Plant Water Interactions Research Articles

The effect of amorphous silica on soil–plant–water relations in soils with contrasting textures

This study investigates how amorphous silica (ASi) influences soil–plant–water interactions in distinct soil textures. A sandy loam and silty clay soil were mixed with 0 and 2% ASi, and their impact on soil retention and soil hydraulic conductivity curves were determined. In parallel, tomato plants (Solanum lycopersicum L.) were grown in experimental pots under controlled conditions. When plants were established, the soil was saturated, and a controlled drying cycle ensued until plants reached their wilting points. Soil water content, soil water potential, plant transpiration rate, and leaf water potential were monitored during this process. Results indicate a positive impact of ASi on the sandy loam soil, enhancing soil water content at field capacity (FC, factor of 1.3 times) and at permanent wilting point (PWP, a factor of 3.5 times), while its effect in silty clay loam was negligible (< 1.05 times). In addition, the presence of ASi prevented a significant drop in soil hydraulic conductivity (Kh\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${K}_{h}$$\\end{document}) at dry conditions. The Kh\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${K}_{h}$$\\end{document} of ASi-treated sandy loam and silty clay at PWP were 4.3 times higher than their respective control. Transpiration rates in plants grown in ASi-treated sandy loam soil under soil drying conditions were higher than in the control, attributed to improved soil hydraulic conductivity. At the same time, no significant difference was observed in the transpiration of plants treated with ASi in silty clay soil. This suggests ASi boosts soil–plant–water relationships in coarse-textured soils by maintaining heightened hydraulic conductivity, with no significant effect on fine-textured soils.

Water Uptake Characteristics of Stipa bungeana Trin: Affected by Subsidence in the Coal Mining Areas of Northwest China

Revealing the water use pattern of plants influenced by coal-mining-caused land subsidence is crucial to understand plant–water interactions and guide ecological restoration. However, available information on herbaceous plants, the dominant species in most arid and semi-arid regions with abundant coal resources, remains inadequate. We investigated the water use patterns of Stipa bungeana Trin. by measuring soil water content, root distribution, and stable isotopes of hydrogen (δ2H) and oxygen (δ18O) of soil water and plant stem water both before and after a rainfall event. The results revealed that prior to rainfall, both areas exhibited a low soil water content with no discernible difference in soil drought. However, the soil waters δ2H and δ18O were found to be more enriched at varying depths within the subsidence area, indicating a heightened level of soil evaporation. Both soil water content and soil water isotopic composition responded sensitively to rainfall, with rainfall primarily replenishing the shallow layer (0–20 cm), thereby reflecting an infiltration mode dominated by piston flow. More water seeped into deeper soil layers in the subsidence area compared to the non-subsidence area, with more preferential flow. Before rainfall, the sources of plant water uptake were consistent both at shallow and deep soil layers, implying that the proportion of water uptake gradually decreased with increasing depth. After rainfall, the sources of plant water uptake differed slightly between the two soil layers. The plants in non-subsidence and subsidence areas dominantly extracted soil water at depths greater than 10 cm and 20 cm, respectively. The root system in the subsidence area was more developed than that in the non-subsidence area. Plant water uptake was primarily influenced by the spatial distribution of roots, as well as the post-rainfall water distribution, regardless of whether they were in the subsidence area or not. Although land subsidence affected soil water transport, the water uptake pattern of Stipa bungeana Trin. was similar before and after rainfall, indicating the adaptive growth of plants through their roots in the subsidence area. The high adaptability of herbs such as Stipa bungeana Trin. makes them a viable option for vegetation restoration in subsidence areas. This study has significant implications for evaluating plant–water relationships in subsidence areas due to coal mining, thereby providing a fundamental basis and valuable reference for ecological restoration and management strategies within such affected regions.

