Rainfall reduction impacts rhizosphere biogeochemistry in eucalypts grown in a deep Ferralsol in Brazil

Pradier Céline, Hinsinger Philippe, Laclau Jean-Paul, Bouillet Jean-Pierre, Guerrini Iraê Amaral, Gonçalves José Leonardo M., Asensio Verónica, Abreu-Junior Cassio Hamilton, Jourdan Christophe. 2017. Rainfall reduction impacts rhizosphere biogeochemistry in eucalypts grown in a deep Ferralsol in Brazil. Plant and Soil, 414 (1) : 339-354.

https://doi.org/10.1007/s11104-016-3107-7

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

	Version Online first - Anglais Accès réservé aux personnels Cirad Utilisation soumise à autorisation de l'auteur ou du Cirad. Pradier 2017_PS_Rainfall reduction impacts rhizosphere biogeochemistry in eucalypts grown in a deep Ferralsol in Brazil.pdf Télécharger (955kB) \| Demander une copie
	Version publiée - Anglais Accès réservé aux personnels Cirad Utilisation soumise à autorisation de l'auteur ou du Cirad. art%3A10.1007%2Fs11104-016-3107-7.pdf Télécharger (1MB) \| Demander une copie

Quartile : Q1, Sujet : AGRONOMY / Quartile : Q1, Sujet : PLANT SCIENCES / Quartile : Q1, Sujet : SOIL SCIENCE

Résumé : Background and aims Comparing root functioning under contrasting rainfall regimes can help assessing the capacity of plant species to cope with more intense and frequent drought predicted under climate change context. While the awareness of the need to study the whole root system is growing, most of the studies of root functioning through rhizosphere analyses have been restricted to the topsoil. Our study aimed to assess whether the depth in the soil and the rainfall amount affect root functioning, and notably the fate of nutrients within the rhizosphere. Methods We compared pH and nutrient availability within the rhizosphere and bulk soil along a 4-m deep soil profile in a 5-year-old eucalypt (Eucalyptus grandis) plantation under undisturbed and reduced rainfall treatments. Results The exchangeable K concentration and the pH of the bulk soil were not influenced by the reduced rainfall treatment. By contrast, the H3O+ concentration in the rhizosphere was significantly greater than that of the bulk soil, only in the reduced rainfall plot. The concentrations of exchangeable K in the rhizosphere were significantly larger than those of the bulk soil in both treatments but this difference was higher in the reduced rainfall plot, notably below the depth of 2 m. Both exchangeable K and H3O+ concentration significantly increased within the rhizosphere in the reduced rainfall treatment at soil depth down to 4 m. Conclusions The amount of K brought to the roots by mass flow was estimated and could not explain the observed increase in exchangeable K concentration within the rhizosphere. A more likely explanation was root-induced weathering of K-bearing minerals, partly related to enhanced rhizosphere acidification. Our results demonstrate that root functioning can be considerably altered as a response to drought down to large depths.

Mots-clés Agrovoc : Eucalyptus grandis, changement climatique, sécheresse, rhizosphère, système racinaire, transport des substances nutritives, potassium, adaptation aux changements climatiques, pluviométrie, profondeur, acidification