Andrea Carminati

• Professor (Full) at ETH Zurich

Background and Aims Biophysicochemical soil properties in the rhizosheath are pivotal for crop yields and drive organic carbon cycling in agricultural soils. Yet, it remains uncertain how moderate soil drought may alter and interfere with rhizosheath properties in diverse soil types, and whether specific rhizosheath traits benefit crop yields under...

Drought impacts trees in varied temporal and spatial patterns, suggesting that heterogeneity of below‐ground water stores influences the fate of trees under water stress. Karst ecosystems rely on shallow soil overlying bedrock that can store available water in primary pores. A contribution of rock moisture to tree water status has been previously d...

Tree water status is mainly determined by the amount of water taken up from roots and lost through leaves by transpiration. Variations in transpiration and stomatal conductance, are often related to atmospheric conditions and leaf water potential. Yet, few experimental datasets exist, that enable relating leaf water potential and transpiration dyna...

Background and Aims Mucilage has been hypothesized to soften the gradients in matric potential at the root-soil interface, hereby facilitating root water uptake in dry soils and maintaining transpiration with a moderate decline in leaf water potential. So far, this hypothesis has been tested only through simplified experiments and numerical simulat...

Low soil moisture and high vapour pressure deficit (VPD) cause plant water stress and lead to a variety of drought responses, including a reduction in transpiration and photosynthesis1,2. When soils dry below critical soil moisture thresholds, ecosystems transition from energy to water limitation as stomata close to alleviate water stress3,4. Howev...

Gas exchange in the soil is determined by the size and connectivity of air‐filled pores. Root mucilage reduces air‐filled pore connectivity and thus gas diffusivity. It is unclear to what extent mucilage affects soil pore connectivity and tortuosity. The aim of this study was to gain a better understanding of gas diffusion processes in the rhizosph...

Information on soil water potential is essential to assessing the soil moisture state, to prevent soil compaction in weak soils, and to optimize crop management. When there is a lack of direct measurements, the soil water potential values must be deduced from soil water content dynamics that can be monitored at the plot scale or obtained at a large...

The close interconnection of plants with rhizosphere- and root-associated microorganisms is well recognized, and high expectations are raised for considering their symbioses in the breeding of future crop varieties. However, it is unclear how consistently plant-mediated selection, a potential target in crop breeding, influences microbiome members c...

In an increasingly dry environment, it is crucial to understand how tree species use soil water and cope with drought. However, there is still a knowledge gap regarding the relationships between species-specific stomatal behaviour, spatial root distribution, and root water uptake (RWU) dynamics. Our study aimed to investigate above- and below-groun...

Background And Aims Root hair emergence is affected by heterogeneities in water availability in the growth medium. Root hairs preferentially emerge into air, whereas their emergence into water is inhibited. Yet, these results were based either on destructive methods or on roots grown on an agar-air interface. Additionally, there is a lack of knowle...

Many efforts to improve crop yields in water-limited environments have been directed towards identifying genotypes capable of restricting their transpiration rate (TR) at high vapor pressure deficit (VPD). This has proven challenging due to the dependence of the TR-VPD relationship on environmental conditions. In this context, however, the impact o...

Plant water uptake from the soil is a crucial element of the global hydrological cycle and essential for vegetation drought resilience. Yet, knowledge of how the distribution of water uptake depth (WUD) varies across species, climates, and seasons is scarce relative to our knowledge of aboveground plant functions. With a global literature review, w...

Background and Aims Climate change is happening and causing severe impact on the sustainability of agroecosystems. We argue that many of the abiotic stresses associated with climate change will be most acutely perceived by the plant at the root-soil interface and are likely to be mitigated at this globally important interface. In this review we wil...

A holistic understanding of plant strategies to acquire soil resources is pivotal in achieving sustainable food security. However, we lack knowledge about variety-specific root and rhizosphere traits for resource acquisition, their plasticity and adaptation to drought. We conducted a greenhouse experiment to phenotype root and rhizosphere traits (m...

Information on soil water potential is essential to assess soil moisture state, to prevent soil compaction in weak soils, and to optimize crop management. In lack of direct measurements, the soil water potential values must be deduced from soil water content dynamics that can be monitored at plot scale or obtained at larger scale from remote sensin...

Biophysicochemical rhizosheath properties play a vital role in plant drought adaptation. However, their integration into the framework of plant drought response is hampered by incomplete mechanistic understanding of their drought responsiveness and unknown linkage to intraspecific plant–soil drought reactions. Thirty‐eight Zea mays varieties were g...

The effect of environmental conditions, species-specific plant hydraulic traits and root water uptake dynamics on stomatal conductance are still uncertain. We monitored water potentials and water fluxes in soils, roots, stems, and leaves of beech and spruce to further our understanding of the water status in these segments along the soil-plant hydr...

