and carotenoid contents, but significantly increased root biomass. Compared to the low-accumulator HB, non-inoculated Cd-exposed SX plants had higher chlorophyll contents, and rhizobium-inoculated Cd-exposed SX plants had higher Pn, Tr, and Gs as well as higher levels of P, K, Fe, Ca, Zn, and Cu. In conclusion, the high- and low-Cd-accumulator exhibited different physiological responses to Cd exposure. Overall, rhizobium-inoculation of black locust promoted the growth and heavy metal absorption, providing an effective strategy for the phytoremediation of heavy metal-contaminated soils by this woody legume.

Roll-to-roll manufacturing of large surface area PDMS devices, and application to a microfluidic artificial lung.

The ability to cost-effectively produce large surface area microfluidic devices would bring many small-scale technologies such as microfluidic artificial lungs (μALs) from the realm of research to clinical and commercial applications. However, efforts to scale up these devices, such as by stacking multiple flat μALs have been labor intensive and resulted in bulky devices. Here, we report an automated manufacturing system, and a series of cylindrical multi-layer lungs manufactured with the system and tested for fluidic fidelity and function. A roll-to-roll (R2R) system to engrave multiple-layer devices was assembled. Unlike typical applications of R2R, the rolling process is synchronized to achieve consistent radial positioning. This allows the fluidics in the final device to be accessed without being unwrapped. To demonstrate the capabilities of the R2R manufacturing system, this method was used to manufacture multi-layer μALs. Gas and blood are engraved in alternating layers and routed orthogonally to each other. The proximity of gas and blood separated by gas permeable PDMS permits CO2 and O2 exchange via diffusion. After manufacturing, they were evaluated using water for pressure drop and CO2 gas exchange. The best performing device was tested with fresh whole bovine blood for O2 exchange. Three μALs were successfully manufactured and passed leak testing. The top performing device had 15 alternating blood and gas layers. It oxygenated blood from 70% saturation to 95% saturation at a blood flow of 3 mL min-1 and blood side pressure drop of 234 mmHg. This new roll-to-roll manufacturing system is suitable for the automated construction of multi-layer microfluidic devices that are difficult to manufacture by conventional means. With some upgrades and improvements, this technology should allow for the automatic creation of large surface area microfluidic devices that can be employed for various applications including large-scale membrane gas exchange such as clinical-scale microfluidic artificial lungs.

Photosynthesis governed by nanoparticulate titanium dioxide. The Pisum sativum L. case study

Wide availability of anthropogenic TiO2 nanoparticles facilitates their penetration into environment and prompts interactions with plants. They alter plants growth and change their nutritional status. In particular, metabolic processes are affected. In this work the effect of nanometric TiO2 on photosynthesis efficiency in green pea (Pisum sativum L.) was studied. Hydroponic cultivations with three Ti levels (10; 50 and 100 mg L−1) were applied. At all concentrations nanoparticles penetrated into plant tissues and were detected by the single particle ICP-MS/MS method. Nanoparticles altered the CO2 assimilation rate and gas exchange parameters (i.e. transpiration, stomatal conductance, sub-stomatal CO2 concentration). The most pronounced effects were observed for Ti 50 mg L−1 cultivation where photosynthesis efficiency, transpiration and stomatal conductance were increased by 14.69%, 4.58% and 8.92%, respectively. They were further confirmed by high maximum ribulose 1,5-bisphosphate carboxylation rate (27.40% increase), maximum electron transport rate (21.51% increase) and the lowest CO2 compensation point (45.19% decrease). Furthermore, concentrations of Cu, Mn, Zn, Fe, Mg, Ca, K and P were examined with the most pronounced changes observed for elements directly involved in photosynthesis (Cu, Zn, Mn, and Fe). The Cu concentrations in roots, stems and leaves for Ti 50 mg L−1 cultivation were below the control by 33.15%, 38.28% and 10.76%, respectively. The Zn content in analogous treatment and organs decreased by 30.24%, 26.69% and 13.35%. The Mn and Fe levels in leaves were increased by 72.22% and 50.32%, respectively. Our results indicated that plant defence mechanisms which restrain the water uptake have been overcome in pea by photocatalytic activity of nanoparticulate TiO2 which stimulated photosynthesis. On the contrary to the substantial stomatal conductance, the transpiration has been reduced because exceptional part of water flow was already consumed in chloroplasts and could not have been freed to the atmosphere.