Water Use Efficiency in Young Citrus Trees on Metalized UV Reflective Mulch Compared to Bare Ground

A precise estimation of plant water use is crucial for efficient irrigation management and understanding of plant–water interactions. Metalized-polyethylene mulch as a ground cover, combined with irrigation management, can improve water and fertilizer use, efficiency growth, and yield of young citrus trees, compared to bare ground. Thus, a study was undertaken to (i) compare daily water use, using the stem heat balance (SHB) method on ≤4-year-old citrus trees using three irrigation methods, and (ii) to determine soil moisture content, as well as total available soil water (TASW) in the irrigated zone. Three irrigation methods, regulated deficit irrigation (RDI), conventional drip irrigation (CD), and microsprinkler irrigation (MS), were applied on two sandy soils in central and southwest Florida with treatments further split between trees grown on 2.4 m mulched beds (M) and bare ground (NM) to form a factorial design. Measurements included sap flow, canopy size, leaf area index (LAI) and soil moisture. The result of this study shows greater values for the trunk cross-sectional area, canopy volume and LAI for both mulch treatments, in comparison to bare ground treatments. The sap flow data suggest that RDI resulted in higher water use than both CD and MS. The hourly sap flow was 120, 99 and 163% greater in M-RDI than M-CD, NM-CD and NM-MS, respectively. Mulched ground cover showed a higher soil moisture average at all soil layers (8-, 15- and 45-cm depth). For instance, the mulched ground cover showed higher soil moisture (37%) at a 15 cm depth at the Entisol site, followed by 30% at a 45 cm depth and 25.3% at depth 45 cm for the Spodosol site. The TASW values varied between 100 to 136% for both mulch and bare ground treatments. The irrigation systems used showed water contents close to field capacity, indicating that water was not limiting despite the different irrigation schedules. The high-water uptake is ascribed to frequent irrigation applications and pulses, and improved water distribution in the irrigated zone as a result of the mulch. These findings demonstrate the potential of metalized-polyethylene mulch and regulated drip irrigation to enhance water use efficiency.

Impacts of Climate Change on the Plant Water Interactions

Climate change has an impact on ecosystem structure and function globally by altering the relationships between plants and soil organisms. Despite the fact that water is the most plentiful molecule on Earth's surface, water scarcity is the element that most severely limits global terrestrial plant production. Little is known about the climatic factors that drive phenological responses to climate change, and less attention has been paid to the fact that phenology is also responsive to other climatic. The aim of this study was to assess the impacts of climate change on plant water interactions. This study was guided by the specific objectives, which included examining the relationship between climate change and plant function; finding out the impacts of climate change on plant water interactions; and assessing how plants handle water scarcity. It was found that there was a linkage between climate change and plant function. The evaporation of water molecules from the outer surfaces of the mesophyll cells initiates the upward transpiration pull in the leaves, and respiring starches and sugars are created during photosynthetic processes using sunlight energy. Climate change enhanced the most enormous movement of species that has occurred without direct human intervention. It was also found that precipitation was a key driver of phenological changes in desert ecosystems. It was also found that drought was one of the most significant biotic challenges faced by plants, with considerable genetic variation in water deficit responses. There is a need for research on climate change to ease biodiversity conservation. Keywords: Climate change, Plant water interactions, Plant, Water DOI: 10.7176/JRDM/87-01 Publication date: September 30 th 2022

Seasonal variations in water flux compositions controlled by leaf development: isotopic insights at the canopy-atmosphere interface.