Water will be a major limitation to food production in the 21st century, and drought issues already prevail in many parts of the world. Finding solutions to ensure that farmers harvest profitable crops, and secure food supplies for families and feed for animals that will provide for them through to the next season are urgent necessities. The Interd...

Terrestrial water fluxes are dominated by transpiration, with stomata exerting an important control by regulating transpirational water loss. Transpiration and stomatal conductance are in turn constrained by the hydraulic properties of the soil-plant-atmosphere continuum, thus providing a link between the physics of water flow (soil-plant hydraulic...

Drought is a major threat to food security worldwide. Recently, the root-soil interface has emerged as a major site of hydraulic resistance during water stress. Here, we review the impact of soil drying on whole plant hydraulics and discuss mechanisms by which plants can adapt by modifying the properties of the rhizosphere either directly or throug...

The effect of root hairs on water uptake remains controversial. In particular, the key root hair and soil parameters that determine their importance have been elusive. We grew maize plants (Zea mays) in microcosms and scanned them using synchrotron‐based X‐ray computed microtomography. By means of image‐based modelling, we investigated the paramete...

The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit, VPD) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil...

Addition of microplastics (MP) to soil has the potential to increase soil water repellency. However, coating of MP with soil abundant substances e.g., iron compounds, can reduce this effect. Here, we tested if pre-coating or in situ coating of MP with ferrihydrite (Fh) reduces soil water repellency. We applied hotspots of pristine and coated MP (20...

Das Kapitel: Geschichte der Bodenphysik und ihre Entwicklung in den verschiedenen Teilbereichen behandelt die Entwicklung in den letzten Jahrzehnten des 20. und im beginnenden 21. Jahrhundert. Zu Beginn werden die Prozesse der Gefügeentwicklung und deren Detektion sowie die damit einhergehenden Modellierungsansätze der Wasserflüsse analysiert, gefo...

Background Few studies have evaluated the effect of drought on the morpho‐physiological characteristics of African C4 grasses. We investigated how drought affects leaf gas exchange characteristics, biomass partitioning, and water use efficiencies of Enteropogon macrostachyus and Cenchrus ciliaris. Methods The grasses were grown in a controlled env...

Intensively managed open croplands are highly productive but often have deleterious environmental impacts. Temperate agroforestry potentially improves ecosystem functions, although comprehensive analysis is lacking. Here, we measured primary data on 47 indicators of seven ecosystem functions in croplands and 16 indicators of four ecosystem function...

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The efficiency‐safety tradeoff has been thoroughly investigated in plants, especially concerning their capacity to transport water and avoid embolism. Stomatal regulation is a vital plant behavior to respond to soil and atmospheric water limitation. Recently, a stomatal efficiency‐safety tradeoff was reported where plants with higher maximum stomat...

Background and Aim Stomatal regulation allows plants to promptly respond to water stress. However, our understanding of the impact of above and belowground hydraulic traits on stomatal regulation remains incomplete. The objective of this study was to investigate how key plant hydraulic traits impact transpiration of maize during soil drying. We hyp...

When soils dry, water flow and nutrient diffusion cease as the hydraulic microenvironments vital for soil life become fragmented. To delay soil drying locally and related adverse effects, bacteria and plants modify their surroundings by releasing extracellular polymeric substances (EPS). As a result, the physical properties of hotspots like biologi...

Aims Although soil water deficit is the primary constraint on transpiration globally, the mechanisms by which soil drying and soil properties impact transpiration and stomatal regulation remain elusive. This work aimed to investigate how soil textures and vapor pressure deficit (VPD) impact the relationship between transpiration rate, canopy conduc...

Plants offer some of the most elegant applications of soft matter principles in Nature. Understanding the interplay between chemistry, physics, biology, and fluid mechanics is critical to forecast plant behaviour, which is necessary for agriculture and disease management. It also provides inspiration for novel engineering applications. Starting wit...

Background and aims Impact of drought on crop growth depends on soil and root hydraulic properties that determine the access of plant roots to soil water. Root hairs may increase the accessible water pool but their effect depends on soil hydraulic properties and adaptions of root systems to drought. These adaptions are difficult to investigate in p...

Root hairs and soil water content are crucial in controlling the release and diffusion of root exudates and shaping profiles of biochemical properties in the rhizosphere. But whether root hairs can offset the negative impacts of drought on microbial activity remains unknown. Soil zymography, ¹⁴C imaging and neutron radiography were combined to iden...

Purpose Although the coordination between stomatal closure and aboveground hydraulics has extensively been studied, our understanding of the impact of belowground hydraulics on stomatal regulation remains incomplete. Here, we investigated whether and how the water use of maize (Zea mays L.) varied under hydraulically contrasting soil textures. Our...