Response of photosynthetic 13C discrimination to vapour pressure deficit reflects changes in bundle-sheath leakiness in two C4 grasses

Combined measurements of photosynthetic 13C discrimination (Δ) and gas exchange can be used to estimate bundle-sheath leakiness (Φ), a key efficiency parameter for the CO2-concentrating mechanism of C4 species and their intrinsic water-use efficiency (iWUE). Yet, how vapour pressure deficit (VPD) influences the CO2-concentrating mechanism and Φ in low-leakiness species has been rarely explored. Here, we performed on-line 13C discrimination, CO2 and H2O gas exchange measurements and dry matter δ13C analysis to study the responses of Δ, Φ, and iWUE to VPD in two graminaceous C4 species (guinea grass and pearl millet). Growth at high VPD led to an average increase of photosynthetic 13C discrimination (∆A) by 1.4‰ and a concurrent increase of Φ by 0.08 for both species. ∆ of leaf dry matter (∆DM) showed similar responses to VPD, but was consistently higher than ∆A by 0.4‰. The increase of ∆A was associated with increased leaf nitrogen content at high VPD. ∆A was positively correlated with iWUE and leaf nitrogen content but was unrelated with specific leaf area. This study demonstrated that Φ is variable at different growth VPD, an effect that should be taken into account when using ∆ to estimate iWUE in C4 species.

Seasonal changes in gas exchange, water and macro-nutrient content differ between Citrus cultivars

Citrus is an evergreen broad-leaved fruit tree including numerous species and cultivars with an extensive global planting area. However, the relationship between physiological parameters and seasonal fruit ripening of different citrus cultivars has not been reported. With the aim to obtain information on this relationship, we selected two late-maturing (Newhall Navel and Ponkan) and two middle-maturing citrus cultivars (Fertile orange and Tarocco) and compared the seasonal patterns of foliar CO2 and H2O gas exchange, leaf water content and macro-nutrient concentrations in leaves and roots. Our results showed that seasonal changes of foliar CO2 and H2O gas exchange and water content greatly differed between cultivars at defined developmental stages, but especially during fruit ripening. For example, in December, the net rates of photosynthetic CO2 fixation (Pn) of the late-maturing cultivars were significantly higher than in middle-maturing cultivars. Seasonal fluctuations of total nitrogen (N), total phosphorus (P), and inorganic phosphorus (Pi), as well as C/N, C/P, and N/P ratios in leaves and roots differed between middle and late-maturing cultivars. These differences were most obvious at fruit ripening compared to other developmental stages and were significantly higher in leaves than in roots. We conclude that seasonal differences in foliar Pn and macro-nutrient contents between leaves of citrus cultivars are largely determined by seasonal fruit ripening. In addition, seasonal changes in root macro-nutrient contents were also affected by seasonal fruit ripening of citrus cultivars. However, this effect was much lower compared to the leaves, but still indicates particular shoot-root interactions during fruit ripening.

CO<sub>2</sub> Exchange Of Seedlings Of <i>Rhizophora Apiculata Bl.</i> In Artificial And Natural Mangrove Forests Of Southern Vietnam

Mangrove forests are an important part of tropical coastal ecosystems. Until recently, these forests were intensively exterminated. Currently, the issue of mangrove conservation is being discussed at a number of symposiums due to their significant role in reducing the effects of greenhouse gas emissions. However, there has recently been uncertainty in estimation of CO2 fluxes in mangrove forests due to a lack of field research. The results of studies of photosynthesis at the leaf level in-situ in seedlings of Rhizophora apiculata Blume, 1827 of both natural and artificial origin are presented. The studies were carried out on a mangrove plantation growing in Can Gio Mangrove Biosphere Reserve, which is 50 kilometres from Ho Chi Minh City (South Vietnam). CO2 gas exchange during photosynthesis was measured using a gas analysing system called the LI-6800 (USA). Photosynthetically active radiation (PAR) is the main factor affecting the photosynthesis of the studied seedlings. Artificial seedlings that were grown in open areas had higher productivity and greater photosynthetic rates. It has been determined that the measured photosynthesis are scattered over three clearly marked zones, which correspond to the measurements of photosynthesis made in the pre-noon, noon and afternoon hours. The water reserves used up before noon were not fully replenished in the afternoon by the seedlings. Based on the results obtained, it has been suggested that the main inhibitory factor affecting the photosynthesis of R. apiculata (if PAR is not taken into account) is a violation of the water balance of the leaves.The optimum air temperature for photosynthesis processes in seedlings is (35 ± 2) °C. The intensity of photosynthesis also increases with an increase in the concentration of CO2 in the air. The increases of photosynthesis continue until the concentration of CO2 reaches ~1000 µmol·mol-1 and then do not increase. We associate this circumstance with the maximum possibilities of the photosynthetic apparatus of the leaf of the studied plant. The obtained research results will contribute to a better theoretical understanding of the productivity of plants of this species in the respective ecosystems, and will also allow us to move from photosynthesis at the leaf level to photosynthesis at the planting level. The work’s mathematical models can be used to model changes in R. apiculata photosynthesis from the point of view of climate change.