Water-stable isotopes provide a valuable tool for tracing plant-water interactions, particularly evapotranspiration (ET) partitioning and leaf water dynamics at the plant-atmosphere interface. However, process-based investigations of plant/leaf development and the associated isotopic dynamics of water fluxes involving isotope enrichment at plant-atmosphere interfaces at the ecosystem scale remain challenging. In this study, in situ isotopic measurements and tracer-aided models were used to study the dynamic interactions between vegetation growth and the isotopic dynamics of water fluxes (ET, soil evaporation, and transpiration) involving isotope enrichment in canopy leaves in a multispecies grassland ecosystem. The day-to-day variations in the isotopic compositions of ET flux were mainly controlled by plant growth, which could be explained by the significant logarithmic relationship determined between the leaf area index and transpiration fraction. Leaf development promoted a significant increase in the isotopic composition of ET and led to a slight decrease in the isotopic composition of water in canopy leaves. The transpiration (evaporation) isoflux acted to increase (decrease) the δ18O of water vapor, and the total isoflux impacts depended on the seasonal tradeoffs between transpiration and evaporation. The isotopic evidence in ET fluxes demonstrates the biotic controls on day-to-day variations in water/energy flux partitioning through transpiration activity. This study emphasizes that stable isotopes of hydrogen and oxygen are effective tools for quantitative evaluations of the hydrological component partitioning of ecosystems and plant-climate interactions.

Dynamic Crop Models and Remote Sensing Irrigation Decision Support Systems: A Review of Water Stress Concepts for Improved Estimation of Water Requirements

Novel technologies for estimating crop water needs include mainly remote sensing evapotranspiration estimates and decision support systems (DSS) for irrigation scheduling. This work provides several examples of these approaches, that have been adjusted and modified over the years to provide a better representation of the soil–plant–atmosphere continuum and overcome their limitations. Dynamic crop simulation models synthetize in a formal way the relevant knowledge on the causal relationships between agroecosystem components. Among these, plant–water–soil relationships, water stress and its effects on crop growth and development. Crop models can be categorized into (i) water-driven and (ii) radiation-driven, depending on the main variable governing crop growth. Water stress is calculated starting from (i) soil water content or (ii) transpiration deficit. The stress affects relevant features of plant growth and development in a similar way in most models: leaf expansion is the most sensitive process and is usually not considered when planning irrigation, even though prolonged water stress during canopy development can consistently reduce light interception by leaves; stomatal closure reduces transpiration, directly affecting dry matter accumulation and therefore being of paramount importance for irrigation scheduling; senescence rate can also be increased by severe water stress. The mechanistic concepts of crop models can be used to improve existing simpler methods currently integrated in irrigation management DSS, provide continuous simulations of crop and water dynamics over time and set predictions of future plant–water interactions. Crop models can also be used as a platform for integrating information from various sources (e.g., with data assimilation) into process-based simulations.

&amp;lt;i&amp;gt;tran&amp;lt;/i&amp;gt;-SAS v1.0: a numerical model to compute catchment-scale hydrologic transport using StorAge Selection functions

Abstract. This paper presents the “tran-SAS” package, which includes a set of codes to model solute transport and water residence times through a hydrological system. The model is based on a catchment-scale approach that aims at reproducing the integrated response of the system at one of its outlets. The codes are implemented in MATLAB and are meant to be easy to edit, so that users with minimal programming knowledge can adapt them to the desired application. The problem of large-scale solute transport has both theoretical and practical implications. On the one side, the ability to represent the ensemble of water flow trajectories through a heterogeneous system helps unraveling streamflow generation processes and allows us to make inferences on plant–water interactions. On the other side, transport models are a practical tool that can be used to estimate the persistence of solutes in the environment. The core of the package is based on the implementation of an age master equation (ME), which is solved using general StorAge Selection (SAS) functions. The age ME is first converted into a set of ordinary differential equations, each addressing the transport of an individual precipitation input through the catchment, and then it is discretized using an explicit numerical scheme. Results show that the implementation is efficient and allows the model to run in short times. The numerical accuracy is critically evaluated and it is shown to be satisfactory in most cases of hydrologic interest. Additionally, a higher-order implementation is provided within the package to evaluate and, if necessary, to improve the numerical accuracy of the results. The codes can be used to model streamflow age and solute concentration, but a number of additional outputs can be obtained by editing the codes to further advance the ability to understand and model catchment transport processes.

