Influence of nitrogen and potassium fertilization on leaf lifespan and allocation of above-ground growth in Eucalyptus plantations

Made available in DSpace on 2019-09-12T16:53:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2009 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Universidade de São Paulo (USP) Comité Français d´Evaluation de la Coopération Universitaire avec le Brésil (COFECUB) European Integrated Project 'Ultra Low CO2 Steelmaking' [515960] French Ministry of Foreign Affairs Eucalyptus grandis (W. Hill ex Maiden) leaf traits and tree growth Were Studied over 3 years after the establishment of two adjacent complete randomized block designs in Southern Brazil. In a nitrogen (N) input experiment, a treatment with the application of 120 kg N ha(-1) was compared to a control treatment without N addition, and in I potassium (K) input experiment a control treatment without K addition was compared to a treatment with the application of 116 kg K ha(-1). Young leaves Were tagged 9 months after planting to estimate the effect of N and K fertilizations oil leaf lifespan. Leaf mass, specific leaf area and nutrient concentrations were measured oil a composite sample per plot every 28 days Until the last tagged leaf fell. Successive inventories, destructive sampling of trees and leaf litter fall collection made it possible to assess the effect of N and K fertilization oil the dynamics of biomass accumulation in above-ground tree components. Whilst the effects of N fertilization oil tree growth Only Occurred in the first 24 months after planting, K fertilization increased the above-ground net primary production from 4478 to 8737 g m(-2) over the first 36 months after planting. The average lifespan of tagged leaves was not modified by N addition but it increased from 111 to 149 days with K fertilization. The peak of leaf production Occurred in the second year after planting (about 800 g m(-2) year(-1)) and wits not significantly modified (P < 0.05) by N and K fertilizations. By contrast, K addition significantly increased the maximum leaf standing biomass from 292 to 528 g m(-2) mainly as a consequence of the increase in leaf lifespan. Potassium fertilization increased the stand biomass mainly through the enhancement in leaf area index (LAI) since growth efficiency (defined as the ratio between woody biomass production and LAI) was not significantly modified. A better understanding of the physiological processes governing the leaf lifespan is necessary to improve process-based models Currently used in Eucalyptus plantations. [Laclau, Jean-Paul; Saint-Andre, Laurent; Nouvellon, Yann] CIRAD, Persyst UPR80, TA10 D, F-34398 Montpellier 5, France [Laclau, Jean-Paul; Almeida, Julio C. R.; Goncalves, Jose Leonardo M.; Ventura, Marcelo; Moreira, Rildo M.; Nouvellon, Yann] Univ Sao Paulo, Dept Ciencias Florestais, BR-13418900 Piracicaba, SP, Brazil [Ranger, Jacques] INRA, Biogeochim Ecosyst Forestiers, F-54280 Seichamps, France [Almeida, Julio C. R.] Universidade de Taubaté (Unitau), BR-1202070 Taubate, SP, Brazil