Engineering Commons^™

Low-Level Groundwater Atrazine In High Atrazine Usage Nebraska Counties: Likely Effects Of Excessive Groundwater Abstraction, Moses New-Aaron, Olufemi P. Abimbola, Raheleh Mohammadi, Oluwaseun Famojuro, Zaeema Naveed, Azar M Abadi, Jesse E. Bell, Shannon Bartelt-Hunt, Eleanor G. Rogan

Department of Biological Systems Engineering: Papers and Publications

Recent studies observed a correlation between estrogen-related cancers and groundwater atrazine in eastern Nebraska counties. However, the mechanisms of human exposure to atrazine are unclear because low groundwater atrazine concentration was observed in counties with high cancer incidence despite having the highest atrazine usage. We studied groundwater atrazine fate in high atrazine usage Nebraska counties. Data were collected from Quality Assessed Agrichemical Contaminant Nebraska Groundwater, Parameter–Elevation Regressions on Independent Slopes Model (PRISM), and water use databases. Descriptive statistics and cluster analysis were performed. Domestic wells (59%) were the predominant well type. Groundwater atrazine was affected by well depth. Clusters consisting …

Gis-Based Volunteer Cotton Habitat Prediction And Plant-Level Detection With Uav Remote Sensing, Tianyi Wang, Xiaohan Mei, J. Alex Thomasson, Chenghai Yang, Xiongzhe Han, Pappu Kumar Yadav, Yeyin Shi

Department of Biological Systems Engineering: Papers and Publications

Volunteer cotton plants germinate and grow at unwanted locations like transport routes and can serve as hosts for a harmful cotton pests called cotton boll weevils. The main objective of this study was to develop a geographic information system (GIS) framework to efficiently locate volunteer cotton plants in the cotton production regions in southern Texas, thus reducing time and economic cost for their removal. A GIS network analysis tool was applied to estimate the most likely routes for cotton transportation, and a GIS model was created to identify and visualize potential areas of volunteer cotton growth. The GIS model indicated …

Global Analysis Of Differential Gene Expression Within The Porcine Conceptus Transcriptome As It Transitions Through Spherical, Ovoid, And Tubular Morphologies During The Initiation Of Elongation, Sophie C. Walsh, Jeremy R. Miles, Brittney N. Keel, Lea A. Rempel, Elane C. Wright‐Johnson, Amanda K. Lindholm‐Perry, William T. Oliver, Angela K. Pannier

Department of Biological Systems Engineering: Papers and Publications

This study aimed to identify transcriptome differences between distinct or transitional stage spherical, ovoid, and tubular porcine blastocysts throughout the initiation of elongation. We performed a global transcriptome analysis of differential gene expression using RNA‐Seq with high temporal resolution between spherical, ovoid, and tubular stage blastocysts at specific sequential stages of development from litters containing conceptus populations of distinct or transitional blastocysts. After RNA‐Seq analysis, significant differentially expressed genes (DEGs) and pathways were identified between distinct morphologies or sequential development stages. Overall, 1898 significant DEGs were identified between distinct spherical and ovoid morphologies, with 311 total DEGs between developmental stages …

Injectable Decellularized Nucleus Pulposus Tissue Exhibits Neuroinhibitory Properties, Logan M. Piening, David J. Lillyman, Fei San Lee, Alvaro Moreno Lozano, Jeremy R. Miles, Rebecca A. Wachs

Department of Biological Systems Engineering: Papers and Publications

Background: Chronic low back pain (LBP) is a leading cause of disability, but treatments for LBP are limited. Degeneration of the intervertebral disc due to loss of neuroinhibitory sulfated glycosaminoglycans (sGAGs) allows nerves from dorsal root ganglia to grow into the core of the disc. Treatment with a decellularized tissue hydrogel that contains sGAGs may inhibit nerve growth and prevent discassociated LBP.

