Gas Exchange Dynamics Research Articles

A novel method for determining ventilatory and gas exchange dynamics during exercise: the "chirp" waveform.

Quantitating exercise ventilatory and gas exchange dynamics affords insights into physiological control processes and cardiopulmonary dysfunction. We designed a novel waveform, the chirp waveform, to efficiently extract moderate-intensity exercise response dynamics. In the chirp waveform, work rate fluctuates sinusoidally with constant amplitude as sinusoidal period decreases progressively from ∼8.5 to 1.4 min over 30 min of cycle ergometry. We hypothesized that response dynamics of pulmonary ventilation (V̇e) and gas exchange [oxygen uptake (V̇o2) and carbon dioxide output (V̇co2)] extracted from chirp waveform are similar to those obtained from stepwise transitions. Thirty-one participants [14 young healthy, 7 older healthy, and 10 patients with chronic obstructive pulmonary disease (COPD)] exercised on three occasions. Participants first performed ramp-incremental exercise for gas exchange threshold (GET) determination. In randomized order, the next two visits involved either chirp or stepwise waveforms. Work rate amplitude (20 W to ∼95% GET work rate) and exercise duration (30 min) were the same for both waveforms. A first-order linear transfer function with a single system gain (G) and time constant (τ) characterized response dynamics. Agreement between model parameters extracted from chirp and stepwise waveforms was established using Bland-Altman analysis and Rothery's concordance coefficient (RCC). V̇e, V̇o2, and V̇co2 Gs showed no systematic bias (P > 0.178) and moderate-to-good agreement (RCC > 0.772, P < 0.01) between waveforms. Similarly, no systematic bias (P = 0.815) and good agreement (RCC = 0.837, P < 0.001) was found for τV̇o2. Despite moderate agreement for τV̇co2 (RCC = 0.794, P < 0.001) and τV̇e (RCC = 0.722, P = 0.083), chirp τ was less [-6.9(11.7) s and -12.2(22.5) s, respectively]. We conclude that the chirp waveform is a promising method for measuring exercise response dynamics and investigating physiological control mechanisms.NEW & NOTEWORTHY We investigated the ability of a novel waveform to extract exercise ventilatory and gas exchange dynamics. In the chirp waveform, work rate fluctuates sinusoidally with constant amplitude as sinusoidal period decreases progressively over 30 min of exercise. In a study of 31 healthy individuals and patients with COPD, comparison of exercise dynamics derived from chirp to those from stepwise waveforms suggests that the chirp waveform is a promising method for derivation of exercise response dynamics.

Dynamics of gas exchange and heart rate signal entropy in standard cardiopulmonary exercise testing during critical periods of growth and development.

Standard cardiopulmonary exercise testing (CPET) produces a rich dataset but its current analysis is often limited to a few derived variables such as maximal or peak oxygen uptake (V̇O2). We tested whether breath-by-breath CPET data could be used to determine sample entropy (SampEn) in 81 healthy children and adolescents (age 7-18 years old, equal sex distribution). To overcome challenges of the relatively small time-series CPET data size and its nonstationarity, we developed a Python algorithm for short-duration physiological signals. Comparing pre- and post-ventilatory threshold (VT1) CPET phases, we found: (1) SampEn decreased by 9.46% for V̇O2 and 5.01% for V̇CO2 (p < 0.05), in the younger, early-pubertal participants; and (2) HR SampEn fell substantially by 70.8% in the younger and 77.5% in the older participants (p < 0.001). Across all ages, females exhibited greater HR SampEn than males during both pre- and post VT1 CPET phases by 14.10% and 23.79%, respectively, p < 0.01. In females, late-pubertal had 17.6% lower HR SampEn compared to early-pubertal participants (p < 0.05). Breath-by-breath gas exchange and HR data from CPET are amenable to SampEn analysis that leads to novel insight into physiological responses to work intensity, and sex and maturational effects.

The UCI Fluxtron: A versatile dynamic chamber and software system for biosphere–atmosphere exchange research

Here we present the UCI Fluxtron, a cost-effective multi-enclosure dynamic gas exchange system that provides an adequate level of control of the experimental conditions for investigating biosphere–atmosphere exchange of trace gases.We focus on the hardware and software used to monitor, control, and record the air flows, temperatures, and valve switching, and on the software that processes the collected data to calculate the exchange flux of trace gases.We provide the detailed list of commercial materials used and also the software code developed for the Fluxtron, so that similar dynamic enclosure systems can be quickly adopted by interested researchers. Furthermore, the two software components –Fluxtron Control and Fluxtron Process– work independently of each other, thus being highly adaptable for other experimental designs.Beyond plants, the same experimental setup can be applied to the study of trace gas exchange by animals, microbes, soil, or any materials that can be enclosed in a suitable container.

