in situ visualization of phosphorus mobilizing processes in the rhizosphere of zea mays l. in the field - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Conference Papers Year : 2021

in situ visualization of phosphorus mobilizing processes in the rhizosphere of zea mays l. in the field

Abstract

Understanding phosphorus (P) dynamics in the soil-plant system is crucial for sustainable crop production. To investigate the effect of root hairs and soil texture on the spatial distribution and intensity of P mobilizing processes, we applied 2D chemical imaging methods to visualize soil pH (planar optodes), acid phosphatase activity (zymography) and labile P and Mn fluxes (Diffusive Gradients in Thin films) in the rhizosphere of two maize genotypes (wildtype WT and root hair defective mutant rth3) grown in a field trial in two repacked soil substrates (loam, sand) in Bad Lauchstädt, Germany (central experimental platform SPP2089 field trial). Twelve custom-designed root windows (60x60 cm) installed in the field allowed to non-destructively apply these imaging techniques at maize growth stage BBCH 59 (end of tassel emergence). Image analysis revealed a strong patchiness for pH and labile P while acid phosphatase activity and Mn flux were more homogenously distributed along the roots. Acidification was more pronounced in sand due to lower P availability and lower buffer capacity compared to loam. Acid phosphatase activity in the rhizosphere was similar for both genotypes and substrates. P flux showed no clear trend and depletion zones were rather indicative. Irrespective of genotype and texture, elevated P flux was observed at root tips. Acidification was stronger around young growing tips and within the elongation zone than at older sections which was even more pronounced for WT and co-localized with high phosphatase activity, P and Mn flux. Our results suggest that proton extrusion was linked to root growth and created a pH optimum for P solubility, P uptake and acid phosphatase activity, i.e., transformation of organic P to available phosphate especially at the tips and the elongation zone which are the major sites of P uptake. Combined with the generally higher P availability in loam and the higher absorption surface of root hairs, these rhizosphere processes jointly contributed to a more efficient P uptake of WT compared to rth3 and better performance in loam compared to sand.
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Dates and versions

hal-03638460 , version 1 (12-04-2022)

Identifiers

  • HAL Id : hal-03638460 , version 1

Cite

C. Hummel, N. Bilyera, Gabrielle Daudin, X. Zhang, M. Santangeli, et al.. in situ visualization of phosphorus mobilizing processes in the rhizosphere of zea mays l. in the field. Eurosoil 2021, Aug 2021, Geneva, Switzerland. pp.O030. ⟨hal-03638460⟩
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