Vapor Pressure Research Articles

Intraspecific variation in photosynthetic thermal acclimation in Fagus crenata seedlings from two populations growing at different elevations in northern Japan.

Plants can acclimate their photosynthesis to growth temperature, but the contribution of local adaptation to intraspecific variation in thermal acclimation of photosynthesis is not fully understood. Here, we experimentally investigated the photosynthetic thermal acclimation in Fagus crenata seedlings from two populations growing at different elevations and temperature regimes (low- and high-elevation sites) in northern Japan. We acclimated seedlings for 14-23days at 22°C (control) or 27°C (warm treatment) daytime temperature and obtained photosynthetic temperature-response curves in the range of 19 to 32°C. The optimum temperature of photosynthesis (Topt) was ca. 0.6°C higher in seedlings acclimated at 27°C than in those acclimated at 22°C, and it was significantly lower in seedlings with higher stomatal sensitivity to leaf-to-air vapor pressure deficit (VPD) than in those with lower sensitivity. The effects of warm treatment, population, and treatment-population interaction on Topt were not significant in the two-way analysis of variance, but the effect of treatment became significant when stomatal sensitivity to leaf-to-air VPD was included as a covariate in the model. Structural equation modelling (SEM) indicated that seedlings with lower root biomass had lower Topt because of the high stomatal sensitivity to leaf-to-air VPD. SEM also indicated that the way of shifting the Topt differed between the two populations: seedlings from a high-elevation site depended on decreasing photosynthetic rates at low temperatures for the increase in Topt but seedlings from a low-elevation site did not. We suggest that difference in thermal acclimation of photosynthesis between the two populations may reflect adaptation to different climate regimes and that belowground traits should be considered when investigating thermal acclimation capacity, especially in seedlings.

Infrared Spectroscopic and Physical Properties of Methanol Ices—Reconciling the Conflicting Published Band Strengths of an Important Interstellar Solid

Infrared spectroscopic observations have established the presence of solid methanol (CH3OH) in the interstellar medium and in solar system ices, but the abundance of frozen CH3OH cannot be deduced without accurate band strengths, optical constants, and reference spectra. In this paper we identify disagreements, omissions, and gaps in the literature on infrared (IR) intensities of methanol ices, including unaddressed concerns that reach back several decades. New spectra are presented with intensity measurements aided by new data on the index of refraction and density of solid CH3OH. The result is that the large discordant results from different laboratory groups can now be reconciled. Multiple ices have been used to determine, apparently for the first time, IR intensities of H2O + CH3OH mixtures of accurately known composition for use with observations of interstellar ices. Also for the first time, measurements on CH3OH ices with different thicknesses have allowed us to report both near-IR band strengths and optical constants for two near-IR features used by planetary scientists. We have used our new IR results to determine vapor pressures of solid CH3OH and have compared them to measurements made with a quartz-crystal microbalance. Thermal annealings of methanol ices have been carried out and phase changes in the solid state examined. Comparisons of our results to earlier work are presented where possible, and electronic versions of our new results are made available.

Preserving isohydricity: vertical environmental variability explains Amazon forest water use strategies.