Biochemical versus stomatal acclimation of dynamic photosynthetic gas exchange to elevated CO2 in three horticultural species with contrasting stomatal morphology.

Understanding photosynthetic acclimation to elevated CO2 (eCO2) is important for predicting plant physiology and optimizing management decisions under global climate change, but is underexplored in important horticultural crops. We grew three crops differing in stomatal density-namely chrysanthemum, tomato, and cucumber-at near-ambient CO2 (450 μmol mol-1) and eCO2 (900 μmol mol-1) for 6 weeks. Steady-state and dynamic photosynthetic and stomatal conductance (gs) responses were quantified by gas exchange measurements. Opening and closure of individual stomata were imaged in situ, using a novel custom-made microscope. The three crop species acclimated to eCO2 with very different strategies: Cucumber (with the highest stomatal density) acclimated to eCO2 mostly via dynamic gs responses, whereas chrysanthemum (with the lowest stomatal density) acclimated to eCO2 mostly via photosynthetic biochemistry. Tomato exhibited acclimation in both photosynthesis and gs kinetics. eCO2 acclimation in individual stomatal pore movement increased rates of pore aperture changes in chrysanthemum, but such acclimation responses resulted in no changes in gs responses. Although eCO2 acclimation occurred in all three crops, photosynthesis under fluctuating irradiance was hardly affected. Our study stresses the importance of quantifying eCO2 acclimatory responses at different integration levels to understand photosynthetic performance under future eCO2 environments.

Impact of canopy environmental variables on the diurnal dynamics of water and carbon dioxide exchange at leaf and canopy level

Abstract. Quantifying water vapor and carbon dioxide (CO2) exchange dynamics between the land and the atmosphere through observations and modeling is necessary in order to reproduce and project near-surface climate in coupled land–atmosphere models. The exchange of water and CO2 occurs at the leaf surface (leaf level) and in a net manner through exchanges at all the leaf surfaces composing the vegetation canopy and at the soil surface (canopy level). These exchanges depend on the meteorological forcings imposed by the overlying atmosphere (atmospheric boundary layer level). In this paper, we investigate the effect of four canopy environmental variables (photosynthetic active radiation (PAR), water vapor pressure deficit (VPD), air temperature (T), and atmospheric CO2 concentration (Ca)) on the local individual leaf exchange and canopy exchange of water and CO2 at hourly timescales. Additionally, we investigate the effect of atmospheric boundary layer (ABL) processes on the local exchange. To that end, we simultaneously investigated the exchanges of water and CO2 at leaf level and canopy level for an alfalfa field in northern Spain over 1 day in summer 2021. We used comprehensive observations ranging from stomatal conductance to ABL measurements collected during the Land Surface Interactions with the Atmosphere in the Iberian Semi-Arid Environment (LIAISE) experiment. To support the observational analysis, we used a coupled land–atmosphere model (CLASS model) that has representations at all levels considered. To relate how temporal changes of the four environmental variables modify the fluxes of water and CO2, we studied tendency equations of the leaf gas exchange. These mathematical expressions quantify the temporal evolution of the leaf gas exchange as a function of the temporal evolution of PAR, VPD, T, and Ca. To investigate the effects of ABL processes on the local exchange, we developed three modeling experiments that impose surface radiative perturbations by a cloud passage (which perturbed PAR, T, and VPD), entrainment of dry air from the free troposphere (which perturbed VPD), and advection of cold air (which perturbed T and VPD). The model results and observations matched the leaf gas exchange (r2 between 0.23 and 0.67) and canopy gas exchange (r2 between 0.90 and 0.95). The tendency equations of the modeled leaf gas exchange during the study day revealed that the temporal dynamics of PAR were the main contributor to the temporal dynamics of the leaf gas exchange, with atmospheric CO2 temporal dynamics being the least important contributor. From the three modeling experiments with ABL perturbations, the surface radiative changes induced by a cloud perturbed the CO2 exchange the most, whereas all of them perturbed the water exchange to a similar extent. Second-order effects on the dynamics of the leaf gas exchange were also identified using the tendency equations. For instance, the decrease in the net CO2 assimilation rate during the cloud passage caused by a decrease in surface radiation was further enhanced due to the decrease in air temperature also associated with the cloud. With this research we showcase that the proposed tendency equations can disentangle the effect of environmental variables on the leaf exchange of water and CO2 with the atmosphere, as represented in land–surface parameterization schemes. As such, this framework can become a useful tool with which to analyze these schemes in weather and climate models.