Nitrogen dynamics vary across hydrologic gradients and by forest community composition in the perhumid coastal temperate rainforest of southeast Alaska

Nitrogen (N) limitation constrains plant growth, but complex interactions among species and ecosystems hinder our ability to identify primary drivers of N availability. Hydrologic, biogeochemical, and ecological processes interact spatially and temporally, requiring measurements of N across diverse ecosystem types and as a function of both site conditions and vegetation composition. We measured initial exchangeable and mineralized N along a hydrologic gradient in the Alaskan perhumid coastal temperate rainforest to test a conceptual model of linkages between N availability and landscape, hydrologic, and ecosystem characteristics in temperate forests. Mineralization was closely associated with inorganic N concentrations. Inorganic N as NH4+ generally increased with increasing depth to groundwater but was strongly determined by plant–water interactions. Exchangeable and mineralized N were closely linked to tree species, forest biomass, and hydrologic regime regardless of ecosystem type. The emergence of tree species as indicators of N cycling highlights the effect that species have on nutrient dynamics, while the trend of increasing inorganic N with increasing soil saturation points to the role of hydrology in driving N availability. Our research quantified N dynamics for an understudied, yet critical, system and provides a framework for exploring feedbacks among soil saturation, forest composition, and nutrient cycling in temperate forests.

Modeling plant–water interactions: an ecohydrological overview from the cell to the global scale

Vegetation and the water cycles are inherently coupled across a wide range of spatial and temporal scales. Water availability interacts with plant ecophysiology and controls vegetation functioning. Concurrently, vegetation has direct and indirect effects on energy, water, carbon, and nutrient cycles. To better understand and model plant–water interactions, highly interdisciplinary approaches are required. We present an overview of the main processes and relevant interactions between water and plants across a range of spatial scales, from the cell level of leaves, where stomatal controls occur, to drought stress at the level of a single tree, to the integrating scales of a watershed, region, and the globe. A review of process representations in models at different scales is presented. More specifically, three main model families are identified: (1) models of plant hydraulics that mechanistically simulate stomatal controls and/or water transport at the tree level; (2) ecohydrological models that simulate plot‐ to catchment‐scale water, energy, and carbon fluxes; and (3) terrestrial biosphere models that simulate carbon, water, and nutrient dynamics at the regional and global scales and address feedback between Earth's vegetation and the climate system. We identify special features and similarities across the model families. Examples of where plant–water interactions are especially important and have led to key scientific findings are also highlighted. Finally, we discuss the various data sources that are currently available to force and validate existing models, and we present perspectives on the evolution of the field. WIREs Water 2016, 3:327–368. doi: 10.1002/wat2.1125This article is categorized under: Water and Life &gt; Nature of Freshwater Ecosystems Science of Water &gt; Hydrological Processes

Varietal differences in growth and Cs allocation of blackgram (Vigna mungo) under water stress

Plant uptake and distribution of radioactive caesium (137Cs) was examined in an effort to determine how plant-water interactions differ between two blackgram plant varieties with different salt tolerance. Salt-tolerant U Taung-2 (BT) and the salt-sensitive variety Mutpe Khaing To (BS) were grown in pots filled with 137Cs-contaminated soil obtained from Nihonmatsu, Fukushima, Japan. The average soil 137Cs concentration was 1084Bqkg−1, and the soil type comprised sandy clay loam, where the sand: silt: clay proportion was 62:18:20. After growing for 15 days in a temperature-controlled growth chamber, plants were subjected to drought stress conditions by addition of either 10 or 20% polyethylene glycol (PEG 6000) to the soil to reduce the osmotic potential of the soil, or to field capacity conditions (0% PEG).Analysis of the growth traits and water relations revealed the different strategies employed by the two blackgram varieties under water stress conditions. No differences were observed among the two varieties under field capacity conditions. However, under both drought stress conditions (10 or 20% PEG), the reduction in total leaf area, total biomass and plant growth analysis parameters, in addition to the relative water content, were higher in BS than in BT plants. Both plant varieties exhibited lower 137Cs concentrations in the leaves, shoots and roots under drought stress conditions compared to plants subjected to field capacity conditions. Under drought stress conditions, BT plants showed uptake and translocation of 137Cs from the roots to shoots and leaves, while this activity was seriously limited in BS plants, and especially in the leaf portion of BS plants treated with 20% PEG. In BT plants, potassium moved more freely than Cs from roots to the aerial parts of the plant under water stress conditions, while this was not the case in BS plants. Examination of the hydraulic conductivity showed a positive correlation with the 137Cs concentration in leaf and stem. Our results showed that the accumulation and distribution patterns of 137Cs among part of the blackgram tissues were dependent on plant growth performance, water movement pathways, and selective absorption.