Increases in hydrological extremes, including drought, are expected for Amazon forests. A fundamental challenge for predicting forest responses lies in identifying ecological strategies which underlie such responses. Characterization of species-specific hydraulic strategies for regulating water use, thought to be arrayed along an 'isohydric-anisohydric' spectrum, is a widely used approach. However, recent studies have questioned the usefulness of this classification scheme, because its metrics are strongly influenced by environments, hence can lead to divergent classifications even within the same species. Here, we propose an alternative approach positing that individual hydraulic regulation strategies emerge from the interaction of environments with traits. Specifically, we hypothesize that the vertical forest profile represents a key gradient in drought-related environments (atmospheric vapor pressure deficit, soil water availability) that drives divergent tree water use strategies for coordinated regulation of stomatal conductance (gs) and leaf water potentials (ΨL) with tree rooting depth, a proxy for water availability. Testing this hypothesis in a seasonal eastern Amazon forest in Brazil, we found that hydraulic strategies indeed depend on height-associated environments. Upper canopy trees, experiencing high VPD, but stable soil water access through deep rooting, exhibited isohydric strategies, defined by little seasonal change in the diurnal pattern of gs and steady seasonal minimum ΨL. By contrast, understory trees, exposed to less variable VPD but highly variable soil water availability, exhibited anisohydric strategies, with fluctuations in diurnal gs that increased in the dry season along with increasing variation in ΨL. Our finding that canopy height structures the coordination between drought-related environmental stressors and hydraulic traits provides a basis for preserving the applicability of the isohydric-to-anisohydric spectrum, which we show here may consistently emerge from environmental context. Our work highlights the importance of understanding how environmental heterogeneity structures forest responses to climate change, providing a mechanistic basis for improving models of tropical ecosystems.

Decoding stomatal characteristics regulating water use efficiency at leaf and plant scales in rice genotypes.

Stomatal traits in rice genotypes affect water use efficiency. Low-frequency small-size stomata correlate with whole plant efficiency, while low-frequency large-size stomata show intrinsic efficiency and responsiveness to vapour pressure deficit. Leaf surface and the patterning of the epidermal layer play a vital role in determining plant growth. While the surface helps in determining radiation interception, epidermal pattern of stomatal factors strongly regulate gas exchange and water use efficiency (WUE). This study focuses on identifying distinct stomatal traits among rice genotypes to comprehend their influence on WUE. Stomatal frequency ranged from 353 to 687 per mm2 and the size varied between 128.31 and 339.01 μm2 among 150 rice germplasm with significant variability in abaxial and adaxial surfaces. The cumulative water transpired and WUE determined at the outdoor phenomics platform, over the entire crop growth period as well as during specific hours of a 24h-day did not correlate with stomatal frequency nor size. However, genotypes with low-frequency and large-size stomata recorded higher intrinsic water use efficiency (67.04μmol CO2 mol-1 H2O) and showed a quicker response to varying vapour pressure deficit that diurnally ranged between 0.03 and 2.17kPa. The study demonstrated the role of stomatal factors in determining physiological subcomponents of WUE both at single leaf and whole plant levels. Differential expression patterns of stomatal regulatory genes among the contrasting groups explained variations in the epidermal patterning. Increased expression of ERECTA, TMM and YODA genes appear to contribute to decreased stomatal frequency in low stomatal frequency genotypes. These findings underscore the significance of stomatal traits in breeding programs and strongly support the importance of these genes that govern variability in stomatal architecture in future crop improvement programs.

Machine Learning Model to Predict Saturation Vapor Pressures of Atmospheric Aerosol Constituents

Machine Learning Model to Predict Saturation Vapor Pressures of Atmospheric Aerosol Constituents

Tree-ring based forest model calibrations with a deep learning algorithm

Process-based forest growth models are important tools for forest management and studies for forest growth, carbon sequestration, and forest dynamics. However, their reliable simulations rely not only on the quality of model construction but also on accurate parameters to appropriately depict various physiological and biophysical processes in the models. While explicit physiological measurements are excellent sources for model parameterization, they are not always readily available. It would be ideal to use easy-to-measure tree-ring data as a benchmark for parametrization, but such applications have been rare. Here we present a new approach to reasonably parameterize a stand growth model based on tree-ring data using deep learning algorithms. We integrated a stable carbon isotope (δ13C) version of a simple process-based stand growth model, 3-PG, into a recurrent neural network (RNN). The new 3PG-RNN model trained the RNN network and calibrated 3-PG parameters to minimize the mean squared error between the 3-PG outputs and targeted values. We then tested 3PG-RNN based on two Abies grandis stands located in Northern Idaho, USA. The results showed that the 3PG-RNN model was efficient in calibrating key parameters related to gas-exchange processes, including specifically quantum yield, maximum canopy conductance, and the slope function for stomatal responses to vapor pressure deficit. These calibrated parameters provided reasonable simulations for gas-exchanges similar to those constrained by explicit physiological observations. This was particularly true when both long-term diameter growth (estimated from tree-ring width) and tree-ring δ13C were used for model training. The RNN tool made it possible to use tree ring data as the key benchmark to calibrate the forest model and provide unbiased simulations for gas exchanges and forest growth with the RNN approach, which would greatly facilitate forest studies and management.

