Physics and hydraulics of the rhizosphere network

Benard, Pascal; Zarebanadkouki, Mohsen; Carminati, Andrea

doi:10.1002/jpln.201800042

Cited by 25 publications

(37 citation statements)

References 23 publications

(32 reference statements)

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“…The effect of mucilage on nutrient diffusion can be explained by two main processes: (i) when soil dries, mucilage keeps the rhizosphere wet due to its high water‐holding capacity (McCully and Boyer, 1997; Carminati et al, 2010) and therefore maintains the diffusive transport of nutrients at a higher rate, and (ii) mucilage alters the spatial configuration of the liquid phase and increases its connectivity in drying soil due to its unique properties (water sorption, high viscosity, and low surface tension) (Carminati et al, 2017; Benard et al, 2018). The latter one was the focus of the experiments performed herein to monitor the diffusion coefficient of Cs.…”

Section: Discussionmentioning

confidence: 99%

“…Since the soil water content was equal, the difference in diffusion coefficient can be safely assigned to change in spatial distribution of liquid phase within the soil pore spaces. The increase in viscosity of the liquid phase due to the presence of mucilage as the soil dries allows water (liquid phase) to stay connected and aid the diffusion of Cs through a continuous film within the pore space (Carminati et al, 2017; Benard et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Mucilage in the rhizosphere could affect diffusion of nutrients in two ways (Fig. 1): (i) mucilage increases the water‐holding capacity of the rhizosphere, which results in a larger cross‐sectional area of the liquid phase at a given soil water potential, or (ii) mucilage may alter the spatial configuration of the liquid phase during soil drying by preventing the capillary breakup of the liquid phase (Carminati et al, 2017; Benard et al, 2018). Root mucilages from different plant species share some fundamental properties.…”

Section: Conceptual Model: the Effect Of Mucilage On Nutrient Availabmentioning

confidence: 99%

“…Besides its intrinsic hygroscopic nature, mucilage lowers the surface tension at the gas-liquid interface and increases the viscosity of the soil solution (Read and Gregory, 1997). The interplay between water absorption, surface tension, and viscosity was shown to alter the spatial configuration of the liquid phase in drying soil (Carminati et al, 2017;Benard et al, 2018Benard et al, , 2019.…”

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confidence: 99%

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Mucilage Facilitates Nutrient Diffusion in the Drying Rhizosphere

Zarebanadkouki

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Benard

et al. 2019

Vadose Zone Journal

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Core Ideas Our aim was to test whether mucilage promotes diffusion of nutrients in dry soil. Mucilage favors transport of nutrients in drying soil and their uptake by plant. Mucilage increases the soil moisture in the rhizosphere as soil dries. Mucilage maintains the connectivity of liquid phase in the rhizosphere as soil dries. Despite detailed investigations of its distinct biochemical properties and their effects on the availability of nutrients for plants, the biophysical aspects of the rhizosphere, particularly the effect of mucilage on the transport of water and nutrients, are poorly understood. The aim of this study was to investigate the effect of mucilage on the diffusion of nutrients and consequently their transport through the rhizosphere into the plant roots. Phosphor imaging technique determined the temporospatial distribution of 137Cs in a model rhizosphere (a sandy soil mixed with chia seed (Salvia hispanica L) mucilage. The observed profiles of activities were used to estimate the diffusion coefficient of K in soils. A diffusion–convection equation was numerically solved to predict the transport of K and its uptake by a single plant root in drying soil. The results suggest that mucilage (i) keeps the rhizosphere wet and (ii) maintains the connectivity of the liquid phase in drying soil. In these ways, mucilage moderates the drop in diffusive transport. The modeling results showed that the presence of mucilage in the rhizosphere (i) prevents depletion of nutrients in soils with a low nutrient concentration in the soil solution and (ii) delays the risk of nutrient and/or salt accumulation in the vicinity of the root in soils with a high concentration nutrient and/or salt the soil solution. In conclusion, mucilage appears to mitigate the risk of nutrient deficiency and salinity stress as it enhances the diffusive transport in drying soil. In this way, mucilage may favor the transport of nutrients within the rhizosphere and their uptake by plant roots in drying soil.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Conceptual Model: the Effect Of Mucilage On Nutrient Availabmentioning

confidence: 99%

mentioning

confidence: 99%

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Mucilage Facilitates Nutrient Diffusion in the Drying Rhizosphere

