Increased light-use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system

Fabien Charbonnier*, Olivier Roupsard, Guerric le Maire, Joannès Guillemot, Fernando Casanoves, André Lacointe, Philippe Vaast, Clémentine Allinne, Louise Audebert, Aurélie Cambou, Anne Clément-Vidal, Elsa Defrenet, Remko A. Duursma, Laura Jarri, Christophe Jourdan, Emmanuelle Khac, Patricia Leandro, Belinda E. Medlyn, Laurent Saint-André, Philippe ThalerKarel Van Den Meersche, Alejandra Barquero Aguilar, Peter Lehner, Erwin Dreyer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees.

Original languageEnglish
Pages (from-to)1592-1608
Number of pages17
JournalPlant Cell and Environment
Volume40
Issue number8
DOIs
Publication statusPublished - Aug 2017
Externally publishedYes

Keywords

  • carbon allocation
  • Coffea arabica
  • light absorption model
  • MAESPA
  • net assimilation rate (NAR)

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