Tree-Ring δ13C and Intrinsic Water-Use Efficiency Reveal Physiological Responses to Climate Change in Semi-Arid Areas of North China

Climate change has had a widespread and profound impact on global temperature and precipitation patterns, especially in semi-arid areas. Plant δ13C and iWUE indicate the trade-off between carbon uptake and water loss, which is pivotal for understanding plant responses to climate change. Information about the long-term responses of the physiological and ecological processes of different tree species to climate change is also required. To investigate the impact of different forest stand structures and site conditions on long-term growth and physiological processes of coniferous and broad-leaved trees in the mountainous area of Beijing, we analyzed the tree-ring δ13C variation of four tree species (Platycladus orientalis, Pinus tabuliformis, Quercus variabilis, Robinia pseudoacacia) sampled from 64 plots with varying site and stand conditions. We found that the tree-ring δ13C of the four tree species varied from each other and was mainly affected by density and slope aspect, followed by slope and age. Both tree-ring δ13C and iWUE of the four tree species showed increasing trends over time, mechanistically linked to long-term changes in global CO2 concentration. This indicates the four native tree species have adapted well to climate change, and the risk of decline is relatively low. The increased iWUE translated into different growth patterns which varied with tree species, site, and stand condition. Different tree species have varying sensitivities to environmental factors. The iWUE of coniferous tree species is more sensitive to climate change than that of broad-leaved tree species, especially to temperature (T), the Standardized Precipitation Evapotranspiration Index (SPEI), and vapor pressure deficit (VPD).

Partitioning and controlling factors of evapotranspiration: 2. Dynamics and controls of ratio of transpiration to evapotranspiration at multiple timescales in agroforestry system

Understanding the dynamics and controls of ratio of transpiration to evapotranspiration (T/ET) at multiple timescales is essential to analyze ecohydrological processes and energy balance. However, the estimation of T/ET (i.e., partitioning of ET) is challenging, especially at short timescales. This study first generated time series of T/ET under farmland and apple orchards by the HYDRUS-1D constrained with isotope-based ET partitioning, and further analyzed the dynamics and controls of T/ET. The long-term averages of T/ET under farmland (0.64±0.04) were smaller and more variable than those under apple orchards (0.69±0.04 and 0.74±0.02 for apple trees of 20 and 30 years old). Individually, precipitation dominated T/ET variability at the total wavelet domain (0–256 month), annual (13–48 month), and interannual (121–256 month) timescales, while vapor pressure deficit (VPD) and relative humidity (RH) had dominant effects at monthly timescales (0–12 month). The monthly variability in T/ET can be explained by RH up to 77 %, while the interannual variability of T/ET was controlled by the combined effects of environmental factors up to 99 % (121–256 month). The results will help better understand how ET and its components in ecosystems respond to variable climates and land use types.

