Rice yield enhancement by elevated CO2 is reduced in cool weather

Authors

  • HIROYUKI SHIMONO,

    1. Climate Change Research Team, National Agricultural Research Center for Tohoku Region, Shimokuriyagawa, Iwate 020-0198, Japan,
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  • MASUMI OKADA,

    1. Climate Change Research Team, National Agricultural Research Center for Tohoku Region, Shimokuriyagawa, Iwate 020-0198, Japan,
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  • YASUHIRO YAMAKAWA,

    1. Climate Change Research Team, National Agricultural Research Center for Tohoku Region, Shimokuriyagawa, Iwate 020-0198, Japan,
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  • HIROFUMI NAKAMURA,

    1. Climate Change Research Team, National Agricultural Research Center for Tohoku Region, Shimokuriyagawa, Iwate 020-0198, Japan,
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  • KAZUHIKO KOBAYASHI,

    1. Department of Global Agricultural Science, Graduate School of Agricultural and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan,
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  • TOSHIHIRO HASEGAWA

    1. Division of Agro-Meteorology, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan
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Present address: Hiroyuki Shimono, Faculty of Agriculture, Iwate University, 3-18-8, Ueda, Morioka, Iwate 020-8550, Japan, tel. +81 19 621 6146, fax +81 19 621 6117, e-mail: shimn@iwate-u.ac.jp

Abstract

The projected increase of atmospheric CO2 concentration ([CO2]) is expected to increase rice yield, but little is known of the effects of [CO2] at low temperature, which is the major constraint to growing rice in cool climates. We grew rice under two levels of [CO2] (ambient and elevated by 200 μmol mol−1) and two nitrogen (N) fertilization regimes in northern Japan in 2003 (cool weather) and 2004 (warm weather) in the field in a free-air CO2 enrichment (FACE) system. Elevated [CO2] significantly increased grain yield in both years in both N regimes, but the magnitude of the increase differed between years: 6% in 2003 vs. 17% in 2004, with a significant interaction between [CO2] and year. This difference resulted from responses of spikelet number and ripening percentage to elevated [CO2]. Enhancement of dry matter production and N uptake at heading by elevated [CO2] was smaller in 2003 than in 2004, although at maturity there was no difference between years. No significant interaction between N regime and [CO2] was detected in yield and yield components. The results suggest that yield gain due to elevated [CO2] can be reduced by low temperature.

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