Song Qingfeng, Van Rie Jeroen, Den Boer Bart, Galle Alexander, Zhao Honglong, Chang Tiangen, He Zhonghu, Zhu Xin-Guang
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
BASF Belgium Coordination Center - Innovation Center Gent, Ghent, Belgium.
Front Plant Sci. 2022 Feb 25;13:817654. doi: 10.3389/fpls.2022.817654. eCollection 2022.
Improving canopy photosynthetic light use efficiency and energy conversion efficiency (ε ) is a major option to increase crop yield potential. However, so far, the diurnal and seasonal variations of canopy light use efficiency (LUE) and ε are largely unknown due to the lack of an efficient method to estimate ε in a high temporal resolution. Here we quantified the dynamic changes of crop canopy LUE and ε during a day and a growing season with the canopy gas exchange method. A response curve of whole-plant carbon dioxide (CO) flux to incident photosynthetically active radiation (PAR) was further used to calculate ε and LUE at a high temporal resolution. Results show that the LUE of two wheat cultivars with different canopy architectures at five stages varies between 0.01 to about 0.05 mol CO mol photon, with the LUE being higher under medium PAR. Throughout the growing season, the ε varies from 0.5 to 3.7% (11-80% of the maximal ε for C plants) with incident PAR identified as a major factor controlling variation of ε . The estimated average ε from tillering to grain filling stages was about 2.17%, i.e., 47.2% of the theoretical maximal. The estimated season-averaged radiation use efficiency (RUE) was 1.5-1.7 g MJ, which was similar to the estimated RUE based on biomass harvesting. The large variations of LUE and ε imply a great opportunity to improve canopy photosynthesis for greater wheat biomass and yield potential.
提高冠层光合光利用效率和能量转换效率（ε）是提高作物产量潜力的主要途径。然而，由于缺乏一种能在高时间分辨率下估算ε的有效方法，到目前为止，冠层光利用效率（LUE）和ε的日变化和季节变化在很大程度上尚不清楚。在此，我们利用冠层气体交换法对作物冠层LUE和ε在一天和一个生长季中的动态变化进行了量化。进一步利用全株二氧化碳（CO）通量对光合有效辐射（PAR）的响应曲线，在高时间分辨率下计算ε和LUE。结果表明，两个具有不同冠层结构的小麦品种在五个生育阶段的LUE在0.01至约0.05 μmol CO₂ μmol⁻¹光子之间变化，中等PAR下LUE更高。在整个生长季，ε在0.5%至3.7%之间变化（C₃植物最大ε的11% - 80%），入射PAR被确定为控制ε变化的主要因素。从分蘖期到灌浆期估算的平均ε约为2.17%，即理论最大值的47.2%。估算的季节平均辐射利用效率（RUE）为1.5 - 1.7 g MJ⁻¹，这与基于生物量收获估算的RUE相似。LUE和ε的较大变化意味着通过改善冠层光合作用提高小麦生物量和产量潜力的巨大机会。
