Flow of photosynthesized carbon from rice plants into the paddy soil ecosystem at different stages of rice growth

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• 作者：Akira Watanabe ; Nobuhisa Machida ; Kazushi Takahashi ; Shigeru Kitamura and Makoto Kimura
• 刊名：Plant and Soil
• 出版年：2004
• 出版时间：2004
• 年：2004
• 卷：258
• 期：1
• 页码：151-160
• 全文大小：234 KB

文摘

To elucidate the flow of C assimilated by rice plants into soil C, soil biomass C, and emitted CH₄ at different rice growth stages, 13C pulse-labeling was conducted at the maximum-tiller-number (first experiment), booting (second experiment), and milky stages (third experiment) for potted rice grown outdoors under flooded conditions. The distribution of the assimilated C into each fraction was traced during a 14-day period. The atom-13C % excess of shoots was the highest just after the 6 h feeding of 13CO₂ and decreased until days 14, 7, and 3 in the first, second, and third experiments, respectively. Translocation of the assimilated C into roots was largest in the first experiment, 13 % , while that into ears was more than 50 % in the third experiment. The proportion of the rice-assimilated C recovered in soil organic matter increased with time after labeling and reached 3.4 % , 3.0 % , and 1.7 % on day 14 in the first, second, and third experiments, respectively. Incorporation of the rice-assimilated C was faster into soil microbial biomass than into gross soil organic matter or the 0.5 M K₂SO₄-extractable fraction. Although the percent of labeled soil C that is in the microbial biomass on day 0 was much larger at the maximum-tiller-number stage (42 % ) than at the milky stage (5 % ), its variation among growth stages was small on day 14 (10 to 15 % ). The percent of the rice-assimilated C emitted as CH₄ during the 14-day period at the maximum-tiller-number, booting, and milky stages was 0.003 % , 0.26 % , and 0.30 % , respectively.