Zhu Yong-li, Wu Jin-shui, Tong Cheng-li, Wang Ke-lin, Wang Qin-xue
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Huan Jing Ke Xue. 2008 Apr;29(4):1040-4.
CO2 fluxes in rice paddy ecosystem in subtropical hilly region were measured continuously using eddy covariance technique. The objectives were to investigate the responses of CO2 fluxes to light intensity and temperature in the paddy ecosystem. Results showed a rectangular hyperbolic light-response function could be used to describe the relationship of CO2 flux and photosynthetic photon flux density (PPFD). The absolute values of CO2 fluxes increased with the increment of PPFD. When PPFD was higher than 1000 micromol/(m2 x s), the maximum was observed. CO2 fluxes responded differently to light between early and late rice. Values of quantum yield of late rice (0.0465-0.0999 micromol/micromol) were general higher than that of early rice (0.0176-0.0541 micromol/micromol). Moreover, the quantum yield and the maximum rate of photosynthesis assimilation in the blooming stage were higher than that in tillering and ripening stages. In nighttime, respiration from soil and plants (ecosystem respiration, Reco) changed exponentially with the increase of soil temperature at the depth of 5 cm (T5), 10 cm (T10), and 20 cm (T20), respectively. Whereas, T5 was more feasible than others to be considered as the temperature parameter for Reco calculation. During early rice growing season, Reco was more sensitive to temperature change than that during late rice growing season.
利用涡度相关技术连续测定了亚热带丘陵地区稻田生态系统中的二氧化碳通量。目的是研究稻田生态系统中二氧化碳通量对光照强度和温度的响应。结果表明，可用矩形双曲线光响应函数来描述二氧化碳通量与光合有效辐射（PPFD）之间的关系。二氧化碳通量的绝对值随PPFD的增加而增大。当PPFD高于1000微摩尔/（平方米·秒）时，观测到最大值。早稻和晚稻对光的二氧化碳通量响应不同。晚稻的量子产量（0.0465 - 0.0999微摩尔/微摩尔）一般高于早稻（0.0176 - 0.0541微摩尔/微摩尔）。此外，开花期的量子产量和最大光合同化率高于分蘖期和成熟期。在夜间，土壤和植物的呼吸作用（生态系统呼吸，Reco）分别随5厘米深度（T5）、10厘米深度（T10）和20厘米深度（T20）处土壤温度的升高呈指数变化。然而，将T5作为Reco计算的温度参数比其他参数更合适。在早稻生长季，Reco对温度变化比晚稻生长季更敏感。