Training hydrologists to be ecohydrologists: a &amp;quot;how-you-can-do-it&amp;quot; example leveraging an active learning environment for studying plant–water interaction

Abstract. Structuring an education strategy capable of addressing the various spheres of ecohydrology is difficult due to the inter-disciplinary and cross-disciplinary nature and general breadth of this emergent field. Clearly, there is a need for such strategies to accommodate more progressive educational concepts while highlighting a skills-based education. To demonstrate a possible way to develop courses that include such concepts, we offer a case-study or a potential "how-you-can-do-it" example from a recent course set in an ecohydrological context co-taught by teachers from Stockholm University and Cornell University at Stockholm University's Navarino Environmental Observatory (NEO) in Costa Navarino, Greece. This course focused on introducing hydrology Master's students to some of the central concepts of ecohydrology, while at the same time supplying process-based understanding relevant for characterizing evapotranspiration. As such, the main goal of the course was to explore some of the central theories in ecohydrology and their connection to plant–water interactions and the water cycle in a semiarid environment. While this course is still in its infancy with regards to addressing some of the more in-depth aspects of ecohydrology, it does provide a relevant basis with an initial emphasis on the more physical concepts of ecohydrology from which to build towards the more physiological concepts (e.g., unique plant adaptations to water availability or differences in water use between native plants and irrigated vegetation). In addition to presenting this roadmap for ecohydrology course development, we explore the utility and effectiveness of adopting active teaching and learning strategies drawing from the suite of learn-by-doing, hands-on, and inquiry-based techniques in such a course. We test a potential gradient of "activeness" across a sequence of three teaching and learning activities. Our results indicate that there was a clear advantage for utilizing active learning with a preference among the students towards the more "active" techniques. This demonstrates the added value of incorporating even the simplest active learning approaches in our ecohydrology (or general) teaching.

Assessing the Role of Parameter and Input Uncertainty in Ecohydrologic Modeling: Implications for a Semi-arid and Urbanizing Coastal California Catchment

Ecohydrologic models are a key tool in understanding plant–water interactions and their vulnerability to environmental change. Although implications of uncertainty in these models are often assessed within a strictly hydrologic context (for example, runoff modeling), the implications of uncertainty for estimation of vegetation water use are less frequently considered. We assess the influence of commonly used model parameters and inputs on predictions of catchment-scale evapotranspiration (ET) and runoff. By clarifying the implications of uncertainty, we identify strategies for insuring that the quality of data used to drive models is considered in interpretation of model predictions. Our assessment also provides insight into unique features of semi-arid, urbanizing watersheds that shape ET patterns. We consider four sources of uncertainty: soil parameters, irrigation inputs, and spatial extrapolation of both point precipitation and air temperature for an urbanizing, semi-arid coastal catchment in Santa Barbara, CA. Our results highlight a seasonal transition from soil parameters to irrigation inputs as key controls on ET. Both ET and runoff show substantial sensitivity to uncertainty in soil parameters, even after parameters have been calibrated against observed streamflow. Sensitivity to uncertainty in precipitation manifested primarily in winter runoff predictions, whereas sensitivity to irrigation manifested exclusively in modeled summer ET. Neither ET nor runoff was highly sensitive to uncertainty in spatial interpolation of temperature. Results argue that efforts to improve ecohydrologic modeling of vegetation water use and associated water-limited ecological processes in these semi-arid regions should focus on improving estimates of anthropogenic outdoor water use and explicit accounting of soil parameter uncertainty.