Methods: A protocol to decellularize porcine nucleus pulposus (NP) was adapted from previous methods. DNA, sGAG, α-gal antigen, and collagen content were analyzed before and after decellularization. The decellularized tissue was then enzymatically modified to be …

Corn Fiber As A Biomass Feedstock For Production Of Succinic Acid, Lisbeth Vallecilla-Yepez, Divya Ramchandran, Dianna Long, Rajib Saha, Mark R. Wilkins

Department of Biological Systems Engineering: Papers and Publications

The selection of an economical carbon source is a fundamental parameter to establish a successful industrial succinic acid (SA) bioprocess. In this work, corn fiber (CF), a renewable and an inexpensive source of carbohydrates, was successfully used for bioproduction of SA. Optimized liquid hot water (LHW) pretreatment followed by enzymatic hydrolysis were used to obtain corn fiber hydrolysate (CFH). Results in batch fermentation with Actinobacillus succinogenes showed that a control solution mimicking CFH produced 28.7 g/L of SA with a yield of 0.67 g SA/g sugars, while fermentation of CFH produced 27.8 g/L of SA with a yield of 0.61 …

Preferential Flow In Riparian Buffers: Current Research And Future Needs., Derek M. Heeren, Lucie Guertault, Kyle Mankin

Department of Biological Systems Engineering: Papers and Publications

Preferential flow in riparian buffers can substantially compromise their effectiveness in reducing contaminants from overland runoff. The objective of this article is to introduce a collection of five articles on current research into subsurface preferential flow measurement, visualization, modeling, and impacts on contaminant fate and transport at scales ranging from the subsurface pore scale to the plot scale to the watershed scale. This collection presents selected works from a broader invited session on “Preferential flow and piping in riparian buffers” at the 2020 ASABE Annual International Meeting. Major findings include: new methodologies, such as light transmission and geophysics, to characterize …

Inter-Relationships Between Water Depletion And Temperature Differential In Row Crop Canopies In A Sub-Humid Climate, Jasreman Singh, Yufeng Ge, Derek M. Heeren, Elizabeth Walter-Shea, Christopher M.U. Neale, Suat Irmak, Wayne Woldt, Geng Bai, Sandeep Bhatti, Mitchell S. Maguire

Department of Biological Systems Engineering: Papers and Publications

Irrigation has a great impact on global food security as it contributes to the majority of the world’s agricultural food supply. It is essential to judiciously utilize water resources through efficient irrigation management since the majority of U.S. groundwater aquifers are rapidly depleting. Thus, quantification of the relationships between water depletion and environmental factors is important for understanding crop response to varying levels of water stresses that depletion can cause. The objectives of this research were to: 1) investigate the relationship between root zone water depletion (D_rw) and canopy temperature differential (ΔT) at different ranges of D_{rw …}

Characterization Of Tea (Camellia Sinensis) Granules For Quality Grading Using Computer Vision System, Md Towfiqur Rahman, Sabiha Ferdous, Mariya Sultana Jenin, Tanjina Rahman Mim, Masud Alam, Muhammad Rashed Al Mamun

Department of Biological Systems Engineering: Papers and Publications

Tea (Camellia sinensis) has been found as an important medicinal beverage for human which is consumed all over the world. Primarily, the majority of tea is being cultivated in Asia and Africa, however it is commercially produced by more than 60 countries. Though substantial amount is produced, its processing system is still underdeveloped which leads to decrease in export opportunity as well as low monetary value. Moreover, the traditional method of tea grading and sorting is laborious, inefficient, and costly which ultimately produces the low-quality heterogeneous products. Processing and grading of tea granules after drying is very important …

Disturbance Triggers Non-Linear Microbe–Environment Feedbacks, Aditi Sengupta, Sarah J. Fansler, Rosalie K. Chu, Robert E. Danczak, Vanessa A. Garayburu-Caruso, Lupita Renteria, Hyun-Seob Song, Jason Toyoda, Jacqueline Wells, James C. Stegen

Department of Biological Systems Engineering: Papers and Publications

Conceptual frameworks linking microbial community membership, properties, and processes with the environment and emergent function have been proposed but remain untested. Here we refine and test a recent conceptual framework using hyporheic zone sediments exposed to wetting–drying transitions. Our refined framework includes relationships between cumulative properties of a microbial community (e.g., microbial membership, community assembly properties, and biogeochemical rates), environmental features (e.g., organic matter thermodynamics), and emergent ecosystem function. Our primary aim was to evaluate the hypothesized relationships that comprise the conceptual framework and contrast outcomes from the whole and putatively active bacterial and archaeal communities. Throughout the system we …

Making Space For Social And Emotional Learning In Science Education, Erin Ingram, Kristie Reddick, Jessica M. Honaker, Gwen A. Pearson

