Mobilization of aluminium and magnesium by roots of banana (Musa spp.) from kaolinite and smectite clay minerals |
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| Institution: | 1. Department of Agricultural Sciences, University of Naples Federico II, Via Università, 100, 80055 Portici, NA, Italy;2. CRISP - Interdepartmental Research Centre on the Earth Critical Zone, University of Naples Federico II, Via Università, 100, 80055 Portici, NA, Italy;3. CNR - ISAFOM, Via Patacca, 85, 80056 Ercolano, NA, Italy;1. Université de Poitiers/CNRS, UMR 7285 IC2MP, équipe HydrASA, Bat. B8 rue Albert TURPAIN, TSA 51106, 86073 Poitiers CEDEX 9, France;2. AREVA, Business Group Mines, R&D Department, Tour AREVA, 1 place Jean Millier, 92084 Paris La Défense, France;1. UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia;2. Centre Européen de Recherche et d''Enseignement des Géosciences de l''Environnement (CEREGE), Aix-Marseille Université, Aix en Provence, France;1. SUBATECH, UMR 6457, IN2P3/CNRS/EMN/Université de Nantes, 4, rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3, France;2. LPG-NANTES, UMR 6112 CNRS, 44322 Nantes, France |
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| Abstract: | Banana plants (Musa spp.) are very sensitive to Al, which is mobilized in acid soil conditions. These plants may, however, contribute to their own intoxication because their roots can excrete protons in large quantities. The authors studied the mobilization of Al by banana roots from clay minerals in experimental designs exacerbating the root–mineral contact. The plants were grown on agarose-gel or sand substrates previously mixed with smectite (montmorillonite) and kaolinite as sole source of Al. The pH and the ion concentrations in the aqueous and exchangeable phases of the substrates were determined as concentrations of Al, Ca, Mg and K in plants. In both agarose and sand substrates, pH significantly decreased in the close vicinity of roots, relative to the bulk substrate. This root-induced acidification involved a preferential mobilization of Al in kaolinite substrates and of Mg in smectite substrates, and thereby a significant plant uptake of Al and Mg from these respective substrates. Root-induced weathering of kaolinite and montmorillonite thus suggests that the mobilization of, respectively, Al and Mg are the limiting steps in the dissolution of these respective minerals, just as demonstrated in previous chemical weathering studies. |
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