Phenology, gas exchange, biomass accumulation, and irrigated rice yield under alternative irrigation managements

AbstractIn Brazil, rice production is predominantly concentrated in the South region, employing a continuous flood irrigation system throughout the crop cycle. However, this irrigation management strategy in the tropical region contributes to low water‐use efficiency owing to adverse climatic conditions. Furthermore, with climate change projections indicating reduced water availability, the study aims to investigate the impact of alternative irrigation management strategies on the phenological development, gas exchange, biomass accumulation, and productivity of tropical irrigated rice. Three alternative irrigation management approaches—intermittent flood irrigation with aeration (IFA), intermittent flood irrigation throughout the growth cycle (IFC), and intermittent flooding up to the flowering stage (IFF)—were compared with the traditional continuous flood irrigation throughout the growth cycle. Phenological data, gas exchange, growth, and productivity dynamics were subject to analysis, providing overarching insights into management practices. Notably, irrigation management exhibited no influence on the vegetative phase of the crop. The implementation of intermittent flood irrigation facilitated a reduction in water supply without compromising the physiological performance of tropical irrigated rice. Strategies promoting judicious water utilization, such as IFA and IFC, can be readily integrated into the cultivation of tropical irrigated rice without detriment to grain yield or harvest index.

(Invited) Atomic Layer Deposition as the Enabler for the Meta Stable Semiconductor InN and Its Alloys

Indium nitride (InN) is highly interesting for high-frequency and high-speed electronics given the remarkably high electron mobility in InN. The development of InN based electronics is hampered by the difficulty in depositing high quality thin films. The InN crystal breaks down to indium metal and nitrogen gas at about 500 °C which limits the deposition temperature, making conventional chemical vapor deposition (CVD) poorly suited for InN. Atomic Layer Deposition (ALD) is a low temperature, time-resolved form of CVD where the precursor gases are pulsed sequentially, separated by inert gas. This renders a deposition chemistry fully controlled by surface chemistry. We hypothesized around 2015 that the surface-controlled deposition of ALD will be beneficial for InN deposition and started our activities on ALD of InN.I will describe our work on ALD of InN films where we have focused on ALD process development and design of new precursors. We now can show that ALD is an enabling technology for InN based electronics as it is capable of depositing a few nanometers continuous, epitaxial InN films.[1] I will describe our results on epitaxial growth of InN by ALD using our newly invented In precursor [2] and describe why we believe that the key to the success of ALD for InN is the dynamic gas exchange during the deposition.[3] I will also show our atomic scale understanding of the growth chemistry from quantum chemical modelling,[4] and how the results can be extended to InxGa1-xN.[5, 6]

Stomatal closure in maize is mediated by subsidiary cells and the PAN2 receptor.

Stomata are epidermal pores that facilitate plant gas exchange. Grasses have fast stomatal movements, likely due to their dumbbell-shaped guard cells and lateral subsidiary cells. Subsidiary cells reciprocally exchange water and ions with guard cells. However, the relative contribution of subsidiary cells during stomatal closure is unresolved. We compared stomatal gas exchange and stomatal aperture dynamics in wild-type and pan1, pan2, and pan1;pan2 Zea mays (L.) (maize) mutants, which have varying percentages of aberrantly formed subsidiary cells. Stomata with 1 or 2 defective subsidiary cells cannot close properly, indicating that subsidiary cells are essential for stomatal function. Even though the percentage of aberrant stomata is similar in pan1 and pan2, pan2 showed a more severe defect in stomatal closure. In pan1, only stomata with abnormal subsidiary cells fail to close normally. In pan2, all stomata have stomatal closure defects, indicating that PAN2 has an additional role in stomatal closure. Maize Pan2 is orthologous to Arabidopsis GUARD CELL HYDROGEN PEROXIDE-RESISANT1 (GHR1), which is also required for stomatal closure. PAN2 acts downstream of Ca2+ in maize to promote stomatal closure. This is in contrast to GHR1, which acts upstream of Ca2+ , and suggests the pathways could be differently wired.