Soil hydrological processes (SHP) support ecosystems, modulate the impact of climate change on terrestrial systems and control feedback mechanisms between water, energy and biogeochemical cycles. However, land-use changes and extreme events are increasingly impacting these processes. In this Review, we describe SHP across scales and examine their l...

Soils are considered the largest sink of microplastic (MP) in terrestrial ecosystems. However, little is known about the implications of MP on soil physical properties. We hypothesize that low wettability of MP induces soil water repellency, depending on MP content and size of MP and soil particles. We quantified wettability of mixtures of MP and s...

Mucilage is a gelatinous high-molecular-weight substance produced by almost all plants, serving numerous functions for plants and soil. To date, research has mainly focused on the hydraulic and physical functions of mucilage in the rhizosphere. Studies on the relevance of mucilage as a microbial habitat are scarce. Microbial research has largely fo...

Salinity and soil drying are expected to induce salt accumulation at the root-soil interface of transpiring plants. However, the consequences of this on the relationship between transpiration rate (E) and leaf xylem water potential (ψleaf-x) are yet to be quantified. Here, we used a non-invasive root pressure chamber to measure the E(ψleaf-x) relat...

Aims Root hairs are important for uptake, especially for nutrients with low mobility in soils with high sorption capacity. Mutants with defective root hairs are expected to have lower nutrient uptake, unless they compensate with more root growth. Since root hairs can also contribute to the plant's water uptake their importance could change over the...

Soil water repellency is traditionally expressed as contact angle (CA) and measured destructively on exposed surfaces or derived from flow behavior or measured forces. These approaches cannot map local heterogeneities in CA, which typically exist in intact soil. Here, we explore the potential and limitations of in situ measurements of three‐dimensi...

Background and aims: Impact of drought on crop growth depends on soil and root hydraulic properties that determine the acces of plant roots to soil water. Root hairs may increase the accessible water pool but their effect depends on soil hydraulic properties and adaptions of root systems to drought. These adaptions are difficult to investigate in p...

Root hairs improve plant access to soil resources, especially under edaphic stress (Singh Gahoonia & Nielsen, 2004; Marin et al., 2020; Wissuwa & Kant, 2021). While root shrinkage and the formation of cortical lacunae limit the continuity of the liquid phase at the root-soil interface (Nobel & Cui, 1992; Carminati et al., 2009; Cuneo et al., 2016),...

Purpose Simultaneously interacting rhizosphere processes determine emergent plant behaviour, including growth, transpiration, nutrient uptake, soil carbon storage and transformation by microorganisms. However, these processes occur on multiple scales, challenging modelling of rhizosphere and plant behaviour. Current advances in modelling and experi...

Aims: Root hairs are important for uptake, especially for nutrients with low mobility in soils with high sorption capacity. Yet, this has rarely been demonstrated in the field during a whole growing season. Mutants with defective root hairs are expected to have lower nutrient uptake, unless they compensate with more root growth. Since root hairs ca...

Soil drying is a limiting factor for crop production worldwide. Yet, it is not clear how soil drying impacts water uptake across different soils, species, and root phenotypes. Here we ask: 1) what root phenotypes improve the water use from drying soils? and 2) what root hydraulic properties impact water flow across the soil-plant continuum? The mai...

Mucilage is a gelatinous high-molecular-weight substance produced by almost all plants, serving numerous functions for plant and soil. To date, research has mainly focused on hydraulic and physical functions of mucilage in the rhizosphere. Studies on the relevance of mucilage as a microbial habitat are scarce. Extracellular polymeric substances (EP...

Background and Aims Stomatal closure allows plants to promptly respond to water shortage. Although the coordination between stomatal regulation, leaf and xylem hydraulics has been extensively investigated, the impact of belowground hydraulics on stomatal regulation remains unknown. Methods We used a novel root pressure chamber to measure, during s...

Plant roots and bacteria alter the soil physical properties by releasing polymeric blends into the soil pore space (e.g., extracellular polymeric substances and mucilage). The physical mechanisms by which these substances interact with the soil matrix and alter the spatial configuration of the liquid phase and the related hydraulic properties remai...

Understanding stomatal regulation during drought is essential to correctly predict vegetation‐atmosphere fluxes. Stomatal optimization models posit that stomata maximize the carbon gain relative to a penalty caused by water loss, such as xylem cavitation. However, a mechanism that allows the stomata to behave optimally is unknown. Here, we introduc...

Plants stimulate microbial enzyme production in the rhizosphere, regulating soil organic matter decomposition and nutrient cycling. The availability of labile organic compounds (i.e. exudates) and water is the main prerequisite for such microbial activity and enzyme production, thus shaping the rhizosphere. Root morphology (i.e., root hairs) and ex...

Purpose Simultaneously interacting small-scale rhizosphere processes determine emergent plant-scale behaviour, including growth, transpiration, nutrient uptake, soil carbon storage and transformation by microorganisms. Current advances in modelling and experimental methods open the path to unravel and link those processes. Methods We present a seri...

