The spatial distribution of root water uptake at the ecosystem scale is difficult to assess, and therefore our knowledge of how ecosystem-related and abiotic factors affect root water uptake and its patterns is still limited. This presentation summarizes the results of observations of root water uptake in two contrasting vegetation types: grassland and forest along community diversity gradients.
Based on field studies in both a grassland and a forest system, we investigated how root water uptake changes with ecosystem assembly. We used a water balance method to estimate (a) vertical profiles of root water uptake in grassland systems and (b) horizontal distribution of water uptake in forests, in both cases along species diversity gradients. In both cases, we find that species diversity strongly affects the location and increases the magnitude of root water uptake. In grasslands, the relationship can be directly linked to deeper uptake by species with deep root systems and higher water requirements, suggesting complementarity in resource use. In forests, uptake is enhanced in the main root zone where both the number of tree species and basal area are high, although the underlying mechanisms remain elusive.
Overall, our observations show an enhanced capacity for water uptake in diverse ecosystems.
In the future, further insights will be gained by combining techniques for assessing root water uptake at the individual and ecosystem scale together with plant and soil hydraulic assessments.
How to cite: Hildebrandt, A., Demir, G., Guderle, M., Westermann, S., Fischer-Bedtke, C., Metzger, J. C., Guswa, A., Magh, R.-K., and Roscher, C.: Effect of ecosystem structure on spatial distribution of root water uptake in a grassland and forest ecosystem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9772, https://doi.org/10.5194/egusphere-egu25-9772, 2025.
Root-zone water-storage capacity (Sr) represents the maximum value of soil-water stored in the active soil profile, and available for vegetation growth. The mapping of Sr over relatively large spatial scales necessitates the assumption of simplified functions and characteristics of an agroecosystem. Currently, Sr is still determined by resorting only to soil attributes, such as the plant-available water (PAW) that is based on the concepts of field capacity and permanent wilting, as well as on a static determination of the depth of the uniform soil profile.
In this study, we propose a novel approach to identify Sr as an indicator of soil-vegetation functioning (hereinafter referred to as Sr,i), depending not only on soil properties but also on vegetation characteristics and climatic regimes. The integrated approach proposed in this study accounts for the following two factors: (i) the entire shape of the soil-water retention function, which is much more informative of the amount of energy required to remove soil-water for vegetation needs, as well as (ii) the maximum value of an effective rooting depth depending on both local weather condition and land use.
Our contribution to this session consists of two parts:
- A preliminary part takes advantage of a detailed field drainage experiment and aims at demonstrating the superior performance of the Sr,i indicator compared with PAW;
- The subsequent part discusses the result of mapping Sr,i on a regional scale.
We show that Sr,i, together with other single or compound indicators, can effectively contribute to gaining a better understanding of agroecosystem’s vulnerability to drought. Moreover, employing a probabilistic framework, Sr,i helps identify the most likely Priority Intervention Areas (PIAs) that require the implementation of tailored management strategies to enhance their potential resilience.
This study was partly carried out within the “Agritech National Research Center” and received funding from the European Union Next-Generation EU [Piano Nazionale di Ripresa e Resilienza (PNRR) – Missione 4 Componente 2, Investimento 1.4 – D.D. 1032 17/06/2022, CN00000022]. The outcomes of this research are within the action Spoke #3, Task 3.2.1, “Solutions for soil quality assessment and protection”. This presentation reflects only the authors’ views and opinions, neither the European Union nor the European Commission can be considered responsible for them.
How to cite: Romano, N., Mazzitelli, C., and Nasta, P.: Is there anything new about determining the root-zone water-storage capacity over large areas?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4821, https://doi.org/10.5194/egusphere-egu25-4821, 2025.
Vegetation responses to soil moisture limitation play a key role in land-atmosphere interactions and are a major source of uncertainty in future projections of the global water and carbon cycles. Plant water-use strategies---i.e., regulation of transpiration rates as the soil dries---are highly dynamic across space and time, presenting a major challenge to developing scalable inferences about ecosystem responses to water limitation. Here we show that, when aggregated globally, water-use strategies derived from point-based soil moisture observations exhibit emergent patterns across and within climates and vegetation types along a spectrum of aggressive to conservative responses to water limitation. Water use becomes more conservative, declining more rapidly as the soil dries, as mean annual precipitation increases and as woody cover increases from grasslands to savannas to forests. We embed this empirical synthesis within an ecohydrological framework to show that key ecological (leaf area) and hydroclimatic (aridity) factors driving competition for water explain up to 77% of the variance in water-use strategies within ecosystem types. All biomes respond to ecological and hydroclimatic competition by shifting toward more aggressive water-use strategies. However, woodlands reach a threshold beyond which water use becomes increasingly conservative, reflecting the greater hydraulic risk and cost of tissue damage involved in sustaining high transpiration rates under water limitation for trees than grasses. These findings highlight the importance of characterizing the dynamical nature of vegetation water-use strategies to improve predictions of ecosystem responses to climate change.
How to cite: Morgan, B., Araki, R., Trugman, A., and Caylor, K.: Ecological and hydroclimatic determinants of vegetation water-use strategies, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14060, https://doi.org/10.5194/egusphere-egu25-14060, 2025.
Roots are fundamental plant organs mediating water and nutrient uptake, among other functions. The amount of soil water available to roots fluctuates over time. With increasing climatic variability and extended periods of drought, it is important to understand how roots respond to fluctuations in available soil water. Furthermore, soil-vegetation-atmosphere transfer models need a precise characterization of the spatial and temporal organization of root systems for more accurate predictions of water fluxes mediated by vegetation.