Patterns and Drivers of Bumblebee Diversity in Gansu

Understanding the influence of factors responsible for shaping community assemblage is crucial for biodiversity management and conservation. Gansu is one of the richest regions for bumblebee species in the world. We explored the distribution data of 52 bumblebee species collected in Gansu and its surroundings between 2002 and 2022, predicting habitat suitability based on 17 environmental variables using MaxEnt. The factors influencing community assemblage were assessed using canonical correspondence analysis. Net primary productivity, water vapor pressure, temperature seasonality, annual precipitation, and precipitation seasonality were some of the most influential drivers of species distributions. Based on Ward’s agglomerative cluster analysis, four biogeographic zones are described: the Southern humid zone, the Western Qilian snow mountain zone, the Eastern Loess plateau zone, and the Western dry mountain zone. In the clusters of grid cells based on beta diversity values, the Southern humid zone comprised 42.5% of the grid cells, followed by the Eastern Loess plateau zone (32.5%), the Western dry mountain zone (20%), and the Western Qilian snow mountain zone (5%). Almost all the environmental factors showed a significant contribution to the assemblages of bumblebees of different groups. Our findings highlight the need for better data to understand species biogeography and diversity patterns, and they provide key baseline data for refining conservation strategies.

Fabrication of three-dimensional bicontinuous porous aluminum by vapor phase dealloying

The development of lightweight, high-specific-surface-area, and exceptionally tough porous aluminum (Al) through dealloying has been consistently captured the attention of the porous metal field. However, widely employed dealloying approaches such as electrochemical dealloying (ECD) and liquid metal dealloying (LMD) face limitations in constructing porous metals with high chemical reactivities. In this study, we employed an emerging vapor phase dealloying (VPD) method, utilizing the differences in saturated vapor pressures among alloy constituents to selectively remove elements with high vapor pressures under optimized temperature and vacuum conditions. The VPD process, characterized by its chemical-free nature and the application of high temperatures, rapidly produces porous Al with varying ligament sizes from the MgZnAl system. The resulting porous Al, distinguished by its crack-free structure and substantial ligament size, exhibits remarkable toughness. The successful fabrication of porous Al using the VPD method effectively bridges the existing gap in generating porous metals with low melting points and high chemical reactivity through ECD and LMD methods. This advancement holds significance for broadening the range of systems and application fields for porous metals.

Coping with extremes: Responses of Quercus robur L. and Fagus sylvatica L. to soil drought and elevated vapour pressure deficit

Climate change, particularly droughts and heat waves, significantly impacts global photosynthesis and forest ecosystem sustainability. To understand how trees respond to and recover from hydrological stress, we investigated the combined effects of soil moisture and atmospheric vapour pressure deficit (VPD) on seedlings of the two major European broadleaved tree species Fagus sylvatica (FS) and Quercus robur (QR). The experiment was conducted under natural forest gap conditions, while soil water availability was strictly manipulated. We monitored gas exchange (net photosynthesis, stomatal conductance and transpiration rates), nonstructural carbohydrates (NSC) concentration in roots and stomatal morphometry (size and density) during a drought period and recovery. Our comparative empirical study allowed us to distinguish and quantify the effects of soil drought and VPD on stomatal behavior, going beyond theoretical models. We found that QR conserved water more conservatively than FS by reducing transpiration and regulating stomatal conductance under drought. FS maintained higher stomatal conductance and transpiration at elevated VPD until soil moisture became critically low. QR showed higher intrinsic water use efficiency than FS. Stomata density and size also likely played a role in photosynthetic rate and speed of recovery, especially since QR with its seasonal adjustments in stomatal traits (smaller, more numerous stomata in summer leaves) responded and recovered faster compared to FS. Our focal species showed different responses in NSC content under drought stress and recovery, suggesting possible different evolutionary pathways in coping with stress. QR mobilized soluble sugars, while FS relied on starch mobilization to resist drought. Although our focal species often co-occur in mixed forests, our study showed that they have evolved different physiological, morphological and biochemical strategies to cope with drought stress. This suggests that ongoing climate change may alter their competitive ability and adaptive potential in favor of one of the species studied.

Impact of extreme pre-monsoon drought on xylogenesis and intra-annual radial increments of two tree species in a tropical montane evergreen broad-leaved forest, southwest China.