Effect of antigibberellins on morphogenesis, photosynthetic apparatus, productivity and their residual content in tomato fruits

The application of growth and development regulators on crops in order to optimize their production process is one of the leading tasks of modern plant physiology. Retardants – gibberellin inhibitors are widely used for this purpose. We investigated the effect of foliar treatment with EW-250, ССС-750 and 2-СEPA on morphogenesis, leaf apparatus, content of photosynthetic pigments, indices of chlorophyll fluorescence induction, CO2 gas exchange, and residual amounts of drugs in the fruits of tomato (Lycopersicon esculentum Mill.) Bobcat hybrid. The field experiment was laid on plots with an area of 33 m2. The treatment of the plants was carried out at the budding stage. Morphometric indices were determined at the stages of flowering and fruit formation. The chlorophylls content was determined in the raw material by the spectrophotometric method. Indices of photosystem II (PSII) photochemical activity were determined according to the parameters of chlorophyll fluorescence induction after a half-hour exposure of plants in the dark using a portable single-beam fluorimeter "Floratest". The determination of the residual content of retardants in the fruits was carried out on a Shimadzu GC gas chromatograph with a mass spectrometric detector – GCMS- QP2020 EI. All gibberellin inhibitors reduced linear plant size. The number of leaves on the plants decreased under 2-CEPA treatment, and increased after the application of EW-250. Treatment with 2-CEPA decreased, EW-250 significantly increased, and CCC-750 practically did not change the leaves’ fresh and dry weight. Leaf area and leaf index decreased under 2-CEPA treatment, but practically did not change when EW-250 and ССС-750 were applied. All antigibberellin drugs increased the leaf specific leaf weight and thickened the leaf lamina due to the growth of chlorenchyma cells. At the same time, growth inhibitors increased the volume of columnar parenchyma cells and practically did not change the size of spongy parenchyma cells. Retardants increased the chlorophylls content in leaves, while the ethylene producer 2-CEPA did not change this index. The plants’ chlorophyll index after treatment with drugs increased significantly. The whole plant dry weight increased under EW-250 treatment, decreased after 2-CEPA application, and did not change under CCC-750. It was established that the photosynthetic rate increased under the EW-250 treatment, both in the flowering stage and in the stage of fruit formation, while when using 2-CEPA and CCC-750, it occurred only at the stage of fruit formation. The most significant positive changes of PSII photochemical activity indices were observed under the use of EW-250. Under the action of the drug, the maximum and actual quantum efficiency of PSII increased, the linear electron transport accelerated, and the fraction of reaction centers that did not transfer electrons from the primary acceptor QA to QB decreased, at the same time the chlorophyll fluorescence decay coefficient significantly increased, which indicates an increase in the CO2 assimilation intensity. Retardants increased the proportion of the fruit in the whole plant dry weight. All growth regulators increased net photosynthetic efficiency. A significant increase in fruit yield occurred under EW-250 treatment. When using CCC-750, the index tended to increase, while under the influence of 2-CEPA the yield decreased. The residual amounts of EW-250 and CCC-750 in the fruits did not exceed the maximum permissible concentrations.