Department of Biological Systems Engineering: Papers and Publications

Social-emotional learning (SEL) is known to improve student outcomes but is rarely combined with STEM. In this paper we present an action research study to examine the impact of a STEM + SEL curriculum intervention to address a real-world school conflict. One hundred sixth–eighth graders and four teachers participated in an in-person facilitation of a SEL Arthropod curriculum, DIFFERENT. After the intervention, students completed open-ended couplet statements about arthropod behavior, tarantulas, and humans designed to measure sentiment change. Answers were manually coded using inductive coding on a scale of negative (1) to positive (5). Statement sentiments significantly shifted from negative …

Biofiltration Application At Ethanol Plants: Analysis Of Aqueous Streams And Treatment Of Vocs, Katie Mowat

Department of Environmental Engineering: Theses and Student Research

The United States used 14.5 billion gallons of the biofuel ethanol in 2019 produced primarily (82%) in dry-mill corn ethanol plants. These plants produce volatile organic compounds (VOCs) — some of which are hazardous air pollutants (HAPs) — during production. Traditional treatment methods for gaseous emissions use a large quantity of water or natural gas. Thus, a bio-trickling filter (BTF) is considered an innovative alternative treatment method. A lab-scale BTF was used in this study to look at the effect of ethanol concentration and temperature on the treatment of a HAPs mixture. Gaseous and aqueous testing were performed on the …

Oxygen Reactive Polymers For Treatment Of Traumatic Brain Injury, Parick S. Stayton, Menko P. Ypma, Peter A. Chiarelli, Joshua Sang Hun Park, Richard G. Ellenbogen, Julia Mengyun Xu, Pierre D. Mourad, Donghoon Lee, Anthony Convertime, Forrest M. Kievit

Department of Biological Systems Engineering: Papers and Publications

Methods and compositions for treating traumatic brain injury . The methods and compositions utilize a multi - functional oxygen reactive polymer ( ORP ) that includes repeating units that include a reactive oxygen species ( ROS ) scavenging group and a polyalkylene oxide group . For theranostic applications , the oxygen reactive polymer fur ther includes a diagnostic group .

Robotic Technologies For High-Throughput Plant Phenotyping: Contemporary Reviews And Future Perspectives, Abbas Atefi, Yufeng Ge, Santosh Pitla, James Schnable

Department of Biological Systems Engineering: Papers and Publications

Phenotyping plants is an essential component of any effort to develop new crop varieties. As plant breeders seek to increase crop productivity and produce more food for the future, the amount of phenotype information they require will also increase. Traditional plant phenotyping relying on manual measurement is laborious, time-consuming, error-prone, and costly. Plant phenotyping robots have emerged as a high-throughput technology to measure morphological, chemical and physiological properties of large number of plants. Several robotic systems have been developed to fulfill different phenotyping missions. In particular, robotic phenotyping has the potential to enable efficient monitoring of changes in plant traits …

Comparison Of Promoter, Dna Vector, And Cationic Carrier For Efficient Transfection Of Hmscs From Multiple Donors And Tissue Sources, Tyler Kozisek, Andrew Hamann, Luke Samuelson, Miguel Fudolig, Angela K. Pannier

Department of Biological Systems Engineering: Papers and Publications

Human mesenchymal stem cells (hMSCs) are primary cells with high clinical relevance that could be enhanced through genetic modification. However, gene delivery, particularly through nonviral routes, is inefficient. To address the shortcomings of nonviral gene delivery to hMSCs, our lab has previously demonstrated that pharmacological “priming” of hMSCs with clinically approved drugs can increase transfection in hMSCs by modulating transfection-induced cytotoxicity. However, even with priming, hMSC transfection remains inefficient for clinical applications. This work takes a complementary approach to addressing the challenges of transfecting hMSCs by systematically investigating key transfection parameters for their effect on transgene expression. Specifically, we investigated …

Modeling Vadose Zone Hydrology: Lecture Notes, Derek M. Heeren, Dean Eisenhauer

Open Educational Resources for Engineering

Modeling Vadose Zone Hydrology is a graduate-level course offered biennially in the Department of Biological Systems Engineering. Topics included hydraulic properties of porous media, application of Darcy's Law in variably saturated media, hydrologic and transport processes in the vadose zone, and solution of steady and unsteady flow problems using numerical techniques. A graphical approach for characterizing vertical one-dimensional problems with energy head profiles was emphasized. Common one-dimensional flow and transport problems were solved analytically. The course was taught using a combination of lecture notes and PowerPoint presentations. The lecture notes from 2021, captured using the Microsoft Whiteboard app with a …

