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Impact of Na and K fertilization on Eucalyptus response to drought - integrative approach : S02T08

Favreau B., Denis M., Battie Laclau P., Franzol S.D., Labate C.A., Tomazello M., Chaix G.. 2013. In : Brasileiro Ana Christina Miranda (ed.), Fortes Ferreira Claudia (ed.), Fernandez Diana (ed.), Micheli Fabienne (ed.), Coelho Filho M.A. (ed.), Marraccini Pierre (ed.). Biotic and Abiotic Stress Tolerance in Plants: the Challenge for the 21st Century : Book of abstracts of the CIBA 2013. Brasilia : EMBRAPA, p. 21-22. Workshop on Biotic and Abiotic Stress Tolerance in Plants: the Challenge for the 21st Century, 2013-11-06/2013-11-08, Ilhéus-Bahia (Brésil).

Eucalyptus is a fast growing tropical species depending strongly on environment, soil fertility and water supply. Potassium fertilization improves drought resistance and growth performance, but world resources decline while cost increases. Moreover, climate changes are expected to alter precipitation frequency and intensity, with increasing period of dry season. Consequently, drought is likely to increase in tropical area, mainly in regions with water deficiency during dry season. Therefore, genetic researches must develop efficient varieties in term of water and mineral uses, to respond to worldwide sustainable system and extend plantation on marginal zones. The potassium role in plant water regulation has still to be elucidated, alone or in combination with other micronutrients. Interestingly, sodium can partially replace it in some species such as Eucalyptus. In this context, we aim to study the impact of mineral fertilization on the Eucalyptus response to drought. A long term field experiment was set up in 2010 in Itatinga (SP, Brazil) to study E. grandis response to partial rainfall exclusion crossed with fertilization. Integrative approaches are developed to measure the Eucalyptus response on different tissues. Here we present two combined approaches to discriminate 2 years-old trees leaves according to the 6 treatments applied: 100% or 65% H2O with +K, +Na or no fertilization. Near InfraRed Spectroscopy (NIRS) data were analyzed by using Partial Least Squares Discriminant Analysis. Our results showed leaf discrimination according to reduced and normal water supply, and secondly, to potassium, sodium fertilization and no fertilization. Fingerprinting metabolomic analysis (UPLC-Q-TOF-MS) data were analyzed by using univariate statistical analysis to select the most significant metabolites. Then Hierarchical Cluster Analysis and Principal Component Analysis were performed on the selected metabolites. As for NIRS, leaf samples were successfully discriminated according to the water treatments then to the fertilizations. Besides, we identified groups of metabolites according to the treatments, and we highlighted direct correlations between metabolites within treatments. These results are promising because data issued from field plant studies can be complex to analyze due to environmental artifacts. We optimized experimental conditions (field design, collect, sampling ...) and statistical approaches to reduce this noise. In the objective to improve our knowledge of Eucalyptus biology, integrative studies are in progress (omics, anatomy, wood properties,..), on leaves, cambium and wood, to highlight the Eucalyptus biological responses to mineral fertilization impact on water regulation. These studies will be beneficial to select adapted genotypes to marginal zones with reduced water and/or fertility. Work supported by Cirad, Esalq, Cnpq, Fapesp, Agropolis Fondation, Capes. (Texte intégral)

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