Mechanisms Underlying the C3–CAM Photosynthetic Shift in Facultative CAM Plants

Crassulacean acid metabolism (CAM), one of three kinds of photosynthesis, is a water-use efficient adaptation to an arid environment. CAM is characterized by CO2 uptake via open stomata during the nighttime and refixation CO2 via the Calvin cycle during the daytime. Facultative CAM plants can shift the photosynthesis from C3 to CAM and exhibit greater plasticity in CAM expression under different environments. Though leaf thickness is an important anatomical feature of CAM plants, there may be no anatomical feature changes during the C3–CAM transition for all facultative CAM plants. The shift from C3 photosynthesis to CAM in facultative CAM plants is accompanied by significant changes in physiology including stomata opening, CO2 gas exchange and organic acid fluxes; the activities of many decarboxylating enzymes increase during the shift from C3 to CAM; the molecular changes occur during the photosynthesis C3–CAM shift involved DNA hypermethylation, transcriptional regulation, post-transcriptional regulation and protein level regulation. Recently, omics approaches were used to discover more proceedings underling the C3–CAM transition. However, there are few reviews on the mechanisms involved in this photosynthetic shift in facultative CAM plants. In this paper, we summarize the progress in the comparative analysis of anatomical, physiological, metabolic and molecular properties of facultative CAM plants between C3 and CAM photosynthesis. Facultative CAM plants also show the potential for sustainable food crop and biomass production. We also discuss the implications of the photosynthesis transition from C3 to CAM on horticultural crops and address future directions for research.

Influence of lactation stage on heat production and macronutrient oxidation in dairy cows during a 24-hour fasting period

Understanding nutrient utilization and partitioning is essential for advancing the efficiency of dairy cattle. Our objective was to determine if dairy cows exposed to a 24-h fasting period differ in heat production (HP) and macronutrient oxidation at different stages of lactation. Twelve primiparous, lactating German Holstein dairy cows were used in a longitudinal study design spanning from 2013 to 2014. Dairy cows were housed in respiration chambers during 3 stages of the lactation cycle: early (mean ± SD; 28.8 ± 6.42 d), mid- (89.4 ± 4.52 d), and late (293 ± 7.76 d) lactation. Individual CO2, O2, and CH4 gas exchanges were measured every 6 min for two 24-h periods, an ad libitum period and fasting period (RES). Blood was sampled at the start and end of the RES period. Gas measurements were used to calculate HP, net carbohydrate oxidation (COX), and net fat oxidation (FOX). Measurements were corrected with metabolic BW (kg of BW0.75; cBW). The RES period for each stage of lactation was further subdivided into the start (RESstart) and end (RESend) by averaging the first and last 2 h of the RES period. The net change was calculated as RESend - RESstart. All energy variables differed among lactation stage within the RES period except for HP/cBW. As expected, COX, COX/cBW, COX/HP, HP, and HP/cBW, were greater at the RESstart compared with RESend, whereas FOX, FOX/cBW, and FOX/HP were greater at the RESend except for FOX and FOX/cBW during mid lactation, which was only a tendency for a difference. The net change for COX, COX/cBW, HP, HP/cBW, and FOX/cBW did not differ among stages of lactation. Despite detecting a tendency for a difference among stage of lactation for FOX, pairwise analysis revealed no differences. Plasma triglyceride, urea, and nonesterified fatty acid concentrations were greater at RESend than RESstart. The net change for plasma glucose, urea, β-hydroxybutyrate, and nonesterified fatty acid concentrations were greater in early than late lactation. Our results demonstrate that despite differences in absolute measurements of energy variables and plasma metabolites, the change in whole-body macronutrient oxidation and HP as cows' transition from a fed-like state to a starvation-like state during a 24-h fasting period is consistent throughout lactation.

The Effect of Short-Term Heating on Photosynthetic Activity, Pigment Content, and Pro-/Antioxidant Balance of A. thaliana Phytochrome Mutants.

The effects of heating (40 °C, 1 and 2 h) in dark and light conditions on the photosynthetic activity (photosynthesis rate and photosystem II activity), content of photosynthetic pigments, activity of antioxidant enzymes, content of thiobarbituric acid reactive substances (TBARs), and expression of a number of key genes of antioxidant enzymes and photosynthetic proteins were studied. It was shown that, in darkness, heating reduced CO2 gas exchange, photosystem II activity, and the content of photosynthetic pigments to a greater extent in the phyB mutant than in the wild type (WT). The content of TBARs increased only in the phyB mutant, which is apparently associated with a sharp increase in the total peroxidase activity in WT and its decrease in the phyB mutant, which is consistent with a noticeable decrease in photosynthetic activity and the content of photosynthetic pigments in the mutant. No differences were indicated in all heated samples under light. It is assumed that the resistance of the photosynthetic apparatus to a short-term elevated temperature depends on the content of PHYB active form and is probably determined by the effect of phytochrome on the content of low-molecular weight antioxidants and the activity of antioxidant enzymes.