Technical note: Skirt chamber – an open dynamic method for the rapid and minimally intrusive measurement of greenhouse gas emissions from peatlands

Abstract. We present a reliable and robust open dynamic chamber for measuring greenhouse gas exchange in peatlands with minimal disturbance of the ground. This chamber, called the “skirt chamber”, is based on a transparent plastic film placed above an open frame made of sparse interwoven wires and expanded around the base of the chamber below a steel chain that ensures contact to the ground, avoiding damage, trenching, and cutting vegetation. Gas exchange is determined using a portable gas analyzer from a mass balance in which the imperfect sealing of the chamber to the ground is quantified through the injection of a methane pulse. The method was tested on a pristine peatland dominated by Sphagnum magellanicum located on Navarino Island in the subantarctic Magellanic ecoregion in Chile. Our results indicate that the skirt chamber allowed the determination of methane fluxes and ecosystem respiration in about 20 min, with a limit of detection of 0.185 mg CH4 m−2 h−1 and 173 mg CO2 m−2 h−1, respectively. We conclude that the skirt chamber is a minimally intrusive, fast, portable, and inexpensive method that allows the quantification of greenhouse gas emissions with high spatial resolution in remote locations and without delay.

Functional adjustment under lethal drought and physiological memory to water stress of two phylogenetically close and coexisting conifers

Forest die-off can primarily affect the least drought-tolerant species and mortality be modulated by physiological legacies left by drought. To characterize the functional response and physiological memory to water stress of two phylogenetically and functionally close conifers with current contrasting field mortality and regeneration dynamics, we conducted a drought experiment in which seedlings were driven to death. Both species exhibited isohydric behavior with small hydroscapes. Yet, hydraulic performance, osmotic adjustment and gas exchange dynamics under rising water stress consistently showed that Pinus pinea was more resistant to drought than Pinus pinaster. Under water stress, P. pinaster exhibited greater water use efficiency, but higher photochemical damage and more constrained photosynthetic and stomatal conductance dynamics than P. pinea. Xylem conductivity loss under water stress and the wilting point were lower in P. pinea. Osmotic potential at full turgor decreased in P. pinea but it increased in P. pinaster with increasing water stress below a water potential threshold. Consequently, lethal water stress levels were higher for P. pinea than for P. pinaster. Synergistically, cumulative water stress induced physiological legacies curtailing carbon uptake and hydraulic performance in both species. Negative physiological legacies left by memory to water stress in plants, might explain delayed tree mortality years after drought. The functional responses to drought characterized agree with current field demographic dynamics under climate change in mixed evergreen forests where more drought-tolerant taxa like P. pinea are replacing formerly dominated P. pinaster stands.

An effective strategy to boost hydrogen separation performance through stable mixed proton‐electron conducting membrane

AbstractHydrogen separation and purification are key to widespread application of hydrogen energy. Hydrogen permeable membranes based on lanthanum tungstate (LWO) attract attention due to favorable mechanical strength and chemical stability. However, industrial application of LWO‐based membranes has remained challenging because of modest hydrogen permeances. Here we report a novel graded porous supported symmetric (GPSS) LWO‐based membrane with improved transport properties, gas exchange dynamics, and operational stability, boosting stable hydrogen flux by several times over previously reported state‐of‐the‐art membranes.

Coupling dynamics of respiration, gas exchange, and Pseudomonas fluorescens growth on fresh-cut cucumber (Cucumis sativus L.) in passive modified atmosphere packing

This study established microbial growth models for fresh-cut cucumber packaged with different O2 transmission rate (OTR) films. Biaxially oriented polyamide/low-density polyethylene (BOPA/LDPE) film (Ⅰ: OTR5, Ⅳ: OTR48) and polyethylene (PE) film (Ⅱ: OTR2058, Ⅲ: OTR3875) were used to construct a passive modified atmosphere packaging (MAP). Mathematic models have been established to account for dynamic variations in the O2/CO2 concentration and their impacts on Pseudomonas fluorescens growth. The coupling models included: 1) respiration models of cucumber and P. fluorescens based on Michaëlis-Menten equation, 2) coupling gas exchange models based on Fick’s law that contained models of P. fluorescens growth and respiration, 3) coupling microbial growth models contained respiration and gas exchange models. Coupling model with Baranyi function successfully fitted variations of O2/CO2 concentration and P. fluorescens growth in the two packaging. In addition, quality properties of packed fresh-cut cucumber were determined. The film Ⅳ (OTR48) as a high barrier film showed the highest inhibition of P. fluorescens growth, adequately retained its colour, firmness and total soluble solid (TSS) concentration in contrast to the PE films packaging. The constructed coupling models can be utilized for assessing the shelf life and microbial growth of fresh-cut vegetables with spoilage dominated by pseudomonads.