It has been shown that root systems dynamically adapt to seasonal changes in soil moisture by shifting their growth allocation from the upper soil to deeper depths as a dry period progresses. In previous work we explored the phenomenon of “Hydromatching” in young individual maize plants, which involves the daily-timescale promotion of root growth in a newly wetted soil layer accompanied by a decline in root growth in drier layers. Here we report results from a 1.5-year-long field study in Luxembourg, where we investigated if the results of Hydromatching can also be observed at a community scale in a temperate grassland.
Near a well-instrumented weather station, we installed 12 minirhizotrons enabling us to obtain images of roots growing down to a soil depth of 115 cm. We imaged the tubes every two weeks, with increased sampling frequency shortly after major precipitation events during the growing season. We calculated local root growth rates at different depths and related them to local soil moisture and temperature variations measured by four sensors located at depths of 10, 20, 40 and 60 cm.
We found that, even under strong variations in temperature, soil moisture remained a more important predictor of root growth at 10, 20 and 40 cm depth, despite the site being more energy than water-limited. Following rain events, root growth distribution shifted from the deeper soil to the shallow soil within 1-5 days, demonstrating the potential effect of Hydromatching at community scale. Following a renewed dryness, root allocation shifted again to the deeper soil within 7-8 days from the rain event, showing a remarkably dynamic nature of the root systems in the grassland. The 2023 spring-summer transition saw a much larger change in soil moisture compared to the 2022 transition. Nonetheless, during the seasonal change both years exhibited a significant and similar growth promotion in the deeper soil coupled with a decline in root length at shallower depths. These results suggest that daily root distribution shifts following rewetting events are likely regulated by environmental variables while seasonal shifts seem to be dictated by phenological factors. Regardless, both daily and seasonal shifts appear to reflect an optimization strategy, consisting of the promotion of root growth in moist areas while discarding roots where moisture is less accessible. Such strategy might have evolved to cope with soil water heterogeneity while efficiently managing carbon budgeting.
How to cite: Ceolin, S., Schymanski, S., and Klaus, J.: Root distribution shifts at both seasonal and daily scales following precipitation events in a temperate grassland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17498, https://doi.org/10.5194/egusphere-egu25-17498, 2025.
Soil water availability is a critical factor in determining how plants regulate their water relations, with drying soils imposing hydraulic constraints that affect root water uptake and stomatal behavior. As soils dry, their hydraulic conductivity is reduced, limiting water movement to the roots and ultimately impacting the flow of water within the soil-plant continuum. When root water uptake exceeds the flow rate allowed by the bulk soil, transpiration cannot be sustained for long. In theory, the critical point when root water uptake is no longer matched by soil water flow should be concomitant with a local depletion of water in the rhizosphere. However, such local depletion has never been observed.
In this study, we used a time-series neutron radiography performed at the ICON beamline of the Paul Scherrer Institute (Villigen PSI, Switzerland) to visualize and quantify root water uptake and soil water distribution in maize samples. Seedlings were grown under controlled conditions in rhizoboxes filled with sandy and loamy soils for two weeks, followed by a period of progressive drying. High-resolution imaging revealed a clear shift in water uptake patterns as the soil dried: initially, water was extracted predominantly from the bulk soil, but under drier conditions, uptake increasingly shifted to the rhizosphere. As soil drying progressed, the rate of water uptake from the rhizosphere became insufficient to meet the transpiration demand. The critical point when water uptake shifted from the bulk to the rhizosphere soil occurred at less negative water potentials in sandy soils (-4 to -5 kPa) than in loamy soils (-100 to -300 kPa), reflecting the differences in hydraulic properties between the two soil types.
These results show that under drought conditions, the rhizosphere serves as a primary water source for plants but cannot fully sustain transpiration over time, ultimately leading to stomatal closure and reduced water loss. By providing direct experimental evidence of how soil hydraulic limitations and rhizosphere water dynamics shape plant responses, this study provides new experimental evidence on the key role of rhizosphere water dynamics in regulating plant water use.
How to cite: Di Bert, S., Benard, P., Jia, R., Wankmüller, F. J. P., Azad, S., Kaestner, A., Nardini, A., and Carminati, A.: Declining Soil Hydraulic Conductivity Shifts Root Water Uptake from Bulk Soil to the Rhizosphere and Triggers Stomatal Closure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12200, https://doi.org/10.5194/egusphere-egu25-12200, 2025.
The symbiosis with arbuscular mycorrhizal fungi (AMF) can enhance the drought resilience of associated crops, for example, by modifying the belowground morphology of host plants. Additionally, the fungal symbionts are key drivers of organic matter (OM) allocation at the root-soil interface: AMF can modify the quantity and composition of plant-derived carbon (C) inputs to the soil and change their fate through altered microbial processing, enhanced organo-mineral interactions, or changes in spatial soil arrangements. However, the effects of future drought events on the intricate linkages between fungal symbionts, host plants, and their feedback on plant-derived OM dynamics under water scarcity remain poorly understood. This study aims to understand (1) how AMF, in conjunction with the host plant´s morphological response, influence plant-derived C inputs and their allocation across OM pools, and (2) whether AMF-mediated changes in the fate of plant-derived C differ between well-watered and drought conditions.
Two maize genotypes, an AMF-resistant mutant and an AMF-receptive wildtype, were grown in a pot experiment under well-watered and drought conditions. 13CO2 pulse labeling was employed to trace the allocation of assimilated C throughout the plant-soil system and across functional soil OM pools, which were isolated via density fractionation.
Drought strongly reduced 13C fixation of maize plants, limiting overall plant-derived C inputs to the soil and causing its accumulation in readily water-extractable forms. The fate of plant-derived C under both well-watered and drought conditions was modified by the symbiosis of the host plant with AMF: The greater compensatory root length growth of AMF-deficient plants promoted the occlusion of particulate OM in aggregates under well-watered conditions, whereas this effect did not prevail under drought. In contrast, the greater net-rhizodeposition of AMF-receptive plants facilitated the incorporation of plant-derived C into mineral-associated OM under both watering regimes, partially mitigating the drought-induced accumulation of plant-derived C in water-extractable form.