Uavs For Vegetation Monitoring: Overview And Recent Scientific Contributions, Ana I. De Castro, Yeyin Shi, Joe Mari Maja, Jose M. Peña

Department of Biological Systems Engineering: Papers and Publications

This paper reviewed a set of twenty-one original and innovative papers included in a special issue on UAVs for vegetation monitoring, which proposed new methods and techniques applied to diverse agricultural and forestry scenarios. Three general categories were considered: (1) sensors and vegetation indices used, (2) technological goals pursued, and (3) agroforestry applications. Some investigations focused on issues related to UAV flight operations, spatial resolution requirements, and computation and data analytics, while others studied the ability of UAVs for characterizing relevant vegetation features (mainly canopy cover and crop height) or for detecting different plant/crop stressors, such as nutrient content/deficiencies, water …

Early Detection Of Encroaching Woody Juniperus Virginiana And Its Classification In Multi-Species Forest Using Uas Imagery And Semantic Segmentation Algorithms, Lin Wang, Yuzhen Zhou, Qiao Hu, Zhenghong Tang, Yufeng Ge, Adam Smith, Tala Awada, Yeyin Shi

Department of Biological Systems Engineering: Papers and Publications

Woody plant encroachment into grasslands ecosystems causes significantly ecological destruction and economic losses. Effective and efficient management largely benefits from accurate and timely detection of encroaching species at an early development stage. Recent advances in unmanned aircraft systems (UAS) enabled easier access to ultra-high spatial resolution images at a centimeter level, together with the latest machine learning based image segmentation algorithms, making it possible to detect small-sized individuals of target species at early development stage and identify them when mixed with other species. However, few studies have investigated the optimal practical spatial resolution of early encroaching species detection. Hence, we …

Exploration Of The Sludge Biodiesel Pathway, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Wastewater sludge is an overlooked source of fat, oil, and grease (FOG) that could be converted into biodiesel. The United States produces about 8 million tons of sludge per year. The disposal cost for this amount of sludge is about 2 billion US dollars. The widespread availability and low cost of sludge compared to other biodiesel raw materials make it an economical choice for a renewable fuel. Using sludge as a raw material can produce 25 to 30 mg per gram of fatty acid methyl ester (FAME); the main component of biodiesel. Sludge biodiesel has the potential of transforming a …

Environmental Impacts Of Overdesign In Small Community Water Resource Recovery Facilities, Andrew Pham

Department of Environmental Engineering: Theses and Student Research

Although water resource recovery facilities (WRRFs) reduce environmental impacts related to water quality, their construction and operation result in negative environmental impacts in other categories. Past research into Nebraska WRRFs investigated variables determining energy intensity, opportunities and barriers for energy efficiency improvements, and environmental impacts of the construction and operation phase. This leads to the research question of what design practices can be considered to reduce the environmental impacts.

The Life Cycle Assessment (LCA) methodology was used to evaluate and compare the inventory and environmental impacts of nine small WRRFs, most of which are serving slow growing or declining populations. …

Utilizing Digital Image Processing And Two‑Source Energy Balance Model For The Estimation Of Evapotranspiration Of Dry Edible Beans In Western Nebraska, Wei‑Zhen Liang, Isabella Possignolo, Xin Qiao, Kendall Dejonge, Suat Irkmak, Derek M. Heeren, Daran Rudnick

Department of Biological Systems Engineering: Papers and Publications

Having an accurate yet simple method to estimate crop evapotranspiration ( ET_C) is a vital component of reliable irrigation scheduling. In this study, two versions of the two-source energy balance (TSEB) model: the TSEB model with the Priestley–Taylor equation (TSEB-PT) and the Penman–Monteith equation (TSEB-PM), were used to estimate ET_C of dry edible beans in western Nebraska. Compared with previous studies, this study is unique in that a Visual Basic software—Crop Canopy Image Analyzer (CCIA) was developed to process digitally captured RGB canopy images to obtain necessary canopy cover (CC) parameters for the TSEB models such as …

Comparative Study Of Human Pluripotent Stem Cell-Derived Endothelial Cells In Hydrogel-Based Culture Systems, Zhanqi Wang, Fuxing Zuo, Qing Liu, Xuesheng Wu, Qian Du, Yuguo Lei, Zhangmin Wu, Haishuang Lin

