Strong spatial variability of light use efficiency in a coffee AFS highlighted by 3D light and gas exchange model

Charbonnier Fabien, Roupsard Olivier, Casanoves Fernando, Audebert Louise, Defresnet Elsa, Cambou Aurélie, Allinne Clémentine, Rapidel Bruno, Avelino Jacques, Van den Meersche Karel, Harmand Jean-Michel, Jourdan Christophe, Vaast Philippe, Barquero Alejandra, Leandro Patricia, Dreyer Erwin. 2014. Strong spatial variability of light use efficiency in a coffee AFS highlighted by 3D light and gas exchange model. In : Abstracts of the 3rd World Congress of Agroforestry 'Trees for life: accelerating the impact of agroforestry' : abstracts. Wachira Mary Anne (ed.), Rabar Betty (ed.), Magaju Christine (ed.), Borah Gulshan (ed.). Nairobi : WCA [Nairobi], 72. ISBN 92-9059-372-5 World Congress on Agroforestry, Delhi, Inde, 10 Février 2014/14 Février 2014.

Résumé : Above-ground net primary productivity (NPP) of individual arabica coffee plants (60 coffee resprouts, of various ages (0 to 5 years, after pruning), located below or far from the shade trees) was assessed during two years in the field from repeated biomass estimations (via branch scale allometry) and litter harvest (30 litter traps) (Coffee Flux Observatory, http://www5.montpellier.inra.fr/ecosols/Recherche/Les-projets/CoffeeFlux). Suprisingly, NPP was not influenced by the distance to the shade trees. MAESTRA, a 3D light interception model was applied to map shade tree transmittance and to calculate yearly light budgets (absorbed photosynthetically active radiation, aPAR) of the coffee plants (Charbonnier et al., 2013). Light use efficiency (LUE) of coffee plants was calculated dividing their annual NPP by plant aPAR. MAESTRA showed that aPAR decreased severely for coffee plants located under shade tree crowns (down to 70%). However, we obtained a 2-fold increase in LUE for coffee plants located under shade trees, and a spatial gradient of LUE according to the distance to the shade tree. The analysis revealed that the increase in LUE totally compensated the expected reduction of NPP due to the reduction in aPAR. We will discuss the possible causes of such an increase in LUE and the genericity of this finding. We will also emphasize on the role played by the 3D light interception model in the demonstration of this crucial property for AFS.

Classification Agris : F08 - Systèmes et modes de culture
F60 - Physiologie et biochimie végétale
K10 - Production forestière

Auteurs et affiliations

• Charbonnier Fabien
• Roupsard Olivier, CIRAD-PERSYST-UMR Eco&Sols (CRI)
• Casanoves Fernando, CATIE (CRI)
• Audebert Louise, Université de Lorraine (FRA)
• Defresnet Elsa, Agrocampus Ouest (FRA)
• Cambou Aurélie, ENSAIA (FRA)
• Allinne Clémentine, CIRAD-PERSYST-UMR SYSTEM (CRI)
• Rapidel Bruno, CIRAD-PERSYST-UMR SYSTEM (CRI) ORCID: 0000-0003-0288-5650
• Avelino Jacques, CIRAD-BIOS-UPR Bioagresseurs (CRI) ORCID: 0000-0003-1983-9431
• Van den Meersche Karel, CIRAD-PERSYST-UMR Eco&Sols (CRI) ORCID: 0000-0002-0866-7657
• Harmand Jean-Michel, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0002-8065-106X
• Jourdan Christophe, CIRAD-PERSYST-UMR Eco&Sols (FRA) ORCID: 0000-0001-9857-3269
• Vaast Philippe, CIRAD-PERSYST-UMR Eco&Sols (KEN)
• Barquero Alejandra, Cafetalera Aquiares (CRI)
• Leandro Patricia, CATIE (CRI)
• Dreyer Erwin, INRA (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/573067/)

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