Journal Article

Seasonal Changes in Canopy Photosynthesis and Respiration, and Partitioning of Photosynthate, in Rice (<i>Oryza sativa</i> L.) Grown Under Free-Air CO<sub>2</sub> Enrichment

Haruto Sasaki, Takahiro Hara, Satoshi Ito, Shu Miura, Md. Mozammel Hoque, Mark Lieffering, Han-Yong Kim, Masumi Okada and Kazuhiko Kobayashi

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 46, issue 10, pages 1704-1712
Published in print October 2005 | ISSN: 0032-0781
Published online October 2005 | e-ISSN: 1471-9053 | DOI: https://dx.doi.org/10.1093/pcp/pci186
Seasonal Changes in Canopy Photosynthesis and Respiration, and Partitioning of Photosynthate, in Rice (Oryza sativa L.) Grown Under Free-Air CO2 Enrichment

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An increase in atmospheric CO2 concentration ( [CO2]) is generally expected to enhance photosynthesis and biomass. Rice plants (Oryza sativa L.) were grown in ambient CO2 (AMB) or free-air CO2-enrichment (FACE), in which the target [CO2] was 200 µmol mol–1 above AMB. 13CO2 was fed to the plants at different stages so we could examine the partitioning of photosynthates. Furthermore, canopy photosynthesis and respiration were measured at those stages. The ratio of 13C content in the whole plant to the amount of fixed 13C under FACE was similar to that under AMB at the vegetative stage. However, the ratio under FACE was greater than the ratio under AMB at the grain-filling stage. At the vegetative stage, plants grown under FACE had a larger biomass than those grown under AMB owing to enhancement of canopy photosynthesis by the increased [CO2]. On the other hand, at the grain-filling stage, CO2 enrichment promoted the partitioning of photosynthate to ears, and plants grown under FACE had a greater weight of ears. However, enhancement of ear weight by CO2 enrichment was not as great as that of biomass at the vegetative stage. Plants grown under FACE did not necessarily show higher canopy photosynthetic rates at the grain-filling stage. Therefore, we concluded that the ear weight did not increase as much as biomass at the vegetative stage owing to a loss of the advantage in CO2 gain during the grain-filling period.

Keywords: 13C; Carbohydrate; FACE; Grain filling; Grain yield; Translocation; AMB, ambient CO2; Cdec, the decreasing rate of CO2 concentration; Cinc, the increasing rate of CO2 concentration; [CO2], CO2 concentration; DAT, day after transplanting; FACE, free-air CO2 enrichment; LAI, green leaf area index; PFD, photon flux density

Journal Article.  6692 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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