Department of Biological Systems Engineering: Papers and Publications

Human pluripotent stem cell (hPSC)-derived endothelial cells (ECs) are promising cell sources for drug discovery, tissue engineering, and studying or treating vascular diseases. However, hPSC-ECs derived from different culture methods display different phenotypes. Herein, we made a detailed comparative study of hPSC-ECs from three different culture systems (e.g., 2D, 3D PNIPAAm-PEG hydrogel, and 3D alginate hydrogel cultures) based on our previous reports. We expanded hPSCs and differentiated them into ECs in three culture systems. Both 3D hydrogel systems could mimic an in vivo physiologically relevant microenvironment to protect cells from shear force and prevent cell agglomeration, leading to a high …

Determination Of Vadose Zone And Saturated Zone Nitrate Lag Times Using Long-Term Groundwater Monitoring Data And Statistical Machine Learning, Martin J. Wells, Troy E. Gilmore, Natalie Nelson, John K. Bohlke

Department of Biological Systems Engineering: Papers and Publications

In this study, we explored the use of statistical machine learning and long-term groundwater nitrate monitoring data to estimate vadose zone and saturated zone lag times in an irrigated alluvial agricultural setting. Unlike most previous statistical machine learning studies that sought to predict groundwater nitrate concentrations within aquifers, the focus of this study was to leverage available groundwater nitrate concentrations and other environmental variables to determine mean regional vertical velocities (transport rates) of water and solutes in the vadose zone and saturated zone (3.50 and 3.75 m yr−1 , respectively). The statistical machine learning results are consistent with two primary …

Role Of Nadþ In Regulating Cellular And Metabolic Signaling Pathways, Sara Amjad, Sabah Nisar, Ajaz A. Bhat, Ab Rauf Shah, Michael P. Frenneaux, Khalid Fakhro, Mohammad Haris, Ravinder Reddy, Zoltan Patay, Joseph Baur, Puneet Bagga

Department of Biological Systems Engineering: Papers and Publications

Background: Nicotinamide adenine dinucleotide (NAD⁺), a critical coenzyme present in every living cell, is involved in a myriad of metabolic processes associated with cellular bioenergetics. For this reason, NAD⁺ is often studied in the context of aging, cancer, and neurodegenerative and metabolic disorders.

Scope of review: Cellular NAD⁺ depletion is associated with compromised adaptive cellular stress responses, impaired neuronal plasticity, impaired DNA repair, and cellular senescence. Increasing evidence has shown the efficacy of boosting NAD⁺ levels using NAD⁺ precursors in various diseases. This review provides a comprehensive understanding into the role of NAD^{+ …}

Historical Contingency In Microbial Resilience To Hydrologic Perturbations, Hyun-Seob Song, James C. Stegen, Emily B. Graham, Timothy D. Scheibe

Department of Biological Systems Engineering: Papers and Publications

Development of reliable biogeochemical models requires a mechanistic consideration of microbial interactions with hydrology. Microbial response to and its recovery after hydrologic perturbations (i.e., resilience) is a critical component to understand in this regard, but generally difficult to predict because the impacts of future events can be dependent on the history of perturbations (i.e., historical contingency). Fundamental issues underlying this phenomenon include how microbial resilience to hydrologic perturbations is influenced by historical contingency and how their relationships vary depending on the characteristics of microbial functions. To answer these questions, we considered a simple microbial community composed of two species that …

Modeling The Release And Spreading Of Permanganate From Aerated Slow-Release Oxidants In A Laboratory Flow Tank, Ann Kambhu, Yusong Li, Troy E. Gilmore, Steve D. Comfort

School of Natural Resources: Faculty Publications

Aerated, slow-release oxidants are a relatively new technology for treating contaminated aquifers. A critical need for advancing this technology is developing a reliable method for predicting the radius of influence (ROI) around each drive point. In this work, we report a series of laboratory flow tank experiments and numerical modeling efforts designed to predict the release and spreading of permanganate from aerated oxidant candles (oxidant-wax composites). To mimic the design of the oxidant delivery system used in the field, a double screen was used in a series of flow tank experiments where the oxidant was placed inside the inner screen …

Combining Electrochemical Nitrate Reduction And Anammox For Treatment Of Nitrate-Rich Wastewater: A Short Review, Xinyi Zou, Chongjun Chen, Changhong Wang, Qun Zhang, Zhuowei Yu, Haiping Wu, Chao Zhuo, Tian C. Zhang