Our findings underscore the significant impact future drought spells will impose on plant-derived OM inputs and composition at the root-soil interface in cropping systems. Notably, the symbiosis of crop plants with AMF has the potential to enhance the persistence of root-derived OM in agricultural soils, not only under sufficient water supply but also during periods of drought.
How to cite: Steiner, F., Tyborski, N., Veciana, J., Abdalla, M., Lüders, T., Pausch, J., Mueller, C. W., and Vidal, A.: Symbioses with arbuscular mycorrhizal fungi alter allocation of plant-derived carbon to soil organic matter pools under drought and well-watered conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19311, https://doi.org/10.5194/egusphere-egu25-19311, 2025.
Crop performance under limited soil water availability depends on a successful coordination of physiological processes at root, stem, and leaf level. This includes efficient stomatal regulation, root modifications and prevention of xylem embolism. In woody crops, drought-induced mortality is predominantly linked to xylem hydraulic failure by gas embolism blocking water transport from roots to leaves – but does this matter in a managed agricultural system? In this presentation, I will show experimental data collected under greenhouse and field conditions on the sequence of physiological and anatomical events in response to progressive drought stress. This includes a demonstration of applications of X-ray computed tomography to study leaf, stem and root responses to water stress in hazelnut and poplar. I will discuss the relevance of data in the context of precision irrigation management.
How to cite: Knipfer, T.: Dry roots? What crop water relations tell us about irrigation management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-244, https://doi.org/10.5194/egusphere-egu25-244, 2025.
Grapevines from the hyper-arid Atacama Desert possess unique hydraulic and biomechanical root adaptations that confer resilience to extreme drought and salinity. Here, we provide insights into root hydraulic properties, tissue–water relations, and mechanical traits to investigate resilience strategies in naturalized genotypes (R-65 and R-70) and commercial rootstocks (101-14Mgt and 110-R). Using root pressure probes, uniaxial tensile tests, pressure-volume analyses, and fluorescence microscopy, we evaluated the effects of salinity (0–250 mM NaCl) and severe drought on fine root functionality. The results reveal that the hyper-arid genotypes integrate superior hydraulic conductivity, elastic-plastic mechanical behavior, and reduced cortical damage to withstand high salinity and water stress. Although R-65 and R-70 maintained larger root diameters, higher water content, and stable osmolality under extreme salinity and drought conditions, commercial rootstocks showed increased stiffness, significant cortical lacunae formation, and reduced recovery capacity. These responses align with xerophytic adaptations that safeguard fine root functionality through enhanced energy dissipation, structural flexibility, and water retention, thereby minimizing permanent damage. Complementary hydraulic and biomechanical traits are critical for maintaining fine root integrity and stress resilience in hyperarid environments. This integrated analysis of hydraulic and mechanical traits highlights the potential of Atacama-adapted genotypes as genetic resources for breeding resilient crops. These findings contribute to the development of sustainable agricultural practices in saline- and drought-prone regions.
How to cite: Cuneo, I., Knipfer, T., and Barrientos-Sanhueza, C.: Integrated Hydraulic and Biomechanical Strategies of Grapevine Fine Roots for Adaptation to Aridity and Salinity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-316, https://doi.org/10.5194/egusphere-egu25-316, 2025.
Earlier studies have shown that plants may use their root systems to communicate with other plants, this enables them to recognize and react to genetic relatedness and differentiate between self and non-self roots. Our ground-breaking study has shown that crops in the Solanaceae family, particularly bell pepper and tomatoes (cherry tomato and field tomato), can communicate through the root systems based on their degrees of relatedness (DOR). The study examined the effects of root-root communication on physiological and metabolic aspects in tomatoes and bell pepper plants, and the results showed that as DOR decreased, root growth and respiration increased in L-DOR plants with lower organic carbon and protein levels, suggesting that genetic relatedness plays a key role in root communication within the Solanaceae. Building on these findings, our objective was to know how plants respond differently to plants that are not genetically related or are outside their family. We examined the physiological and morphological changes in response to neighbor relatedness within the Solanaceae family (cherry tomato (C) and bell pepper (B)) and between the Solanaceae and Fabaceae family (pea (P)). Nine combinations were studied, examining self (C, B, P) and non-self-interactions (CC, CB, CP, BB, BP, PP). Two separate experiments were conducted; using rhizoslides, a paper-based growth system, and a pot experiment with a four-pot design with a split root system. The results demonstrated that cherry tomato increased plant height, stem diameter, chlorophyll content, photosynthesis, stomatal conductance, and root respiration parameters when paired with bell pepper. In contrast, when paired with cherry tomato, bell pepper exhibited decreases in all these parameters, indicating that bell peppers are beneficial neighbors to cherry tomato, whereas cherry tomato are costly neighbors to bell pepper. However, both cherry tomato and bell pepper performed better when grown with a neighbor from outside the family, pea. Pea showed an increase in all parameters when grown alone or with a Solanaceae neighbor but decreased when grown with a closely related neighbor. By understanding natural plant communication networks from both inside and outside of the Solanaceae family, root-to-root communication may result in improved agricultural techniques that increase crop resilience and yield.
How to cite: Miti, M., Ko, A. N., Falik, O., and Rachmilevitch, S.: Family Ties: Root-Root Communications Within and Outside the Family (Solanaceae to Fabaceae), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1117, https://doi.org/10.5194/egusphere-egu25-1117, 2025.