Temporal variation in nitrous oxide (N2O) fluxes from an oil palm plantation in Indonesia: An ecosystem‐scale analysis

AbstractThe rapidly growing areal extent of oil palm (Elaeis guineensis Jacq.) plantations and their high fertilizer input raises concerns about their role as substantial N2O sources. In this study, we present the first eddy covariance (EC) measurements of ecosystem‐scale N2O fluxes in an oil palm plantation and combine them with vented soil chamber measurements of point‐scale soil N2O fluxes. Based on EC measurements during the period August 2017 to April 2019, the studied oil palm plantation in the tropical lowlands of Jambi Province (Sumatra, Indonesia) is a high source of N2O, with average emission of 0.32 ± 0.003 g N2O‐N m−2 year−1 (149.85 ± 1.40 g CO2‐equivalent m−2 year−1). Compared to the EC‐based N2O flux, average chamber‐based soil N2O fluxes (0.16 ± 0.047 g N2O‐N m−2 year−1, 74.93 ± 23.41 g CO2‐equivalent m−2 year−1) are significantly (~49%, p &lt; 0.05) lower, suggesting that important N2O pathways are not covered by the chamber measurements. Conventional chamber‐based N2O emission estimates from oil palm up‐scaled to ecosystem level might therefore be substantially underestimated. We show that the dynamic gas exchange of the oil palm canopy with the atmosphere and the oil palms' response to meteorological and soil conditions may play an important but yet widely unexplored role in the N2O budget of oil palm plantations. Diel pattern of N2O fluxes showed strong causal relationships with photosynthesis‐related variables, i.e. latent heat flux, incoming photosynthetically active radiation and gross primary productivity during day time, and ecosystem respiration and soil temperature during night time. At longer time scales (&gt;2 days), soil temperature and water‐filled pore space gained importance on N2O flux variation. These results suggest a plant‐mediated N2O transport, providing important input for modelling approaches and strategies to mitigate the negative impact of N2O emissions from oil palm cultivation through appropriate site selection and management.

Influence of Environmental Conditions on Carbon and Water Exchange Processes in Aucuba japonica Thunb.

In the context of climate change and deterioration of environmental conditions in urbanized regions, the study of the ecophysiological features of woody plants in order to select them for effective landscaping is of particular relevance. In this paper, the influence of abiotic factors on the daily variability of CO2/H2O gas exchange of Aucuba japonica Thunb., 1783 during the growing season on the Southern Coast of the Crimea is investigated. A photosynthesis monitor RTM-48A and a phytomonitor PM-11z (Bio Instruments S.R.L., Moldova) were used to measure gas exchange and environmental parameters. The analysis of the seasonal dynamics of carbon dioxide gas exchange showed a high sensitivity of the processes of carbon and water exchange of A. japonica to the prevailing environmental conditions, which cause fluctuations in the value of the daily carbon dioxide absorption more than four times. The preservation of the positive carbon balance of A. japonica under hydrothermal stress indicates the significant potential of plants for optimizing the urban ecosystems of the southern regions of Russia. Based on the revealed relationships a nonlinear regression equation is constructed, which can be used to predict the assimilation activity of A. japonica under current environmental conditions and expected climate changes.

Temperature Dynamics of Growth, CO&lt;sub&gt;2&lt;/sub&gt; Gas Exchange and Competitiveness of &lt;i&gt;Daedaleopsis confragosa&lt;/i&gt; and &lt;i&gt;D. tricolor&lt;/i&gt;

The temperature dynamics of mycelium growth, СО2 gas exchange and competitiveness of Daedaleopsis confragosa and D. tricolor were analyzed. It has been shown that on agar (MEA) mycelium growth is limited to 5–35°C, and its maximum is observed at 30°C (D. confragosa) – 35°C (D. tricolor). The mycelium СО2 gas exchange at MEA is recorded in the range of 5–50°C, with a maximum for D. confragosa at 35°C and 45°C for D. tricolor. The temperature dynamics of CO2 gas exchange in wood destroyed by D. confragosa and D. tricolor does not fundamentally differ from that of dikaryotic mycelium on MEA: recorded in the same temperature range (5–50°C), the temperature maximum is higher in D. tricolor (40)°C than in D. confragosa (30°C). According to the temperature characteristics of mycelium growth and СО2 gas exchange D. confragosa and D. tricolor can be characterized as mesophilic fungi, but differ in pronounced ecological individuality in relation to low and high temperatures. D. confragosa is characterized by more intensive growth and СО2 gas exchange of mycelium at 5–10°C, and D. tricolor at 35–50°C, which determines the temperature dynamics of their competitiveness: higher in D. confragosa at low, and in D. tricolor – at high temperatures. This corresponds to their geographical distribution: the first one is found in all latitudinal parts of the forest zone, and the second one is absent in its northern part, but common in the southern. According to the geographical and ecological-physiological features, D. tricolor can apparently be considered as the southern subspecies of D. confragosa s.l.