Ecohydrology and Fish-Passage Engineering: Legacy of Denil and the Call for a More Inclusive Paradigm

Ecohydrology and Fish-Passage Engineering: Legacy of Denil and the Call for a More Inclusive Paradigm

Effects of Biofertilizers on Maize and Sunflower Seedlings under Cadmium Stress

Application of various alternative nutrient supplies can partly be substituted by chemical fertilizers, resulting in economical use with less environmental strains. Biofertilizers containing living microorganisms promote nutrition uptake, but still there are questions regarding their application under stress conditions. One of the main abiotic factors that can induce stress is contamination of soils with toxic elements. In the course of intensive plant-growth conditions, considerable quantities of basic cations are removed from the soil, resulting in acidification and thereby enhancing the uptake of heavy metals by plants. Cadmium (Cd) toxicity is a major problem affecting crop productivity worldwide. The presence of Cd in the rhizosphere can cause stress responses and alteration in many physiological processes, including nitrogen metabolism, photosynthesis, carbohydrate metabolism, sulfate assimilation, and plant–water interactions. Once in the plant, Cd can enter the food chain, causing public health problems. The aim of our work was to investigate the effects of biofertilizers on plant production and nutrient uptake in some Cd-contaminated soils. Our results revealed that Cd accumulated primarily in the roots and transport to the shoots was rather low; however, there were differences between the two plants species. Plant uptake by sunflower was greater than by maize, and sunflower appeared to be more stress tolerant of Cd than maize. With the use of the bacterium-containing biofertilizer, the toxic effect of Cd was moderated.

Rhizofiltration of a Heavy Metal (Lead) Containing Wastewater Using the Wetland Plant Carex pendula

AbstractRhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant–water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non‐hydroponics experiment to mimic the real wetland conditions more closely.

Stochastic Dynamics of Plant-Water Interactions

Describing water flow from soil through plants to the atmosphere remains a formidable scientific challenge despite years of research. This challenge is not surprising given the high dimensionality and degree of nonlinearity of the soil-plant system, which evolves in space and time according to complex internal physical, chemical, and biological laws forced by external hydroclimatic variability. Although rigorous microscopic laws for this system still await development, some progress can be made on the formulation of macroscopic laws that upscale known submacroscopic processes and use surrogate stochasticity to preserve the probabilistic and spectral information content of the high dimensional system. The external hydroclimatic forcing is inherently intermittent with variability across all scales, thereby precluding the use of standard approximations employed in analysis of stochastic processes (e.g., small noise perturbations). Examples are provided to show how superposition of stochasticity at multiple space-time scales shapes plant-water interactions.

The Life and Scientific Contributions of Lyman J. Briggs

Lyman J. Briggs (1874–1963), an early twentieth century physicist at the U.S. Department of Agriculture (USDA), made many significant contributions to our understanding of soil-water and plant-water interactions. He began his career at the Bureau of Soils (BOS) in 1896. At age 23, Briggs published (1897) a description of the roles of surface tension and gravity in determining the state of static soil moisture. Concepts he presented remain central to this subject more than 100 yr later. With J.W. McLane, Briggs developed the “moisture equivalent” concept (a precursor to the idea of field capacity) and a centrifuge apparatus for measuring it. Briggs left the BOS at the end of 1905, under pressure from Milton Whitney, and moved to the Bureau of Plant Industry. Briggs' multi-state experiments with H.L. Shantz on water-use efficiencies showed that in a climate like that of the Great Plains, plants use water more productively in the cooler north than in the warmer south. In 1920, he moved from the USDA to the National Bureau of Standards (NBS), rising to Director in 1933. Among his other contributions to the American scientific community was his leadership, beginning in 1939, of a top secret committee that evolved into the Manhattan Project to develop an atomic bomb during World War II. A life-long baseball fan, Briggs at age 84, studied the speed, spin, and deflection of the curve ball, aided by manager Cookie Lavagetto and the pitching staff of the Washington Senators; he published these findings in a paper in the American Journal of Physics in 1959.