Roots, as the hidden half of plants, are the main organ absorbing water and nutrients from the soil. Yet, research into plant roots has lagged behind investigations of aboveground plant organs due to the difficulty of continuous monitoring of phenotypic changes in root architecture underground in a non-destructive manner. In this study, we developed a novel minirhizotron system based on common components of the fluorescence microscope. We examined the possibility of a pilot system for imaging green fluorescent protein (GFP) expression in roots within rhizoslides and glass containers and tested different parameters in order to achieve the best fit for imaging. Our results demonstrate that imaging GFP expression in roots provides a clearer visualization of the root system, effectively increasing an observable number of roots by minimizing interference from the soil compared to RGB images. We further miniaturized the imaging system and integrated it into the minirhizotron. The developed fluorescence minirhizotron is fully automated, high-throughput, and non-invasive allowing us to detect clear, continuous, in situ GFP fluorescence in roots. It is applicable across a wide range of scenarios. Currently, our ongoing work focuses on producing stress-inducible GFP expression in transgenic tobacco lines to enable rapid and early detection of plants under stress in a non-destructive manner. This study could help in distinguishing the roots of different plants and provide a potential contribution to breeding plants or in developing agro-techniques to save water, increase nutrient uptake, and improve crop yields in the era of climate change.
How to cite: Xu, X., Ben-Tovim, O., Barak, S., Ephrath, J. E., and Lazarovitch, N.: An automated minirhizotron system for in situ imaging of GFP expression in roots, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3352, https://doi.org/10.5194/egusphere-egu25-3352, 2025.
Individual plants vary in their ability to respond to environmental changes. For dynamic responses in plants, long-distance carbon (C) transport is required to support growth. Therefore, investigating C allocation in plants is crucial for developing a mechanistic understanding of plant functioning. However, little is known about short-term assimilate transport patterns and velocities, as literature values from singular and invasive measurements are hard to interpret for a highly susceptible system. To study the transport of photo assimilates within plants, we developed phenoPET, a plant dedicated positron emission tomography (PET) scanner. While PET scanners have been widely used in medical science since decades, their use in plant research is less common. For tracing the transport, carbon dioxide containing the short-lived positron-emitting isotope carbon-11 (11C) is applied as 11CO2 to a single leaf or the whole canopy of a living plant. The plant fixes CO2 and the 11C is subsequently transported in the form of photosynthates towards C sinks, e.g. through leaf and stem towards the root system. The decaying tracer can then be located inside the plant by detecting its radiation. To this end, the living plant is placed in the field-of-view of the scanner, which is a volume with a diameter of 18 cm and a height of 20 cm. A lifting table can move the scanner vertically and allows for repeated measurements of different regions of interest along the plant axis. The phenoPET system is located in a climate chamber equipped with LED panels in order to create defined environmental conditions.
In our presentation, we will highlight our workflow for gathering quantitative data on C tracer transport velocities between different plant types, single plants, for different plant parts, during a day, and over days. We believe that this will provide new insights into the functioning and dynamics of C transport processes in in the plant-soil system.
How to cite: Streun, M., Scherer, B., Metzner, R., Huber, G., Pflugfelder, D., Chlubek, A., Koller, R., Knief, C., Wüstner, P., Zimmermann, E., and Natour, G.: phenoPET: Observing Carbon Transport within Individual Plants, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4311, https://doi.org/10.5194/egusphere-egu25-4311, 2025.
The arid Northwest of China is the main production area of China's jujube, where reasonable irrigation and fertilization strategies is key to improving the quality and production of jujube trees. While current research primarily focuses on the effects of different irrigation regimes on jujube growth, there is a lack of systematic studies on the relationship between potassium application amount and jujube growth and metabolism, making it challenging to provide clear guidance for jujube fertilization strategies. This study investigated the effects of different potassium application amount (240, 180, 120, and 0 kg·hm⁻²) on the growth and production efficiency of jujube trees. The results showed that the application of potassium fertilizer improved water use efficiency of jujube trees, significantly promoted their growth, and increased transpiration rate and production efficiency with higher potassium application amount. The water-potassium transport model in the root zone and the production model of jujube trees under drip irrigation with potassium application were calibrated and validated using experimental data from four potassium application treatments. Nine orthogonal numerical experiments were designed with the irrigation volume and potassium application amount as variables. The results revealed that the irrigation volume and potassium application amount significantly influenced the growth of jujube trees (P < 0.05), with a notable interaction effect between the two. When the potassium application rate was 240 kg·hm⁻² and the irrigation volume was 180 mm, the water use efficiency of the jujube trees was optimized, aligning better with the water-saving and high-production goals of the Xinjiang region. The maximum root-uptake radius of jujube trees for soil water and potassium was 50–70 cm. Within this radius, the potassium concentration significantly decreases with increasing distance from the root system, while beyond the absorption radius, potassium infiltrates vertically into deeper soil layers along with irrigation water. An empirical formula relating the transpiration rate and production of jujube trees to irrigation volume and potassium application amount under drip irrigation conditions were established in this study, offering guidance for irrigation and potassium application strategies in arid regions.
How to cite: Yao, C., Wu, J., Guo, C., and Qin, S.: Optimization of Irrigation and Potassium Application for Improved Jujube Production in arid Northwest China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10903, https://doi.org/10.5194/egusphere-egu25-10903, 2025.
It is not known whether modern crop breeding lost valuable root-soil interface traits present in landraces beneficial to soil-carbon storage, nutrient and water use efficiency, and remediation of degraded soil structure. Landraces are defined as crop genotypes which are locally adapted to environmental and management conditions. These ancient cultivars may provide a valuable source of genetic diversity and agronomic traits which can be bred into higher-yielding modern cultivars to improve yield stability under lower input or stressed conditions. Within the Highlands of Scotland, the “Bere” barley landrace is a multipurpose crop with cultural importance, early maturity, and evidence of advantageous root-soil adaptations to micronutrient deficiency.