Zarebanadkouki

Fink

Benard

et al. 2019

Vadose Zone Journal

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“…This may be quite astonishing since McCully and Boyer (1997) found that free mucilage releases most of its water already at very little suctions. However, we expect that mucilage—when bound to the soil surface—acts in a very different way compared to free mucilage: parts of it are sorbed to the soil surface creating a spider‐web like structure ( Brax et al., 2017, 2018; Benard et al., 2019;) that can hold water also at low suctions opposed to the case of free mucilage. It was found that for fine soils little amount of mucilage was sufficient to increase residual water content, while for very coarse soils 0.8% of dry mucilage per dry soil was required.…”

Section: Pore Scale Hydraulic Processes Affected By Mucilagementioning

confidence: 99%

Perspectives from the Fritz‐Scheffer Awardee 2017. How mucilage affects soil hydraulic dynamics#

Kroener

2021

J. Plant Nutr. Soil Sci.

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Take home message Mucilage is a hydrogel exuded at root tips, which can hold large amounts of water but turns hydrophobic once dried. It is very challenging to understand the interplay of these opposite mechanisms and to incorporated them into hydraulic soil models. My summary of experimental and modelling approaches and observations at various scales is meant to help improving soil–plant water dynamic models and may also be helpful when water dynamics need to be considered in biogeochemical rhizosphere models.

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Differences in mucilage properties and stomatal sensitivity of locally adapted Zea mays in relation with precipitation seasonality and vapour pressure deficit regime of their native environment

Berauer,

Akale,

Schweiger

et al. 2023

Plant Direct

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With ongoing climate change and the increase in extreme weather events, especially droughts, the challenge of maintaining food security is becoming ever greater. Locally adapted landraces of crops represent a valuable source of adaptation to stressful environments. In the light of future droughts—both by altered soil water supply and increasing atmospheric water demand (vapor pressure deficit [VPD])—plants need to improve their water efficiency. To do so, plants can enhance their access to soil water by improving rhizosphere hydraulic conductivity via the exudation of mucilage. Furthermore, plants can reduce transpirational water loss via stomatal regulation. Although the role of mucilage and stomata regulation on plant water management have been extensively studied, little is known about a possible coordination between root mucilage properties and stomatal sensitivity as well as abiotic drivers shaping the development of drought resistant trait suits within landraces. Mucilage properties and stomatal sensitivity of eight Mexican landraces of Zea mays in contrast with one inbred line were first quantified under controlled conditions and second related to water demand and supply at their respective site of origin. Mucilage physical properties—namely, viscosity, contact angle, and surface tension—differed between the investigated maize varieties. We found strong influences of precipitation seasonality, thus plant water availability, on mucilage production (R2 = .88, p < .01) and mucilage viscosity (R2 = .93, p < .01). Further, stomatal sensitivity to increased atmospheric water demand was related to mucilage viscosity and contact angle, both of which are crucial in determining mucilage's water repellent, thus maladaptive, behavior upon soil drying. The identification of landraces with pre‐adapted suitable trait sets with regard to drought resistance is of utmost importance, for example, trait combinations such as exhibited in one of the here investigated landraces. Our results suggest a strong environmental selective force of seasonality in plant water availability on mucilage properties as well as regulatory stomatal effects to avoid mucilage's maladaptive potential upon drying and likely delay critical levels of hydraulic dysfunction. By this, landraces from highly seasonal climates may exhibit beneficial mucilage and stomatal traits to prolong plant functioning under edaphic drought. These findings may help breeders to efficiently screen for local landraces with pre‐adaptations to drought to ultimately increase crop yield resistance under future climatic variability.

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Physics and hydraulics of the rhizosphere network

Cited by 25 publications

References 23 publications

Mucilage Facilitates Nutrient Diffusion in the Drying Rhizosphere

Mucilage Facilitates Nutrient Diffusion in the Drying Rhizosphere

Perspectives from the Fritz‐Scheffer Awardee 2017. How mucilage affects soil hydraulic dynamics#

Differences in mucilage properties and stomatal sensitivity of locally adapted Zea mays in relation with precipitation seasonality and vapour pressure deficit regime of their native environment

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