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Photosynthetic and anatomical responses of Eucalyptus grandis leaves to potassium and sodium supply in a field experiment

Battie Laclau P., Laclau J.P., Beri C., Mietton L., Almeida Muniz M.R., Cersózimo Arenque B., De Cassia Piccolo M., Jordan-Meille L., Bouillet J.P., Nouvellon Y.. 2014. Plant, Cell and Environment, 37 (1) : p. 70-81.

Although vast areas in tropical regions have weathered soils with low potassium (K) levels, little is known about the effects of K supply on the photosynthetic physiology of trees. This study assessed the effects of K and sodium (Na) supply on the diffusional and biochemical limitations to photosynthesis in Eucalyptus grandis leaves. A field experiment comparing treatments receiving K (+K) or Na (+Na) with a control treatment (C) was set up in a K-deficient soil. The net CO2 assimilation rates were twice as high in +K and 1.6 times higher in +Na than in the C as a result of lower stomatal and mesophyll resistance to CO2 diffusion and higher photosynthetic capacity. The starch content was higher and soluble sugar was lower in +K than in C and +Na, suggesting that K starvation disturbed carbon storage and transport. The specific leaf area, leaf thickness, parenchyma thickness, stomatal size and intercellular air spaces increased in +K and +Na compared to C. Nitrogen and chlorophyll concentrations were also higher in +K and +Na than in C. These results suggest a strong relationship between the K and Na supply to E.?grandis trees and the functional and structural limitations to CO2 assimilation rates. (Résumé d'auteur)

Mots-clés : séquestration du carbone; morphologie végétale; feuille; analyse de tissu foliaire; sodium; potassium; fertilisation; photosynthèse; plantation forestière; eucalyptus grandis; brésil; parcelle expérimentale; indice foliaire

Thématique : Production forestière; Fertilisation; Physiologie végétale : croissance et développement; Anatomie et morphologie des plantes

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