Co-occurring increased phosphatase activity and labile P depletion in the rhizosphere of Lupinus angustifolius assessed with a novel, combined 2D-imaging approach

Hummel, Christina; Boitt, Gustavo; Santner, Jakob; Lehto, Niklas J.; Condron, Leo M.; Wenzel, Walter W.

doi:10.1016/j.soilbio.2020.107963

Cited by 36 publications

(13 citation statements)

References 50 publications

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“…Such a difference is not observed for the critical values of P-DGT which indicates-consistent with theory-that this soil test is less influenced by soil properties. The critical values of P deficiency derived in our study for P-CAL (44.9 mg kg -1 for barley, 24.6 mg kg -1 for all crops, Table 2) compare well with the boundary between the classes ''low'' and ''adequate'' (46 mg kg -1 ) of the Austrian guidelines for fertilization (Bundesministerium fu ¨r Land-und Forstwirtschaft, Umwelt und Wasserwirtschaft 2017; Jordan-Meille et al 2012).…”

Section: Critical Values Below Which P Deficiency Occurssupporting

confidence: 75%

“…For fast-growing crops, P diffusion may be also limited by low rates of P desorption from the solid phase (Smolders et al 2021). Diffusion and/or desorption-limited P uptake is further supported by direct observations using chemical imaging consistently showing depletion of total and available P in the rhizosphere of wheat and numerous other crops even in weakly to moderately weathered soils (Hoefer et al 2015;Hummel et al 2021;Santner et al 2012;Kreuzeder et al 2018;Wagner et al 2020). Together, this provides strong evidence that P availability is generally limited by diffusion and re-supply from the solid phase.…”

Section: Critical Values Below Which P Deficiency Occursmentioning

confidence: 92%

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Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Hill

Santner

Spiegel

et al. 2021

Nutr Cycl Agroecosyst

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Soil P testing has been widely used to predict crop yields, P uptake, and fertilizer demands in agriculture. Diffusive gradients in thin films (DGT) provides a zero-sink soil P test which mimics diffusion-controlled plant uptake and has previously been found to predict P availability to crops better than conventional quantity-based P tests in highly weathered Australian, though not in European soils. Here we tested the performance of DGT and the Austrian and German standard P quantity test calcium acetate lactate (CAL) to explain the variation of crop yield and P uptake response of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) in long-term P fertilization experiments at four different sites in eastern Austria. Phosphorus extracted with DGT (P-DGT) and CAL (P-CAL) correlated well in similar soils but not across sites with large variation in soil and site properties such as carbonate equivalent and water availability. The predictive power of DGT for barley (R2 = 0.42) and wheat grain yield (R2 = 0.32), and P uptake in wheat grains (R2 = 0.36) was clearly superior to that of the CAL, and less dependent on soil properties. The better performance of DGT compared to the quantity test is consistent with diffusion-limited P uptake in the water-limited cultivated soils of eastern Austria. The critical values of P deficiency derived from the Mitscherlich-type fits for barley and wheat at 80% relative yield are 64.9 and 26.2 µg L−1, respectively, consistent with differential P demands of the crops.

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Section: Critical Values Below Which P Deficiency Occurssupporting

confidence: 75%

Section: Critical Values Below Which P Deficiency Occursmentioning

confidence: 92%

Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Hill

Santner

Spiegel

et al. 2021

Nutr Cycl Agroecosyst

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“…As a result of the rapid protonation of phosphoryl groups, phosphate-monoester anions have increased electrophilicity, which allows them to react more quickly with substrates in contrast to phosphate-diester anions (Hengge, 2005 ). Experimental evidence concerning the co-occurrence of phosphatase activity and the P depletion zone has been obtained up to a distance of 2–4 mm from the root surface (Nuruzzaman et al, 2006 ; Hummel et al, 2021 ). Phosphatase activity near the root surface reduces the concentration of P o substrate compared with the surrounding soil (Burns et al, 2013 ).…”

