期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 67, 期 1, 页码 341-352出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/erv463
关键词
Carbohydrates; Coffea arabica L.; FACE; nitrogen; photosynthetic limitations; photosynthetic acclimation; starch
资金
- Embrapa [01.07.06.002.00, 02.12.01.018.00]
- Foundation for Research Assistance of Minas Gerais State, Brazil (FAPEMIG) [APQ 04784/10]
- National Council for Scientific and Technological Development, Brazil (CNPq) [562157/2010-7, 304189/2013-8]
- Brazilian Federal Agency for the Support and Evaluation of Graduate Education (CAPES)
- FAPEMIG
- CNPq
Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuai and Obata) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest.
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