TY - JOUR
T1 - Increased light-use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system
AU - Charbonnier, Fabien
AU - Roupsard, Olivier
AU - le Maire, Guerric
AU - Guillemot, Joannès
AU - Casanoves, Fernando
AU - Lacointe, André
AU - Vaast, Philippe
AU - Allinne, Clémentine
AU - Audebert, Louise
AU - Cambou, Aurélie
AU - Clément-Vidal, Anne
AU - Defrenet, Elsa
AU - Duursma, Remko A.
AU - Jarri, Laura
AU - Jourdan, Christophe
AU - Khac, Emmanuelle
AU - Leandro, Patricia
AU - Medlyn, Belinda E.
AU - Saint-André, Laurent
AU - Thaler, Philippe
AU - Van Den Meersche, Karel
AU - Barquero Aguilar, Alejandra
AU - Lehner, Peter
AU - Dreyer, Erwin
PY - 2017/8
Y1 - 2017/8
N2 - 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.
AB - 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.
KW - carbon allocation
KW - Coffea arabica
KW - light absorption model
KW - MAESPA
KW - net assimilation rate (NAR)
UR - http://www.scopus.com/inward/record.url?scp=85021262986&partnerID=8YFLogxK
U2 - 10.1111/pce.12964
DO - 10.1111/pce.12964
M3 - Article
C2 - 28382683
AN - SCOPUS:85021262986
VL - 40
SP - 1592
EP - 1608
JO - Plant, Cell & Environment
JF - Plant, Cell & Environment
SN - 0140-7791
IS - 8
ER -