Chemical imaging of phosphorus dynamics in the rhizosphere

Wien

2014

S. 36

Artikel aus einer ZeitschriftUnselbständiges Werk

200190228

Phosphorus (P) is one of the most limiting nutrients to plant growth and crop yield. To increase P uptake, plants can actively solubilise P by releasing e.g. protons or organic anions. Innovative approaches for 2D chemical imaging of rhizosphere processes can be used to investigate the complex interactions of plant roots and soil. Diffusive gradients in thin films (DGT) combined with laser ablation – inductively coupled plasma mass spectrometry (LA-ICP-MS) allow for the 2D visualisation of the distribution of cationic and anionic solute species in the rhizosphere. Furthermore, pH-sensitive planar optodes can map the rhizophere pH. The aim of this work was the development and testing of a combined setup of DGT-LA-ICP-MS and pH-sensitive planar optodes to investigate biogeochemical processes controlling P solubility in the rhizosphere. This was achieved by simultaneous imaging of P, Al, Ca, Fe and pH to assess if P solubilisation is related to the dissolution of P sorption sites (Fe- and Al-(oxy)-ydroxides) and of soil P minerals such as Ca-, Fe-, Al-phosphates. To this end, a plant experiment using Triticum aestivum L., Fagopyrum esculentum L., and Lupinus albus L. on calcareous and non-calcareous soils was conducted. We show the applicability of simultaneous 2D chemical imaging of soluble Ca-, Fe-, and Al together with P using DGT-LA-ICP-MS as well as 2D mapping of plant induced pH-changes based on planar optodes. We conclude that this combined imaging approach offers great potential for investigating P depletion around roots, mineral dissolution due to root activities as well as plant induced pH-changes at sub-mm resolution.