Quantifying Light Response of Leaf-Scale Water-Use Efficiency and Its Interrelationships With Photosynthesis and Stomatal Conductance in C3 and C4 Species

Frontiers in Plant Science

Yu Ling¹  Xian-Mao Chen²  Hua-Jing Kang⁴  Shi-Hua Duan⁵  Qiang Yu⁶  Guo-Min Huang⁷  Yu-Guo Liu⁷  Zi-Piao Ye⁸  Shuang-Xi Zhou⁹  Hong-Lang Duan^1,10 

[1] Physics College, Jinggangshan University, Ji’an, China;Technology, Wenzhou, China;College of Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China;College of Resources and Environment, University of Chinese Academy of Science, Beijing, China;;Department of Landscape Architecture, Wenzhou Vocational College of Science &F University, Yangling, China;Jiangxi Provincial Key Laboratory for Restoration of Degraded Ecosystems and Watershed Ecohydrology, Nanchang Institute of Technology, Nanchang, China;;Maths &School of Life Sciences, Jinggangshan University, Ji’an, China;School of Life Sciences, University of Technology Sydney, Ultimo, NSW, Australia;;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&

关键词: irradiance;    leaf gas exchange;    light response curve;    maximum water use efficiency;    model;    plant functional type (PFT);   

DOI  :  10.3389/fpls.2020.00374

来源: DOAJ

【 摘 要 】

Light intensity (I) is the most dynamic and significant environmental variable affecting photosynthesis (An), stomatal conductance (gs), transpiration (Tr), and water-use efficiency (WUE). Currently, studies characterizing leaf-scale WUE–I responses are rare and key questions have not been answered. In particular, (1) What shape does the response function take? (2) Are there maximum intrinsic (WUEi; WUEi–max) and instantaneous WUE (WUEinst; WUEinst–max) at the corresponding saturation irradiances (Ii–sat and Iinst–sat)? This study developed WUEi–I and WUEinst–I models sharing the same non-asymptotic function with previously published An–I and gs–I models. Observation-modeling intercomparison was conducted for field-grown plants of soybean (C3) and grain amaranth (C4) to assess the robustness of our models versus the non-rectangular hyperbola models (NH models). Both types of models can reproduce WUE–I curves well over light-limited range. However, at light-saturated range, NH models overestimated WUEi–max and WUEinst–max and cannot return Ii–sat and Iinst–sat due to its asymptotic function. Moreover, NH models cannot describe the down-regulation of WUE induced by high light, on which our models described well. The results showed that WUEi and WUEinst increased rapidly within low range of I, driven by uncoupled photosynthesis and stomatal responsiveness. Initial response rapidity of WUEi was higher than WUEinst because the greatest increase of An and Tr occurred at low gs. C4 species showed higher WUEi–max and WUEinst–max than C3 species—at similar Ii–sat and Iinst–sat. Our intercomparison highlighted larger discrepancy between WUEi–I and WUEinst–I responses in C3 than C4 species, quantitatively characterizing an important advantage of C4 photosynthetic pathway—higher An gain but lower Tr cost per unit of gs change. Our models can accurately return the wealth of key quantities defining species-specific WUE–I responses—besides An–I and gs–I responses. The key advantage is its robustness in characterizing these entangled responses over a wide I range from light-limited to light-inhibitory light intensities, through adopting the same analytical framework and the explicit and consistent definitions on these responses. Our models are of significance for physiologists and modelers—and also for breeders screening for genotypes concurrently achieving maximized photosynthesis and optimized WUE.

【 授权许可】

Unknown