title: Photosynthetic and anatomical responses of Eucalyptus grandis leaves to potassium and sodium supply in a field experiment.
abstract: 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.
authors.affiliation: Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, CEP 13400-970, Piracicaba, SP, Brazil.
authors.forename: Patricia
authors.initials: P
authors.lastname: Battie-Laclau
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Laclau
authors.forename: Constance
authors.initials: C
authors.lastname: Beri
authors.forename: Lauriane
authors.initials: L
authors.lastname: Mietton
authors.forename: Marta R Almeida
authors.initials: MR
authors.lastname: Muniz
authors.forename: Bruna Cersózimo
authors.initials: BC
authors.lastname: Arenque
authors.forename: Marisa
authors.initials: M
authors.lastname: DE Cassia Piccolo
authors.forename: Lionel
authors.initials: L
authors.lastname: Jordan-Meille
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bouillet
authors.forename: Yann
authors.initials: Y
authors.lastname: Nouvellon
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D005052:Eucalyptus / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D058503:Mesophyll Cells / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D011188:Potassium / Q000032:analysis / Q000494:pharmacology*; D012964:Sodium / Q000032:analysis / Q000494:pharmacology*; D014197:Trees
chemical_list: D002734:Chlorophyll; D002245:Carbon Dioxide; D012964:Sodium; D009584:Nitrogen; D011188:Potassium
keywords: A-Ci curves; K; Na; eucalypt; leaf anatomy; mesophyll conductance; nutrient; photosynthesis; stomatal conductance