In this study, three Bere genotypes and the modern barley cultivar KWS Curtis were grown under highly controlled conditions to evaluate genotype differences at the root-soil interface. In a seedling assay, plants were grown in growth cabinets for 4 days in sandy loam soil packed to a defined bulk density and water contents. This rapid and low-cost methodology demonstrated a high level of reproducibility in rhizosheath size and root traits, with no significant difference between root hair length and root system length between experiments. Additionally, two of the three Bere landraces were found to have a significantly larger rhizosheath (P=0.001) than the modern cultivar KWS Curtis at the earliest stage of seedling growth (GS 10, first leaf emergence): 39% and 19% increase for “Unst” and “Challoner” vs KWS Curtis, respectively. Conversely, KWS Curtis had much greater (P<0.001) above ground biomass than the three Bere genotypes with “Unst” having a 93% lower above ground biomass than KWS Curtis. This suggests that the modern cultivar favoured above-ground allocation of resources over root exudation in early seedling growth.
This study serves as a platform to investigate fine-scale rhizosphere characteristics and spatial distribution of soil modification through root hair-exudate-microbial interactions. The screening approach provides a rapid assay to select genotypes with favourable traits from seedling characteristics, which will be verified with more mature plants in future research.
How to cite: Graham, S., George, T., Marin, M., Malik, A., and Hallett, P.: Curtis and The Three Beres: investigating early seedling root-soil interface traits in modern and landrace barley genotypes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4453, https://doi.org/10.5194/egusphere-egu25-4453, 2025.
Plants are increasingly exposed to water stress under climate change, posing significant challenges for accurate simulation of carbon and water fluxes in terrestrial ecosystems. Most land surface models simulate the regulation of water and carbon fluxes in response to soil moisture stress through empirical soil hydraulic schemes. However, these schemes often introduce significant uncertainties in water and carbon simulations. To address this, the Community Land Model version 5 (CLM5) introduced a plant hydraulic stress routine that explicitly models water transport through vegetation via a hydraulic framework, improving the representation of vegetation water potential, root water uptake, and plant water stress1. However, including plant hydraulics introduces additional parameters that are difficult to constrain due to limited field data and high variability. Understanding the influence of these plant hydraulic parameters on water and carbon flux modeling is crucial for model improvement and prediction accuracy.
In this study, we used a parameter perturbation approach to investigate the role of plant hydraulic parameters at 14 experimental sites in Europe, representing diverse plant functional types (PFTs) and climate zones. Using CLM5, we performed 128 ensemble simulations per site, systematically varying three key hydraulic parameters: plant- and root-segment maximum conductance (kmax and krmax) and water potential at 50% loss of segment conductance (psi50). The perturbation ranges were informed by previous parameter perturbation experiments2,3. We evaluated: (i) how the model represented plant hydraulic dynamics (i.e., vegetation water status and plant-segment conductances), (ii) the sensitivity of carbon and water fluxes—gross primary production (GPP) and evapotranspiration (ET)—to parameter variation, and (iii) model performance compared to in-situ observations.
The results showed that the model successfully captured seasonal variations in plant-segment conductance and vegetation water potential, which were reflected in the seasonal dynamics of GPP and ET. However, at drought-prone sites, the model overestimated ET reductions during summer compared to observations, due to a steep decline in root-segment conductance and stomatal closure. This highlights the need for improved parameterization of psi50 and krmax to better represent plant responses to extreme drought. In addition, ensemble simulations revealed substantial sensitivity of GPP and ET to parameter perturbations, with variations up to 50% in GPP and 30% in ET depending on PFT and climate zone. These results underscore the importance of considering the variability in plant hydraulic properties, particularly kmax and krmax, which span several orders of magnitude.
To address these uncertainties, the next steps of this work will focus on refining the parameterization by integrating data on plant hydraulic traits from existing databases4,5. This approach will help constrain parameter ranges across ecosystems and climate zones, particularly for drought-prone sites. Improving the representation of plant hydraulic traits will enhance predictions of ecosystem responses to water stress and the reliability of land surface models under current and future climate scenarios.
References
- 1Kennedy et al. (2019). 10.1029/2018MS001500
- 2Kennedy et al. (2024). 10.22541/essoar.172745082.24089296/v1
- 3Eloundou et al. (2024). 10.5194/egusphere-egu24-16086
- 4Kattge et al. (2020). 10.22541/10.1111/gcb.14904
- 5Baca Cabrera et al. (2024). 10.1002/pld3.582
How to cite: Baca Cabrera, J. C., Eloundou, F., Hendricks Franssen, H.-J., Schnepf, A., Vanderborght, J., and Lobet, G.: The significance of plant hydraulic parameters for modeling carbon and water fluxes across European climate zones and PFTs with CLM5, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6021, https://doi.org/10.5194/egusphere-egu25-6021, 2025.
