Andrea Carminati

Last Name

Carminati

First Name

Andrea

ORCID

0000-0001-7415-0480

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09732 - Carminati, Andrea / Carminati, Andrea

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Publications 1 - 10 of 81

Quantification of hydraulic redistribution in maize roots using neutron radiography
Hayat, Faisal; Zarebanadkouki, Mohsen; Ahmed, Mutez Ali; et al. (2020)
Vadose Zone Journal
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 water efflux from the roots to the soil. Maize (Zea mays L.) plants were grown in a sandy substrate 40 cm deep. Deuterated water (D2O) was injected in the bottom wet compartment, and its transport through the roots to the top dry soil was imaged using neutron radiography. A diffusion–convection model was used to simulate the transport of D2O in soil and root and inversely estimate the convective fluxes. Overnight, D2O appeared in nodal and lateral roots in the top compartment. By inverse modeling, we estimated an efflux from lateral roots into the dry soil equal to jr = 2.35 × 10−7 cm−1. A significant fraction of the redistributed water flew toward the tips of nodal roots (3.85 × 10−8 cm3 s−1 per root) to sustain their growth. The efflux from nodal roots depended on the roots’ length and growth rate. In summary, neutron imaging was successfully used to quantify hydraulic redistribution. A numerical model was needed to differentiate the effects of diffusion and convection. The highly resolved images showed the spatial heterogeneity of hydraulic redistribution.
Microhydrological Niches in Soils: How Mucilage and EPS Alter the Biophysical Properties of the Rhizosphere and Other Biological Hotspots
Benard, Pascal; Zarebanadkouki, Mohsen; Brax, Mathilde; et al. (2019)
Vadose Zone Journal
Plant roots and bacteria are capable of buffering erratic fluctuations of water content in their local soil environment by releasing a diverse, highly polymeric blend of substances (e.g. extracellular polymeric substances [EPS] and mucilage). Although this concept is well accepted, the physical mechanisms by which EPS and mucilage interact with the soil matrix and determine the soil water dynamics remain unclear. High-resolution X-ray computed tomography revealed that upon drying in porous media, mucilage (from maize [Zea mays L.] roots) and EPS (from intact biocrusts) form filaments and two-dimensional interconnected structures spanning across multiple pores. Unlike water, these mucilage and EPS structures connecting soil particles did not break up upon drying, which is explained by the high viscosity and low surface tension of EPS and mucilage. Measurements of water retention and evaporation with soils mixed with seed mucilage show how these one- and two-dimensional pore-scale structures affect macroscopic hydraulic properties (i.e., they enhance water retention, preserve the continuity of the liquid phase in drying soils, and decrease vapor diffusivity and local drying rates). In conclusion, we propose that the release of viscous polymeric substances and the consequent creation of a network bridging the soil pore space represent a universal strategy of plants and bacteria to engineer their own soil microhydrological niches where stable conditions for life are preserved.
On the importance of rhizosphere conductance and soil-root contact in drying soils
Koch, Axelle; Cai, Gaochao; Ahmed, Mutez Ali; et al. (2025)
Annals of Botany
Background and Aims Root water uptake (RWU) is influenced by rhizosphere conductance and soil–root contact, which vary with soil texture and root structure, including root hairs. Current simplified models often fail to capture the spatial complexity of these interactions in drying soils. The aim of this study was to examine how rhizosphere conductance, soil–root contact and root hairs affect RWU. Methods We used an explicit three-dimensional functional–structural model to investigate how root and rhizosphere hydraulics influence the transpiration rate–leaf water potential relationship of two maize (Zea mays) genotypes (with and without root hairs) grown in two contrasting soil textures (loam and sand) during soil drying. The model incorporated rhizosphere resistance in series with radial root resistance, with the latter being influenced by maturation (development of apoplastic barriers with age). It considered two critical processes: (1) the decrease in soil water potential between bulk soil and the soil–root interface; and (2) the extent of soil–root contact. Key Results The simulations revealed that RWU was highly soil texture specific. In loam, the non-linearity in the transpiration rate–leaf water potential relationship was attributable primarily to localized uptake fluxes and high rhizosphere resistance as soil dried. In sand, however, where soil–root contact was less effective, rhizosphere conductance became a significant limiting factor for RWU, even at relatively higher soil water potential in comparison to loam. Root hairs did not make a significant contribution to rhizosphere conductance, probably owing to the dominant effect of soil–root interaction. Additionally, variations in root hydraulic conductance and its change with root tissue age impacted the accuracy of the model. Conclusions The explicit three-dimensional model provides a more precise representation of RWU dynamics by pinpointing exact uptake locations and primary limiting factors and by quantifying the proportion of root surface actively engaged in RWU. This approach offers notable improvements over conventional models for understanding the spatial dynamics of water uptake in different soil environments.
Soil Hydraulic Constraints on Stomatal Regulation of Plant Gas Exchange
Wankmüller, Fabian; Carminati, Andrea (2024)
Progress in Botany ~ Progress in Botany
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 hydraulics) and the gas exchange between vegetation and atmosphere (via stomatal regulation). In this article, we review the principles of water flow in soil and plants and the links to stomatal responses to decreasing soil water availability. We make use of a soil-plant hydraulic framework to define the physical constraints on transpiration and predict stomatal responses. We then discuss the role of soil-plant hydraulics for different plant water use strategies (i.e. degree of iso/anisohydry) with changing soil hydraulic properties, root hydraulic distribution and xylem vulnerability.
Unsaturated water flow across soil aggregate contacts
Carminati, Andrea; Kaestner, A.; Lehmann, Peter; et al. (2008)