Department of Civil and Environmental Engineering: Faculty Publications

Treatment of nitrate-rich wastewater is important but challenging for the conventional biological denitrification process. Here, we propose combining the electrochemical reduction and anaerobic ammonium oxidation (anammox) processes together for treatment of nitrate-rich wastewater. This article reviews the mechanism and current research status of electrochemical reduction of nitrate to ammonium as well as the mechanism and applicability of the anammox process. This article discusses the principles, superiorities, and challenges of this combined process. The feasibility of the combined process depends on the efficiency of electrochemical nitrate reduction to ammonium and the conditions in the anammox process to use the reduced ammonium …

Nebraska Water Center Annual Report 2019-2020

Literature from The Nebraska Water Center

Contents

Introduction: Foreword • Director’s Letter • Nebraska Water Center (NWC) Overview and Timeline • In Memoriam: Kyle Hoagland

Research • Water Sciences Laboratory • Nebraska Vadose Zone Program • Ogallala Water Coordinated Agriculture Project • Water for Agriculture Project • Greeley Award • U.S. Geological Survey 104b Projects

Extension & Outreach: NWC Events • Nebraska Nitrate Initiative • Bazile Groundwater Management Area • Water and Integrated Crops Hub • Water Faculty Directory • State Legislative Funding • Water Resources Advisory Panel

Teaching: Know Your Well • Sorab Panday Spotlight • NWC Postdoc Profiles • NWC Student Intern Profiles • …

Quantification Of Nitric Oxide Concentration Using Single-Walled Carbon Nanotube Sensors, Jakob Meier, Joseph Stapleton, Eric M. Hofferber, Abigail Haworth, Stephen D. Kachman, Nicole M. Iverson

Department of Biological Systems Engineering: Papers and Publications

Nitric oxide (NO), a free radical present in biological systems, can have many detrimental effects on the body, from inflammation to cancer. Due to NO’s short half-life, detection and quan- tification is difficult. The inability to quantify NO has hindered researchers’ understanding of its impact in healthy and diseased conditions. Single-walled carbon nanotubes (SWNTs), when wrapped in a specific single-stranded DNA chain, becomes selective to NO, creating a fluorescence sensor. Unfortunately, the correlation between NO concentration and the SWNT’s fluorescence intensity has been difficult to determine due to an inability to immobilize the sensor without altering its properties. Through the …

Modeling And Prioritizing Interventions Using Pollution Hotspots For Reducing Nutrients, Atrazine And E. Coli Concentrations In A Watershed, Olufemi P. Abimbola, Aaron R. Mittelstet, Tiffany Messer, Elaine Berry, Anna Van Griensven

Department of Biological Systems Engineering: Papers and Publications

Excess nutrients and herbicides remain two major causes of waterbody impairment globally. In an attempt to better understand pollutant sources in the Big Sandy Creek Watershed (BSCW) and the prospects for successful remediation, a program was initiated to assist agricultural producers with the implementation of best management practices (BMPs). The objectives were to (1) simulate BMPs within hotspots to determine reductions in pollutant loads and (2) to determine if water-quality standards are met at the watershed outlet. Regression-based load estimator (LOADEST) was used for determining sediment, nutrient and atrazine loads, while artificial neural networks (ANN) were used for determining E. …

Assessing Different Plant-Centric Water Stress Metrics For Irrigation Efficacy Using Soil-Plant-Atmosphere-Continuum Simulation, Jingwen Zhang, Kaiyu Guan, Bin Peng, Ming Pan, Wang Zhou, Robert F. Grant, Trenton E. Franz, Daran Rudnick, Derek M. Heeren, Andrew Suyker, Yi Yang, Genghong Wu

Department of Biological Systems Engineering: Papers and Publications

Understanding plant water stress (PWS) in the soil-plant-atmosphere-continuum (SPAC) that connects water supply from soil, water demand from atmosphere, and plant self-regulation is a prerequisite for efficient irrigation in response to water scarcity. Currently, PWS can be defined in various ways, for example, based on environmental factors and/or plant-centric metrics. The environment-based metrics usually do not take plants into consideration. Regarding the existing plant-centric metrics, their interconnections and abilities to capture the physical water constraints from both soil water supply and atmospheric water demand are still unclear. This research investigates the theoretical foundations behind different PWS metrics, and assesses their …