The Life and Scientific Contributions of Lyman J. Briggs

Lyman J. Briggs (1874–1963), an early twentieth century physicist at the U.S. Department of Agriculture (USDA), made many significant contributions to our understanding of soil-water and plant-water interactions. He began his career at the Bureau of Soils (BOS) in 1896. At age 23, Briggs published (1897) a description of the roles of surface tension and gravity in determining the state of static soil moisture. Concepts he presented remain central to this subject more than 100 yr later. With J.W. McLane, Briggs developed the “moisture equivalent” concept (a precursor to the idea of field capacity) and a centrifuge apparatus for measuring it. Briggs left the BOS at the end of 1905, under pressure from Milton Whitney, and moved to the Bureau of Plant Industry. Briggs' multi-state experiments with H.L. Shantz on water-use efficiencies showed that in a climate like that of the Great Plains, plants use water more productively in the cooler north than in the warmer south. In 1920, he moved from the USDA to the National Bureau of Standards (NBS), rising to Director in 1933. Among his other contributions to the American scientific community was his leadership, beginning in 1939, of a top secret committee that evolved into the Manhattan Project to develop an atomic bomb during World War II. A life-long baseball fan, Briggs at age 84, studied the speed, spin, and deflection of the curve ball, aided by manager Cookie Lavagetto and the pitching staff of the Washington Senators; he published these findings in a paper in the American Journal of Physics in 1959.

Is bigger better in plants? The hydraulic costs of increasing size in trees

Three new studies suggest that tall trees experience increased hydraulic stress in drawing water from the soil into their canopies. They adjust to this by various homeostatic mechanisms, such as reducing the leaf area/conducting stem ratio. These mechanisms partly mask the hydraulic consequences of increased tree height in some measures of plant–water interactions, and have implications for the hydraulic limitations hypothesis and the fractal networks transport hypothesis.

Plants for environmental studies

The Effects of Ultra Violet-B Radiation on Higher Plants, B. Greenberg, M.I. Wilson, X.-D. Huang, C.L. Duxbury, K.E. Gerhardt, and R.W. Gensemer Radiation Effects on Plants, R.W. Holst and D.J. Nagel Plant-Water Interactions, J.L. Hatfield Plant Activation of Environmental Agents: The Utility of the Plant Cell/Microbe Coincubation Assay, M.J. Plewa, K.-Y. Seo, Y.-H. Ju, S.R. Smith, and E.D. Wagner Statistical Methods in Plant Environmental Studies, M. Ritter Water Quality and Aquatic Plants, M.A. Lewis and W. Wang Algal Indicators of Aquatic Ecosystem Conditions and Change, P.V. McCormick and J. Cairns Photosynthetic Electron Transport as a Bioassay, J. Gemel, B. Waters-Earhart, M.R. Ellersieck, A. Asfaw, G.F. Krause, V. Puri, and W.R. Lower Laboratory Bioassays with Microalgae, N. Nyholm and H.G. Peterson Aquatic Plant Communities for Impact Monitoring and Assessment, B.H. Hill Allium Test for Screening Chemicals Evaluation of Cytological Parameters, G. Fiskesjo The Use of Vascular Plants as Field Biomonitors, R.L. Powell Metal Accumulation by Aquatic Macrophytes, W. Wang and M.A. Lewis Bioaccumulation of Xenobiotic Organic Chemicals by Terrestrial Plants, O.J. Schwartz and L.W. Jones Uptake of Polycyclic Aromatic Hydrocarbons by Vegetation: A Review of Experimental Methods, T.A. Anderson, A.M. Hoylman, N.T. Edwards, and B. Walton Plant Uptake and Metabolism Polychlorinated Biphenyls (PCBs), R.K. Puri, Y. Qiuping, S. Kapila, W.R. Lower, and V. Puri Selection of Phytotoxicity Tests for Use in Ecological Risk Assessments, L.A. Kapustka Index