Section: Effects Of Root Exudation On Phosphatase Activitymentioning

confidence: 99%

Two-Phase Conceptual Framework of Phosphatase Activity and Phosphorus Bioavailability

et al. 2022

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The activity of extracellular phosphatases is a dynamic process controlled by both plant roots and microorganisms, which is responsible for the mineralization of soil phosphorus (P). Plants regulate the availability of soil P through the release of root mucilage and the exudation of low-molecular weight organic acids (LMWOAs). Mucilage increases soil hydraulic conductivity as well as pore connectivity, both of which are associated with increased phosphatase activity. The LMWOAs, in turn, stimulate the mineralization of soil P through their synergistic effects of acidification, chelation, and exchange reactions. This article reviews the catalytic properties of extracellular phosphatases and their interactions with the rhizosphere interfaces. We observed a biphasic effect of root metabolic products on extracellular phosphatases, which notably altered their catalytic mechanism. In accordance with the proposed conceptual framework, soil P is acquired by both plants and microorganisms in a coupled manner that is characterized by the exudation of their metabolic products. Due to inactive or reduced root exudation, plants recycle P through adsorption on the soil matrix, thereby reducing the rhizosphere phosphatase activity. The two-phase conceptual framework might assist in understanding P-acquisition (substrate turnover) and P-restoration (phosphatase adsorption by soil) in various terrestrial ecosystems.

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“…Although orthophosphate itself is generally not reduced in submerged/rice paddy soils, P i tends to be mobilized under anaerobic conditions when precipitated Fe(III) species that bind with P i are transformed to soluble Fe(II) . With regard to the fraction of P org , microbial release and plant release of extracellular enzymes (phosphatase) catalyze the hydrolysis and mineralization of unavailable P org to soluble P i . − The main source of alkaline phosphatase activity in soil is from bacteria/archaea, whereas acid phosphatases can derive from plants, fungi, and bacteria. , …”

Section: Introductionmentioning

confidence: 99%

Combining Multiple High-Resolution In Situ Techniques to Understand Phosphorous Availability Around Rice Roots

Fang

Williams²,

Zhang

et al. 2021

Environ. Sci. Technol.

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Resolving chemical/biological drivers of P behavior around lowland/flooded rice roots remains a challenge because of the heterogeneity of the plant–soil interactions, compounded by sampling and analytical constraints. High-spatial-resolution (sub-mm) visualization enables these processes to be isolated, characterized, and deciphered. Here, three advanced soil imaging systems, diffusive gradients in thin-film technique coupled with laser ablation-ICPMS (DGT-LA-ICPMS), O2 planar optode, and soil zymography, were integrated. This trio of approaches was then applied to a rice life cycle study to quantify solute-P supply, through two dimensions, in situ, and low-disturbance high-resolution (HR) chemical imaging. This allowed mechanisms of P release to be delineated by O2, Fe, and phosphatase activity mapping at the same scale. HR-DGT revealed P depletion around both living and dead rice roots but with highly spatially variable Fe/P ratios (∼0.2–12.0) which aligned with changing redox conditions and root activities. Partnering of HR-DGT and soil zymography revealed concurrent P depletion and phosphatase hotspots in the rhizosphere and detritusphere zones (Mantel: 0.610–0.810, p < 0.01). This close affinity between these responses (Pearson correlation: −0.265 to −0.660, p < 0.01) cross-validates the measurements and reaffirms that P depletion stimulates phosphatase activity and Porg mineralization. The μ-scale biogeochemical landscape of rice rhizospheres and detritusphere, as documented here, needs greater consideration when implementing interventions to improve sustainable P nutrition.

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Co-occurring increased phosphatase activity and labile P depletion in the rhizosphere of Lupinus angustifolius assessed with a novel, combined 2D-imaging approach

Cited by 36 publications

References 50 publications

Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Two-Phase Conceptual Framework of Phosphatase Activity and Phosphorus Bioavailability

Combining Multiple High-Resolution In Situ Techniques to Understand Phosphorous Availability Around Rice Roots

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