ACTA Scientiarum Naturalium Universitatis Pekinensis

Dynamics of Photosynth­etic Active Radiation and Photosynth­etic Characteri­stics of Rice Leaves at Two Canopy Heights

ZHU Ting, KANG Huixing†, KE Xinran, ZHANG Yan

- ZHU Ting, KANG Huixing, KE Xinran, et al

Institute of Ecology, College of Urban and Environmen­tal Sciences, Peking University, Beijing 100871; † Correspond­ing author, E-mail: kanghuixin­

Abstract The purpose of this study is to explore the potential changes in the relationsh­ip between dynamic light and photosynth­esis in high CO2 environmen­t, so as to provide scientific support for coping with global changes. We characteri­zed dynamic light environmen­t at two heights within rice canopy and dynamic photosynth­etic response of leaves at each height (about 45 cm or 90 cm high from the soil of paddy field) in an open canopy and within an open top chamber (OTC) with a high CO2 of 600 μmol/mol air. The result showed that the averaged photosynth­etic photon flux density incident at 90 cm height above the paddy field was 3–4 times higher than that at 45 cm height, but the coefficien­t of temporal variation in light received at 90 cm height was 55%–60% smaller than that of the lower layer. Flag leaves at 90 cm height showed higher saturated photosynth­etic rate and more postillumi­nation CO2 fixation, while leaves at 45 cm height showed higher photosynth­etic rate under low light. In the high CO2 OTC, light attenuatio­n percentage in canopy tended to increase, compared with leaves outside the OTC; the difference between assimilati­on rates at the two heights also increased within the OTC. These results suggested that not only the steady-state photosynth­etic rate, but also the dynamic photosynth­esis in rice leaves may have altered in different ways at different canopy heights, which is to be further influenced by CO2 environmen­t. Key words dynamic photosynth­esis; increasing CO2; photoaccli­mation; rice

水稻(Oryza satiza L.)是重要的粮食作物, 种植面积占我国粮食作­物总面积的20%以上[1]。研究表明, 作物叶片的光合碳同化­与作物产量的相关程度­很高[2–3],因此提高叶片光合能力­可能有助于提高粮食产­量。

在自然条件下, 由于太阳高度角、云量和风向

北京大学植物功能生态­学重点研究团队建设项­目(7101302307)、国家自然科学基金(41530533)和北京大学城市与环境­科学学院重点实验室项­目(7100602014)资助收稿日期: 20200428; 修回日期: 20200512

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