Tropical montane evergreen broad-leaved forests cover the majority of forest areas and have high carbon storage in Xishuangbanna, southwest China. However, stem radial growth dynamics and their correlations with climate factors have never been analyzed in this forest type. By combining bi-weekly microcoring and high-resolution dendrometer measurements, we monitored xylogenesis and stem radius variations of the deciduous species Betula alnoides and the evergreen species Schima wallichii. We analyzed the relationships between weekly climate variables prior to sampling and the enlarging zone width or wall thickening zone width, as well as weekly radial increments and climate factors during two consecutive years (2020-2021) showing contrasting hydrothermal conditions in the pre-monsoon season. In the year 2020, which was characterized by a warmer and drier pre-monsoon season, the onset of xylogenesis and radial increments of B. alnoides and S. wallichi were delayed by three months and one month, respectively, compared to the year 2021. In 2020, xylem formation and radial increments were significantly reduced for B. alnoides, but not for S. wallichill. The thickness of enlarging zone and wall thickening zone in S. wallichill were positively correlated with relative humidity, minimum and mean air temperature, but were negatively correlated with vapor pressure deficit during 2020-2021. The radial increments of both species showed significant positive correlations with precipitation and relative humidity, and negative correlations with vapor pressure deficit and maximum air temperature during two years. Our findings reveal that drier pre-monsoon conditions strongly delay growth initiation and reduce stem radial growth, providing deep insights to understand tree growth and carbon sequestration potential in tropical forests under a predicted increase in frequent drought events.

A modified simplified SAFT EOS for VLE study of associating fluids

AbstractIn this study, the simplified version of statistical associating fluid theory (SAFT) equation of state (EOS) developed by Fu and Sandler is modified by replacing the dispersion term of this EOS with the Haghtalab–Mazloumi equation. This new SAFT‐based EOS has three adjustable parameters for non‐associating compounds and five adjustable parameters for associating compounds. The adjustable parameters of the new EOS are obtained by simultaneously fitting vapour pressures and liquid densities of pure substances. The new EOS shows better results in correlating vapour pressure and saturated liquid densities than SSAFT EOS for a selection of non‐associating and associating substances. Then, by using proper mixing rules, the new EOS is extended for mixtures. Both self‐associating and cross associating binary mixtures are used to test the capability of the new EOS in vapour–liquid equilibrium (VLE) calculations, and the results demonstrate good accuracy of the new EOS.

Comparative assessment of thermal oils and water as working fluids in parabolic trough collectors for enhanced solar power generation

Examining the thermal behavior of specific working fluids, namely Syltherm800 and TherminolVP-1, in parabolic trough collectors (PTCs) is imperative for enhancing power generation. This study addresses a crucial gap by conducting computational fluid dynamics simulations through COMSOL Multiphysics software and experimental tests to explore the advantages of utilizing thermal oils over water as a working fluid in PTCs. Experimental tests were performed on a water-based PTC in Iraq to validate the numerical model, considering various operating conditions such as input temperature (323.15–423.15 K) and mass flow rates (0.00926–0.0556 kg/s). Key parameters including output temperature, thermal efficiency, useful heat, and total heat losses were evaluated. The numerical model was validated against experimental data, showing good agreement with an overall discrepancy of 1.7% for the current experiments and 3.18% for literature results. The results indicated that Syltherm800, particularly with a high mass flow rate, outperformed TherminolVP-1 and water in terms of overall thermal performance. The optimal PTC thermal efficiency was achieved in July with a mass flow rate of 0.0556 kg/s and an input temperature of 348.15 K. The optimal range for PTC thermal efficiency over four months was between 50% and 70%. The endorsement of thermal oils in PTCs is supported by their low vapor pressure, superior thermal stability, and extended lifespan.

