Home / Conferences / Frontiers of Potassium Science, Rome, 2017 Frontiers of Potassium Science Rome 2017 Frontiers of Potassium Science Conference Presentations - Sustainable Intensification Presentations - 4R Source Presentations - 4R Rate Presentations - 4R Time Presentations - 4R Place Presentations - Connecting Frontier Science to Frontier Practice Presentations - Conclusion and Next Steps Posters Conference Proceedings Contenu des liens YouTube Root traits and rhizosphere characteristics determining potassium acquisition from soils icon-email icon-facebook icon-linkedin icon-twitter 27 Jan 2017 4R Place - Root traits and rhizosphere characteristics determining potassium acquisition from soils Philippe Hinsinger, INRA Plants acquire K+ ions from the soil solution, and this small and dynamic pool needs to be quickly replenished by the other soil pools, either the exchangeable pool via desorption of K adsorbed onto clay minerals and organic matter, or the nonexchangeable pool via weathering of K-bearing silicates. Because of these chemical interactions with soil solid phases, K+ concentration is kept low, restricting its mobility. Mass-flow therefore only partly contributes to K+ transfer to the root surface, and K+ depletion occurs as a consequence of K+ uptake by roots, which is the driving force for the diffusion of K+ in the rhizosphere. Because of this restricted mobility of K in soils, plants have evolved efficient strategies of root foraging. Therefore, root traits related to root system architecture (root angle, branching, depth), root length and growth, as well as root hairs and mycorrhiza-related traits play an important role in determining the capacity of plants to cope with the poor mobility of soil K, as well as its distribution in the whole soil profile, with potential significant contribution of subsoil K in many soils. Another consequence of the root-induced depletion of K+ is a shift of the exchange equilibria, enhancing the desorption of exchangeable K, as well as the release of nonexchangeable, interlayer K from micaceous minerals in the rhizosphere. This means that both of these pools can be bioavailable, provided that plant roots can take up significant amounts of K at low K+ concentrations in the soil solution (in the micromolar range). This is thus an important physiological root trait determining the acquisition efficiency of plants. Besides, roots can significantly acidify their environment or release large amounts of exudates, these two processes ultimately promoting the dissolution of K-bearing silicates such as micas and feldspars in the rhizosphere, which contributes the mining strategy evolved by plants. There are thus a number of root or rhizosphere-related traits (either morphological or physiological) that determine the acquisition efficiency of crop species and genotypes. The aim of this paper is to provide a detailed overview of these.