Plants are the main connection between soil and atmosphere. Below ground, nitrogen, carbon, and water fluxes are mediated by roots, which therefore strongly influence nitrogen, carbon, and water distributions throughout the soil profile and impact, for instance, if conditions favorable for denitrification occur or not. However, the representation of roots in biogeochemical models is often strongly simplified, allowing only for a static prescribed root development. Further, the root system is normally not taken into account during model calibration, due to a lack of measurements. This disregard of roots prevents model veracity. In this study, we evaluate three model settings of the biogeochemical model framework LandscapeDNDC and compare them to site measurements of winter wheat and maize on a stony and a silty soil to illuminate and quantify these shortcomings. As a baseline, the model is calibrated regarding above ground parameters and measurements only. These results are compared to calibrations on above and below ground parameters and measurements with two different root models. One static root model and one dynamic root model proposed by Jones et al. in 1991. The calibrated settings yield overall comparable qualities of fit for the above ground properties. As expected, the root depth and the root length density are better represent after calibration. The best qualities of fit in the validation are relative root mean square errors (coefficients of determination) of 0.76 (0.36) and 0.39 (0.86) for the root length density and root depth, respectively. At last, for the best-fit model run of each setting, the nitrogen balance is analysed. On the stony soil, the simulated nitrate leaching from the baseline is 80 % smaller than in a setting where the roots were properly calibrated. In line, the plant nitrogen uptake was on average 40 kgNha-1 bigger in the baseline compared to the other settings. These large impacts on the nitrogen cycle illustrate the need for joined measurements of roots and nitrogen fluxes.
How to cite: Boos, C., Nguyen, T. H., Cai, G., Morandage, S., Kraus, D., Haas, E., and Kiese, R.: Root simulations in a biogeochemical model and impacts on nitrogen fluxes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9480, https://doi.org/10.5194/egusphere-egu25-9480, 2025.
The growing demand for sustainable food production requires innovative farming techniques that optimise water use and minimise environmental impacts. This experiment tested the cultivation of lettuce (Lactuca sativa L.) in a greenhouse environment. Two cropping systems were tested, a soil-based system with a humus-sand soil and a perlite system. Two different levels of water management were applied for the soil-based system, these were 70% and 90% of the minimum water capacity (WCmin). Both the soil and perlite systems were irrigated daily to ensure adequate water supply. The nutrient supply methods included nutrient solution and compost treatments in addition to the control group.
Key growth parameters including plant height, leaf number, head diameter, Fv/Fm fluorescence ratio and SPAD values were monitored weekly for five weeks. In addition, biomass (shoot and root mass), root length, and chlorophyll and carotenoid content were determined at the end of the experiment to evaluate the overall productivity and physiological status of the plants.
The results showed that in perlite-based systems, plant growth was faster, while soil-based cultivation showed more stable growth, especially the 70% WCmin treatment resulted in a more balanced growth compared to the 90% WCmin treatment. Based on nutrient replenishment, it can be said that nutrient-based treatments significantly increased plant biomass, especially wet head weight and chlorophyll content. Statistical analyses confirmed the differences between treatments, highlighting the effects of both nutrient supply and water management strategies on plant growth.
The results underline the importance of optimising water use in closed environment cropping systems. By contributing to the development of sustainable water management strategies for lettuce production, this study is in line with the main objectives of the EU Green Deal and the UN Sustainable Development Goals. These results provide practical insights into efficient water use, nutrient use and plant physiological responses under different growing conditions, pointing the way towards more sustainable, resilient food production systems.
The research presented in the article was carried out within the framework of the Széchenyi Plan Plus program with the support of the RRF 2.3.1 21 2022 00008 project.
How to cite: Kiss, N. É., Pásztorné Orosz, A., Szabó, A., Kun, S., Tamás, J., and Nagy, A.: Water management strategies for lettuce cultivation in soil and soilless systems under controlled conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10254, https://doi.org/10.5194/egusphere-egu25-10254, 2025.
In the rhizosphere, all transport processes considered fundamental in regulating resource availability and accessibility for plants and microorganisms are controlled by water retention and its temporal dynamics in the soil pore space, the rhizosphere liquid architecture (RLA). As the soil dries, root water and nutrient uptake becomes increasingly limited as the cross-sectional area and connectivity of the pore water declines. At the same time, diffusive transport ceases, negatively affecting root exudate transport and limiting microbial activity as enzyme diffusion and activity drop. The extent to which soil structural and biological processes influence local water retention and, in turn, related transport processes in the rhizosphere remains a challenging task. This study aimed to elucidate the effect of root growth and extracellular polymeric substances (EPS) on soil water retention in the rhizosphere of maize. High-resolution X-ray tomography was used to capture gradients in water distribution as a function of rhizosphere age and distance from the root surface. This combination of techniques allows distinguishing between soil structure versus primarily biologically induced modification. This study is a step toward a better understanding of the feedbacks between plants, microorganisms, and soil in controlling rhizosphere transport properties in this complex process aimed at optimizing resource availability and acquisition.
How to cite: Benard, P., Duddek, P., Stoll, F., Waldner, L., Kirchgessner, N., Lovric, G., and Carminati, A.: Rhizosphere Liquid Architecture, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11631, https://doi.org/10.5194/egusphere-egu25-11631, 2025.
Soil moisture content is a critical factor in the hydrological cycles of terrestrial ecosystems, especially in sandy environments. The spatial variation in soil water content is influenced by both dynamic and static factors. To understand the ecohydrology of desert environments, a detailed analysis of the vadose zone and topsoil in coastal dunes is essential. This study focuses on the soil hydrology of coastal mini-dunes (Nabkhas) in the Al-Hail North area of Oman, particularly examining moisture redistribution following a 13 mm rainfall event. The area, characterized by a sabkha landform with a shallow water table (approximately 1.4 meters below the surface), is interspersed by an array of Nabkhas. The length and height of three Nabkhas (N1, N2, and N3) were measured. Native plants were present in all Nabkhas: Haloxylon salicornicum in N1 (alive) and N3 (dead), and Salvadora persica in N2. Soil samples were collected from the interdune and Nabkha cores for grain size analysis. Decagon EC-05 sensors were installed at depths of 0 and 20 cm in the vertical profiles of N1, N2, and N3 to monitor diurnal variations in volumetric water content (ϴv).