Sustainable Production of Dialkoxymethane Ethers and Related Acetals Using CO2, H2 and Alcohols or Diols

Dialkoxymethane (DAM) ethers, so‐called oxymethylene ethers (OMEs), are compounds constituted by a CH2‐unit bound to two identical alkoxy substituents. These compounds have showcased interesting technological applications as fuel additives or fuels, as a consequence of their interesting properties such as their low vapor pressure, high viscosity, cetane number and oxygen content. Moreover, they are also employed as environmentally benign solvents and bulk compounds useful in fine‐chemical industry. In addition, DAM ethers are considered formaldehyde surrogates. Industrially, dimethoxymethane (DMM) is still produced via two‐step protocol involving toxic formaldehyde that consists of a first step of methanol oxidation (Formox process). Hence, the development of more sustainable protocols for their synthesis is highly desired. Among the different strategies reported for DAM synthesis, its production from CO2/H2 and alcohols constitutes a practical, green and attractive alternative route. In this concept, a careful discussion of the developed catalytic protocols for synthesizing DAM from CO2/H2 or formic acid/H2 and alcohols/diols will be summarized. A special emphasis will be performed on the reaction mechanisms involved and the catalyst nature design and characterization.

Succession and seasonality of a Brazilian secondary tropical dry forest: Phenology and climate moderation

With large tracts of Tropical Dry Forests (TDF) in the Americas previously deforested, many places are currently undergoing secondary ecological succession. These processes vary in time and space, creating a landscape with forests of different ages or successional stages. These secondary forests need moreneed more understanding about how their ecosystem functionality is restored and recovering along the succession path. In particular, it is poorly understood how different successional stages moderate extremes of Essential Climatic Variables (ECV) such as temperature, relative humidity, soil moisture, and the fraction of Absorbed Photosynthetic Active Radiation (fAPAR). This paper, therefore, studies the linkages between high temporal resolution tower-based optical canopy phenology time series and seasonal changes in local ECV conditions between early (10–12 years) and late (50+ years) successional stage TDF in southeastern Brazil. We compare diurnal and seasonal patterns of understory ECVs between early/late plots and investigate the canopy’s Climate Moderating Capacity (CMC). Our data indicate at least 100 mm of precipitation within two weeks is necessary to initiate leaf flushing in this TDF. We also find that soil moisture and daytime air humidity strongly correlate (R2 > 0.75) with seasonal patterns in canopy vegetation greenness indices and fAPAR with a cross-correlation time lag peak of 12–15 days. Our results suggest that the late stage is more effective at cooling (−1.4 ± 0.6 °C vs −0.8 ± 0.6 °C) and reducing daytime evaporation (−0.41 ± 0.2 kPa vs −0.18 ± 0.12 °C) in the understory during the growing season than the early stage. Results suggest that the CMC varies with seasonal canopy leaf area dynamics and with heat and moisture scales, becoming significantly stronger when temperatures and vapour pressure deficits were highest, and correlated strongly with canopy fAPAR dynamics (R2 = 0.82). These findings demonstrate that TDFs can effectively regain microclimatic buffering capacity.

Estimation of best geometric and operational parameters of a nanophotonics-enabled solar membrane desalination system: A numerical investigation

Nanophotonics-enabled solar membrane desalination (NESMD) system is a sustainable method to address water scarcity by desalinating seawater using solar energy. A layer of nanoparticles absorbs heat, creating localized heating within feed channel, which generates a vapor pressure difference between feed and permeate channels. Distillate water is collected in permeate channel. Numerical modelling of NESMD system, integrating optical and thermal modules in COMSOL Multiphysics, efficiently enumerates distillate flux at specified locations under varying ambient conditions. Reliability of the simulation model is confirmed through validation against in-house experimental results. A set of most effective dimensions and component specifications for NESMD system are computed that maximize distillate flux. Setup width exhibits invariant distillate flux within a range of 2–30 cm, while a feed thickness of 2 mm yields maximum distillate flux, with no change observed for permeate thickness within a range of 2–10 mm. An optimal setup length is determined within 80–200 cm range under varying operating conditions. Membrane porosity of 0.85 is selected to balance both vapor diffusivity and mechanical strength. The optimum membrane thickness lies within 180–225 µm range. An NESMD system with these best suited specifications is demonstrated to produce freshwater at the rate of 4.63 l/m2 per day.