Although the role of root hairs (RHs) in nutrient uptake is well documented, their role in water uptake and drought tolerance remains controversial. Maize (Zea mays) wild-type and its hair-defective mutant (rth3) were grown in two contrasting soil textures (sand and loam). We used aroot pressure chamber to measure the relation between transpiration...

Aims Hydraulic redistribution (HR) enhances water resources for neighboring crops in silvopastoral agroforestry (AF). Here, we tested whether and to what extent water stressed shallow-rooted neighboring plants benefit from water redistributed by deep-rooted poplar plants. Methods We conducted trace experiments with deuterated water ( ² H 2 O) in g...

A soil–plant hydraulic model shows that the degree of isohydricity is constrained by below-ground hydraulic limitations and that the shape of plant water potential (WP) curve depends on soil hydraulics.

Simultaneous measurements of leaf water potential (ψleaf) and transpiration rate (E) for varying soil moistures (θ) is necessary to identify the hydraulic constrains on transpiration as the soil dries. However, continuous and accurate measurements of ψleaf in intact plants remain challenging. This work aims at describing a root pressure chamber sys...

Plants redistribute water from wet to dry soil layers through their roots, in the process called hydraulic redistribution. Although the relevance and occurrence of this process are well accepted, resolving the spatial distribution of hydraulic redistribution remains challenging. Here, we show how to use neutron radiography to quantify the rate of w...

The fundamental question as to what triggers stomatal closure during soil drying remains contentious. Thus, we urgently need to improve our understanding of stomatal response to water deficits in soil and atmosphere. Here, we investigated the role of soil-plant hydraulic conductance (Ksp) on transpiration (E) and stomata regulation. We used a root...

Microbes play an essential role in soil functioning including biogeochemical cycling and soil aggregate formation. Yet, a major challenge is to link microbes to higher trophic levels and assess consequences for soil functioning. Here, we aimed to assess how microbial consumers modify microbial community composition (PLFA markers), as well as C dyna...

Resilience of soils, i.e., their ability to maintain functions or recover after disturbance, is closely linked to the root-soil interface, the soil's power house. However, the limited observability of key processes at the root-soil interface has so far limited our understanding of how such resilience emerges. Here, we hypothesize that resilience em...

The current trend towards linking stomata regulation to plant hydraulics emphasizes the role of xylem vulnerability. Using a soil–plant hydraulic model, we show that xylem vulnerability does not trigger stomatal closure in medium-wet to dry soils and we propose that soil hydraulic conductivity loss is the primary driver of stomatal closure. This fi...

Phosphatases in soil are of great importance for plant P acquisition. It is hypothesized that root hairs increase rhizosphere phosphatase activity as they release enzymes into soil and stimulate microbial activity. To test the effect of root hairs on soil phosphatase activity, we grew barley (Hordeum vulgare ‘Pallas’) wild type and its root-hairle...

Water deficit is one of the primary limitations to crop production. Here, we review the role of root and rhizosphere hydraulic processes that affect the ability of a plant to extract water from the soil. Prominent features of rhizosphere hydraulic properties are: root shrinkage, alteration of pore geometry in the rhizosphere, effect of mucilage on...

Abstract. The formation and stabilisation of soil macro-aggregates protects soils from erosion, a major worldwide threat on soils. While the role of bacteria and fungi in soil aggregation is well established, how predators feeding on microbes modify soil aggregation has hardly been tested. Here, we studied how predators modulate the effect of micro...

More frequent and longer drought periods are predicted threatening agricultural yield. The capacity of soils to hold water is a highly important factor controlling drought stress intensity for plants. Biogenic amorphous silica (bASi) pools in soils are in the range of 0–6% and are suggested to help plants to resist drought. In agricultural soils, b...

More frequent and longer drought periods are predicted threatening agricultural yield. The capacity of soils to hold water is a highly important factor controlling drought stress intensity for plants. Biogenic amorphous silica (bASi) pools in soils are in the range of 0–6% and are suggested to help plants to resist drought. In agricultural soils, b...

Aims As soil dries, the loss of soil hydraulic conductivity limits water supply to the leaves, which is expected to generate a nonlinear relationship between leaf water potential (ψleaf) and transpiration (E). The effect of soil drying and root properties on ψleaf and E remains elusive. Methods We measured E and ψleaf of pearl millet for varying E...

In the original version of this article, equations 4 and 9 unfortunately contained errors

The relationship between leaf water potential, soil water potential, and transpiration depends on soil and plant hydraulics and stomata regulation. Recent concepts of stomatal response to soil drying relate stomatal regulation to plant hydraulics, neglecting the loss of soil hydraulic conductance around the roots. Our objective was to measure the e...