A significant increase in ϴv in the top sensor immediately after the rain event was detected, while the bottom sensor showed a minimal increase over time. The top sensor's ϴv peaked at 0.1 m³/m³ on the last day of the rain event, then decreased to 0.054 m³/m³ after 8 days due to evaporation. The bottom sensor's ϴv reached a maximum of 0.58 m³/m³ on the final recording day. The spatial and temporal variation in ϴv is also influenced by vapor condensation from humid air and around native shrubs. High moisture content in the top layers of dunes significantly impacts vegetation patterns.
Another field investigation examined soil moisture variability using excavated profiles at four locations, including three sites under Nabkhas and a vegetation-free control plot. Analysis of volumetric water content demonstrated clear moisture stratification throughout the profiles. Near-surface soil layers showed minimal moisture levels, consistent with the residual water content (θr) typical in desert sandy soils. Moving downward through the profile, a significant increase in moisture content was detected, with lower horizons reaching near-saturation conditions (θs). This enhanced water retention in deeper layers was associated with both finer soil textures and water table influence. Such moisture-rich deeper soil zones appear to provide continuous capillary water movement to Nabkha vegetation root systems, enabling water redistribution throughout the soil-vegetation-atmosphere interface.
This study contributes to the conservation/restoration of desert vegetation and understanding the resilience of small-scale soil-water-plant ecosystems in arid regions. Further research on soil properties, water availability, and microclimate close to Nabkhas is necessary better to comprehend plant distribution and functioning in these landforms.
How to cite: Al Shukaili, A., Kacimov, A., Al Ismaili, S., Al Ghabshi, M., and Al Mamari, H.: Exploring the Hidden Interplay: Moisture and Vegetation Dynamics in the Nabkhas of Omani Coastal Dunes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12041, https://doi.org/10.5194/egusphere-egu25-12041, 2025.
It is commonly thought that plastic responses of root hydraulics and morphology to water availability have evolved to help plants face the heterogeneous soil water availability under unpredictable climatic conditions. However, quantifying these responses is an experimental challenge, as water uptake is continuously affecting root environment. The objective of this study is to investigate the structural and functional plasticity of roots under soil water heterogeneity from the plant down to the organ scales. We developed a novel rhizotron platform comprising 15 independent rhizotrons, each equipped with 9 hydraulically isolated compartments (three rows × three columns) and individual control units that allow for imposing constant spatial moisture patterns or differing water potentials in each compartment while monitoring local water consumption with minute time resolution and tracking root growth and development. A trial was made in which maize plants (cv. B104) grew in the rhizotron platform during four weeks at constant and homogeneous water potential, followed by a fifth week during which three water potentials were imposed. Morphological and hydraulic root responses to these different levels of water availability have been observed using manual root annotation and continuous leaf psychrometer measurements. These results allowed us to compute the elongation of main and lateral roots and real-time changes of the transpiration and local water consumption. This platform will be instrumental to dissect the complex response of maize plants in heterogeneous and variable soil water environments.
How to cite: Wei, T.-J., Draye, X., and Javaux, M.: A novel rhizotron platform to evaluate root plastic responses to soil water heterogeneity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11748, https://doi.org/10.5194/egusphere-egu25-11748, 2025.
Of the earth’s 840 million hectares are of soil, roughly 683 million hectares are saline, and 157 million hectares are saline-sodic. The direct impact of an osmotic stress to plant growth in salt affected soils is well known. Plant roots in salt-affected soils often have morphological changes, and ionic imbalance that interfere with nutrient uptake. In saline-sodic soils, decreased physical stability is typical, likely driving greater penetration resistance and decreased soil aeration. This could reduce root growth, but research is missing that directly links these measurements of physical behaviour to plant growth. The present study explores these effects in repacked cores of sandy loam and clay loam soils in saline-sodic (NaCl,1.76 g kg-1 soil) or saline (KCl, 2.25 g kg-1 soil) conditions. Different physical conditions of light (50 kPa) and high (200 kPa) compaction stresses, and wet (-5 kPa) and drier (-50 kPa) water potentials were imposed under controlled conditions. Physical data of compression characteristics, bulk density, water content, air-filled porosity, and penetration resistance were measured on the soil cores. Wheat (salt intolerant) and barley (salt tolerant) were grown in the cores and the lengths of their seedling roots were measured 48 hours after sowing in a rapid growth screen. This study investigates the comparative impacts of saline-sodic and saline soils on soil physical properties and the subsequent effects on barley and wheat root growth. Saline-sodic soil exhibited significantly greater penetration resistance, ranging from 0.58 to 2.73 MPa, compared to the control range of 0.62 to 1.70 MPa. In contrast, saline soil demonstrated less penetration resistance, with a maximum value of 1.84 MPa. Additionally, air-filled porosity in saline-sodic soil decreased to 19%, indicating reduced oxygen availability, while saline soil retained higher aeration (43%), surpassing the control value (34%).
These alterations in soil properties significantly influenced root growth. Barley root elongation was more strongly linked to physical changes, while wheat root growth was adversely affected by both physical and chemical alterations due to its lower salt tolerance. In saline-sodic soil, barley and wheat root elongation were reduced to 32% and 20% of the control, respectively, primarily due to increased penetration resistance. A reduction in air-filled porosity further restricted root growth to 46.7% for barley and 30.6% for wheat. Conversely, the lower penetration resistance in saline soil supported higher root elongation, reaching 82.8% for barley and 63.6% for wheat in comparison to the control. Our analysis with concepts from the least limiting water range indicate that soil physical constraints exacerbate root growth restrictions in saline-sodic soils.
How to cite: Elsakloul, F.: Saline-sodicity and soil physical impact on root growth, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14146, https://doi.org/10.5194/egusphere-egu25-14146, 2025.