Ab Initio Prediction of Vapor Pressure for Diverse Atomic Layer Deposition Precursors.

Understanding the saturated vapor pressure (Pvap) is vital for evaluating atomic layer deposition (ALD) precursors, as it directly influences the ALD temperature window and, by extension, the processability of compounds. The early estimation of vapor pressure ranges is crucial during the initial stages of novel precursor design, reducing the reliance on empirical synthesis or experimentation. However, predicting vapor pressure through computer simulations is often impeded by the scarcity of suitable empirical force fields for molecular dynamics simulations. This challenge is further compounded by the diverse chemical substances and the introduction of new elements into modern ALD processes, necessitating robust force fields that can accommodate metals, organics, and halides. In response, this study introduces a novel approach utilizing a quantum mechanically derived force field for the prediction of vapor pressure across a wide spectrum of potential ALD precursors. This approach enables the creation of system-specific force fields through parametrization based on ab initio calculations for a single molecule. We develop a comprehensive workflow to simulate both liquid and gaseous equilibrium phases, allowing the calculation of vapor pressure across a wide temperature range. Our methodology has been validated with a diverse set of ALD precursors, demonstrating its robustness in predicting Pvap at specified temperatures. The approach yields a Pearson's correlation coefficient (R2) greater than 0.9 on a logarithmic scale and a root-mean-squared deviation in self-solvation-free energies as low as 1.3 kcal mol-1. This innovative workflow, which does not require any prior experimental data, marks a significant advancement in the computer-aided design of novel ALD precursors, paving the way for accelerating developments in technology.

Determination of Various Physical–Chemical Properties of bis(2-Methylbutyl) Itaconate and bis(3-Methylbutyl) Itaconate from Bio-Based Resources

Alternative sources for an industrial production of essential substances represent an exciting field of study for many researchers. Based on the previous research, itaconic acid and its esters were intensively studied as one of the sources. This paper relates to a determination of the basic physical–chemical properties of bis(2-methylbutyl) itaconate and bis(3-methylbutyl) itaconate that are produced from itaconic acid and 2-methylbutan-1-ol and 3-methylbutan-1-ol, respectively, from biomass. According to our best knowledge, physical–chemical properties of these substances, such as density, viscosity, and saturated vapor pressure, are not presented in the literature, and these are important for the future research of their production.

Study of Seasonal Incidence of Rice Earhead Bug (Coreidae: Hemiptera)

This study investigates the relationship between climatic factors and the population dynamics of the rice earhead bug (Leptocorisa acuta) in Balaghat district of Madhya Pradesh. Through correlational analysis, we examined the associations between rainfall, rainy days, morning relative humidity (RH), evening RH, evening vapour pressure, wind velocity, maximum temperature, morning vapour pressure, evaporation, sunshine, and the prevalence of rice earhead bugs. Results indicate a negative correlation between rice earhead bug population and both rainfall and rainy days, suggesting a potential suppression effect of increased precipitation on bug abundance. Morning RH, evening RH, evening vapour pressure, and wind velocity showed non-significant negative correlations with bug population, indicating that these factors may have limited influence on bug dynamics in our study area. Conversely, a positive non-significant correlation was observed between rice earhead bug population and maximum temperature, morning vapour pressure, evaporation, and sunshine. This implies that higher temperatures and increased solar radiation may have a subtle positive effect on bug abundance, although further investigation is warranted to elucidate the underlying mechanisms. Overall, our findings shed light on the complex interplay between climatic factors and rice earhead bug dynamics, highlighting the importance of considering multiple variables in pest management strategies for rice cultivation.