Modeling the Impact of Animal Size on the Effectiveness of Peritoneal Oxygenation

This paper develops a scalable model of the dynamics of gas exchange during peritoneal oxygenation, motivated by the potential of such oxygenation to provide life support for patients with severe respiratory failure. The literature presents peritoneal oxygenation experiments for both large and small animals, including adult swine, rabbits, rats, and piglets. Results of these experiments suggest a potential discrepancy, with the benefits of peritoneal oxygenation possibly being stronger for smaller animals. We hypothesize that this size dependence is at least partially attributable to the effect of animal size on the ratio of peritoneal diffusion surface area to animal volume. The paper develops a scalable multi-compartment model of gas transport dynamics during peritoneal oxygenation. Simulating this model provides important insights regarding the potential impact of animal size on the viability of peritoneal oxygenation.

Parameter identification for a model of gas exchange dynamics during cycling

Parameter identification for a model of gas exchange dynamics during cycling

Parameter identification for a model of gas exchange dynamics during cycling

Parameter identification for a model of gas exchange dynamics during cycling

Development of a lightweight, portable, waterproof, and low power stem respiration system for trees

Stem respiration is a quantitatively important, but poorly understood component of ecosystem carbon cycling in terrestrial ecosystems. However, a dynamic stem gas exchange system for quantifying real-time stem carbon dioxide (CO2) efflux (Es) is not commercially available resulting in limited observations based on the static method where air is recirculated through a stem enclosure. The static method has limited temporal resolution, suffers from condensation issues, requires a leak-free enclosure, which is often difficult to verify in the field, and requires physically removing the chamber or flushing it with ambient air before starting each measurement.•With the goal of improving our quantitative understanding of biophysical, physiological, biochemical, and environmental factors that influence diurnal Es patterns, here we present a custom system for quantifying real-time stem Es in remote tropical forests.•The system is low cost, lightweight, and waterproof with low power requirements (1.2-2.4 W) for real-time monitoring of stem Es using a 3D printed dynamic stem chamber and a 12V car battery. The design offers control over the flow rate through the stem chamber, eliminates the need for a pump to introduce air into the chamber, and water condensation issues by removing water vapor prior to CO2 analysis.•Following a simple CO2 infrared gas analyzer (IRGA) calibration and match procedure with a 400-ppm standard, we quantified diurnal Es observations over a 24-hours period during the summer growing season from an ash tree (Fraxinus sp.) in Fort Collins, Colorado. The results are consistent with previous laboratory and field studies that show Es can be suppressed during the day relative to the night.

Photosynthetic Plasticity and Stomata Adjustment in Chromosome Segment Substitution Lines of Rice Cultivar KDML105 under Drought Stress

The impact of increasing drought periods on crop yields as a result of global climate change is a major concern in modern agriculture. Thus, a greater understanding of crop physiological responses under drought stress can guide breeders to develop new cultivars with enhanced drought tolerance. In this study, selected chromosome segment substitution lines of KDML105 (KDML105-CSSL) were grown in the Plant Phenomics Center of Kasetsart University in Thailand under well-watered and drought-stressed conditions. Physiological traits were measured by observing gas exchange dynamics and using a high-throughput phenotyping platform. Furthermore, because of its impact on plant internal gas and water regulation, stomatal morphological trait variation was recorded. The results show that KDML105-CSS lines exhibited plasticity responses to enhance water-use efficiency which increased by 3.62%. Moreover, photosynthesis, stomatal conductance and transpiration decreased by approximately 40% and plant height was reduced by 17.69%. Stomatal density tended to decrease and was negatively correlated with stomatal size, and stomata on different sides of the leaves responded differently under drought stress. Under drought stress, top-performing KDML105-CSS lines with high net photosynthesis had shorter plant height and improved IWUE, as influenced by an increase in stomatal density on the upper leaf side and a decrease on the lower leaf side.