Advances in Water Resources
Investigation of water imbibition in porous stone by thermal neutron radiography
Hassanein, R.; Meyer, H.O.; Carminati, Andrea; et al. (2006)
Journal of Physics D: Applied Physics
Analyzing the fabric of soil aggregates
Kaestner, A.; Lehmann, Peter; Carminati, Andrea; et al. (2005)
Stomatal regulation prevents plants from critical water potentials during drought: Result of a model linking soil–plant hydraulics to abscisic acid dynamics
Wankmüller, Fabian; Carminati, Andrea (2022)
Ecohydrology
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 introduce a model of stomatal regulation that results in similar stomatal behaviour without presupposing an optimality principle. By contrast, the proposed model explains stomatal closure based on a well-known component of stomatal regulation: abscisic acid (ABA). The ABA level depends on its production rate, which is assumed to increase with declining leaf water potential, and on its degradation rate, which is assumed to increase with assimilation rate. Our model predicts that stomata open until the ratio of leaf water potential to assimilation rate, proportional to ABA level, is at a minimum. As a prerequisite, the model simulates soil-plant hydraulics and leaf photosynthesis under varying environmental conditions. The model predicts that in wet soils and at low vapour pressure deficit (VPD), when there is no water limitation, stomatal closure is controlled by the relationship between photosynthesis and stomatal conductance. In dry soils or at high VPD, when the soil hydraulic conductivity limits the water supply, stomatal closure is triggered by the sharp decline in leaf water potential as transpiration rate increases. Being adaptive to changing soil and atmospheric conditions, the proposed model can explain how plants are enabled to avoid critical water potentials during drought for varying soil properties and atmospheric conditions.
Consistent prokaryotic community patterns along the radial root axis of two Zea mays L. landraces across two distinct field locations
Tyborski, Nicolas; Koehler, Tina; Steiner, Franziska A.; et al. (2024)
Frontiers in Microbiology
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 compared to selection imposed by the agricultural environment. Landraces may have traits shaping their microbiome, which were lost during the breeding of modern varieties, but knowledge about this is scarce. We investigated prokaryotic community composition along the radial root axis of two European maize (Zea mays L.) landraces. A sampling gradient included bulk soil, a distal and proximal rhizosphere fraction, and the root compartment. Our study was replicated at two field locations with differing edaphic and climatic conditions. Further, we tested for differences between two plant developmental stages and two precipitation treatments. Community data were generated by metabarcoding of the V4 SSU rRNA region. While communities were generally distinct between field sites, the effects of landrace variety, developmental stage, and precipitation treatment were comparatively weak and not statistically significant. Under all conditions, patterns in community composition corresponded strongly to the distance to the root. Changes in α- and β-diversity, as well as abundance shifts of many taxa along this gradient, were similar for both landraces and field locations. Most affected taxa belonged to a core microbiome present in all investigated samples. Remarkably, we observed consistent enrichment of Actinobacteriota (particularly Streptomyces, Lechevalieria) and Pseudomonadota (particularly Sphingobium) toward the root. Further, we report a depletion of ammonia-oxidizers along this axis at both field sites. We identified clear enrichment and depletion patterns in microbiome composition along the radial root axis of Z. mays. Many of these were consistent across two distinct field locations, plant developmental stages, precipitation treatments, and for both landraces. This suggests a considerable influence of plant-mediated effects on the microbiome. We propose that the affected taxa have key roles in the rhizosphere and root microbiome of Z. mays. Understanding the functions of these taxa appears highly relevant for the development of methods aiming to promote microbiome services for crops.
Microplastics in agricultural soils: The role of soil texture in modulating oxygen diffusivity and soil respiration
Nuñez, Jonathan; Jimenez-Martinez, Joaquin; Carminati, Andrea; et al. (2025)
Soil Biology and Biochemistry
The presence of microplastics (MPs) in soils impacts nutrient cycling and soil respiration. However, the mechanisms underpinning the direction and magnitude of these effects on soil are uncertain. We hypothesized that the presence of MPs affects pore connectivity, leading to changes in oxygen (O2) diffusivity and soil respiration. Furthermore, we anticipated that the magnitude of the effects would be dependent on both soil texture and MPs morphology. 1 % (w/w) PET MPs fibers (500 μm length) and fragments (125–250 μm) were spiked into rhizotrons filled with either clay or sandy loam soils. O2 diffusivity differences were determined in microcosm using an oxygen-free chamber. The O2 concentration in the soil was also measured in optimal conditions for respiration. O2 diffusivity and concentration were measured using optode imaging. Respiration was estimated from cumulative CO2 and changes in the size of the water-extractable carbon pool. Adding MPs decreased O2 concentration in the sandy loam soil (167.4 ± 6.1 mg L−1 air), with a greater reduction observed for fragments (15 %) compared to fibers (12 %). Soil respiration decreased by 40 % in both fragment and fiber treatments in alignment with the reduction in oxygen concentration. Conversely, in the clay soil, the addition of fibers and fragments resulted in a 13 and 7 % increase in O2 concentration compared to the control (177.9 ± 3.8 mg L−1 air). Both changes in oxygen concentration and diffusivity, show a similar response to MPs for the two soils. These findings indicate that the effects of MPs on soil respiration are likely driven by changes in O2 dynamics. However, the MPs' impact on O2 dynamics depends on soil particle size distribution. Future research should consider MP size, morphology, and soil particle distribution interactions to assess MPs' impacts on soil functions.

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Andrea Carminati

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