The role of root mucilage in facilitating water uptake during soil drying has been studied for decades. Recently, we demonstrated that mucilage slows the dissipation of water potential in the rhizosphere of actively transpiring plants. While these findings provide new insights into how mucilage maintains the hydraulic continuity between soil and roots under drying conditions, the interaction between mucilage and soil texture remains underexplored.
We used two cowpea genotypes with contrasting mucilage production, grown in two distinct soil textures (coarse and fine), and measured physiological and morphological parameters during and after a dry-down experiment. We hypothesized that mucilage would have a greater role in coarse-textured soils due to its ability to form polysaccharide networks within larger soil pores, enhancing hydraulic connectivity during drying.
Although shoot biomass did not differ between genotypes and soil textures, root morphological analysis revealed significant adaptations to soil texture. The low-mucilage genotype developed a root system twice as long in sand compared to loam, while the high-mucilage genotype showed only a slight increase in root length in sand. Normalized transpiration rates and leaf water potential were similar between genotypes in loam. However, in sand, the high-mucilage genotype maintained relatively lower leaf water potentials (≤ -1.0 MPa), while the low-mucilage genotype closed its stomata at less negative leaf water potentials (≤ -0.6 MPa). These results underscore the critical role of soil texture in shaping plant drought responses and highlight the importance of mucilage in enhancing water uptake in coarse soils.
The ability of mucilage to maintain hydraulic continuity during soil drying is particularly beneficial in coarse-textured soils, where larger pores cause steep decline in water potential in the rhizosphere. The contrasting strategies observed in the two cowpea genotypes—root system elongation versus mucilage-driven water retention—highlight the diverse adaptations plants employ to cope with edaphic stress.
How to cite: Abdalla, M. and Ahmed, M.: Soil texture shapes plant adaptation to edaphic stress, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15272, https://doi.org/10.5194/egusphere-egu25-15272, 2025.
Potato is one of the most important food crops in the world. It is grown in many countries in different climates, including temperate, tropical, and subtropical regions. Yet its cultivation is hampered by low soil fertility, pests and diseases, and inadequate, good-quality seed tubers. To improve the quality and production of potatoes, it is necessary to develop the potato cultivation technology. The aeroponic system is a way to grow food without soil and save water. Growing tubers has its limitations and challenges to producing good quality seed potatoes. The soilless system allows for a higher growth rate and healthy potato tubers, using a small amount of water. Production is not affected by weather or seasonal adverse effects such as hot, dry, cold, or windy weather. Cultivation can be carried out all year round and yields disease-free potatoes in larger quantities.
Our experiment was set up in the Aeroponics System of the University of Debrecen Faculty of Agricultural and Food Sciences and Environmental Management, Institute of Water and Environmental Management. Two Hungarian potato (Solanum tuberosum L.) cultivars, Démon and Botond, were tested in this experiment. We planted 28-day-old, in vitro-raised, properly hardened, 8-10 cm high microplants in the growing units. The nutrient solution, temperature, humidity, and light conditions were set according to the needs of the plants based on literature data. After a few days, the plants' root system began to develop, with a 100 percent survival rate, the plants grew rapidly, and on the 58th day in the system, the beginnings of flowers appeared. During their development, we examined the height, number of leaves, stem thickness, photosynthetic activity, the chlorophyll-carotenoid content of the plants, and we also examined the characteristics of the individual growth stages with the help of active GIS (LiDAR).
This manuscript provides insight into the potential use of aeroponics for the development of agro techniques for seed potato production. Differences were found between the cultivars in the examined parameters. Démon is a cultivar with stronger stems and greater stem strength, which started flowering earlier but is more sensitive to the composition of the nutrient solution. The Botond cultivar is more elongated in the direction of the light. Aeroponic systems are suitable for growing seed potatoes.
The research presented in the article was carried out within the framework of the Széchenyi Plan Plus program, with support from the RRF 2.3.1 21 2022 00008 project.
How to cite: Kovács, G., Szűcs, I., Pásztor, D., Nagy, A., and Tamás, J.: Investigations of the growth and development of seed potatoes under aeroponic conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15440, https://doi.org/10.5194/egusphere-egu25-15440, 2025.
Plant development strongly depends on the water and nutrient uptake by the evolving root system, the carbon uptake and assimilation in the leaves, as well as the water, solute and carbon transport inside the plant. The mechanistic functional-structural plant model CPlantBox enables simulations of the dynamic plant and soil systems, and therefore the analysis of feedback loops between water and carbon fluxes as well as root-soil interface processes such as water and solute uptake or rhizodeposition. Such models are a crucial tool to evaluate the sustainability of future phenotype-environment-management combinations, as well as to enhance plant breeding efforts and to analyze the impact of future climate scenarios. Therefore, CPlantBox serves as a powerful platform for advancing sustainable agricultural management strategies .
The open-source model CPlantBox has been developed over the last fifteen years starting from a pure structural root model (Leitner et al. 2010) developing to a functional-structural root architecture model (Schnepf et al. 2018), towards a more holistic functional structural plant model (Giraud et al. 2023, Zhou et al. 2020). Today, CPlantBox includes multiple functional modules describing water and carbon fluxes within the plant, including a photosynthesis model, as well as various dynamic rhizosphere modules that are described by 1D axisymmetric systems of partial differential equations (PDE) around root segment that interact with 1D, 2D or 3D macroscopic soil models. The PDEs are solved with the open-source finite volume solver DuMux (Koch et al. 2021). In this work we describe CPlantBox by state-of-the art examples from various research projects specifically focusing on its functional modules, and presenting its modelling framework which facilitates further model development.
References
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How to cite: Leitner, D., Giraud, M., Schnepf, A., Pagel, H., and Vanderborght, J.: Plant Modeling with CPlantBox: Bridging Structure and Function , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17280, https://doi.org/10.5194/egusphere-egu25-17280, 2025.
