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

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

Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871; † Corresponding author, E-mail: kanghuixing@pku.edu.cn

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