The Impact of Chitosan at the Physical Performance of the Coffee Skin-Based Edible Film

offee is one of the most popular commodities in decades. The expansion of coffee plantations and processing indirectly increases the number of coffee skins. Coffee skin is a problem for the community because it can pollute the environment, and cause an unpleasant odor and an unsightly view. Processing coffee skins into edible films will help overcome the problem of coffee skin waste. Chitosan can be added to increase the functional value of coffee peel-based edible films. Chitosan can form layers, does not affect taste, or aroma, and is safe for consumption. Chitosan also contains a variety of antimicrobial bioactive compounds and can act as a selectively permeable membrane for CO2 and O2 gas exchange. The purpose of this observation turned out to be to determine the impact of the quantity of coffee skins and the concentration of chitosan on the physical properties of edible films made from coffee skins. The study design used a randomized block of two factors, namely the concentration of chitosan (1.0 and 1.5%) and the number of coffee skins (7, 14, 21, and 28%). Each treatment was repeated three times, to determine the physical properties of the coffee skin edible film, namely color (ΔE), transparency, film performance, structural density, thickness, and acidity. The results showed that the number of coffee skins and the concentration of chitosan affected the physical characteristics of edible films made from coffee skins. A concentration of 1.5% chitosan with 21% coffee skin produced the best edible film. How to Cite: Luh Suriati, I. Gede Pasek Mangku, Gek Ayu Sagita Widya Krisnawati, Anak Agung Ngurah Surya Girindra, 2022. "The Impact of Chitosan at the Physical Performance of the Coffee Skin-Based Edible Film." Journal of Agriculture and Crops, vol. 9, pp. 156-163.

The effects of growth regulators on the photosynthetic apparatus of the sweet pepper (Capsicum annuum L.) in relation to the productivity

The effects of growth stimulants 6-benzylaminopurine (6-BAP), gibberellic acid (GA3) and 1-naphthaleneacetic acid (1-NAA) as well as gibberellin inhibitors tebuconazole (EW-250), ethephon (2-chloroethylphosphonic acid, 2-CEPA) and chloromequate chloride (ССС-750), which differ in their action mechanism, on growth, development, leaf apparatus formation, CO2 and H2O gas exchange, photochemical activity of Photosystem II (PSII) and productivity traits of sweet pepper plants were studied. It was shown that treatment with growth stimulants increased, and gibberellin inhibitors decreased the linear sizes of sweet pepper plants of the Antei variety. It was established that all growth regulators, except for 2-CEPA, increased the number and the mass of leaves on the plant. Under the action of all preparations, except for 2-CEPA, the area of the leaves increased. Gibberellin inhibitors and 6-BAP significantly increased the amount of chlorophyll in pepper leaves. However, it decreased under the action of GA3 and did not practically change in treatment with 1-NAA. All growth substances, except GA3, increased the total chlorophyll content in the plant. The impact of growth regulators on the activity of photosynthetic processes was more pronounced at the stage of fruit formation than at the flowering stage. The CO2 assimilation rate at the flowering stage increased under the treatment of 1-NAA, 6-BAP, 2-CEPA and EW-250, but decreased under the action of GA3 and CCC-750. At the same time, all studied growth regulators increased the CO2 assimilation rate at the stage of fruit formation. Changes in the CO2 assimilation rate were closely correlated with changes in stomatal conductance (r = 0.79—0.85). Growth regulators increased transpiration in the light at fruit formation stage while the transpiration in the dark was reduced at the flowering stage. Growth regulators increased the operating quantum efficiency of PSII in the light, photochemical quenching of chlorophyll fluorescence, and intensity of linear electron transport in chloroplasts, and reduced non-photochemical quenching (NPQ) fluorescence. The specified morphological, physiological and biochemical changes in plants of sweet pepper of the Antei variety contributed to improvement of crop productivity traits. The use of growth stimulants 6-BAP and GA3, and retardants EW-250 and ССС-750 was most effective.

Research of the growth and development of woody plants in radon-active territories of Karelia

The influence of lithospheric gases on the growth and development of plants is studied. Using a number of areas in Karelia as an example, the weak (300-700 Bq/m3) and strong (6000-8000 Bq/m3) effects of radon on woody plants were analyzed. In areas with high radon activity, an increased frequency of structural anomalies of plant trunks, tumor-like growths, bark necrosis, cancerous diseases of fungal origin, and loss of immunity in plants at a young age are noted. Resistant species in such zones are alder and juniper. In zones of moderate radon activity, carbon dioxide fluxes from the soil surface and at different depths were measured, and the processes of growth and CO2 gas exchange of Scots pine shoots were studied. It has been shown that a CO2 flow of deep origin can increase pine growth by 15-20%.