PHOTOSYNTHETICA

Photosynthetica 2021, 59(1):185-191 | DOI: 10.32615/ps.2021.009

Quantifying light response of photosynthesis: addressing the long-standing limitations of non-rectangular hyperbolic model

Z.P. YE¹, S.H. DUAN², X.M. CHEN³, H.L. DUAN⁴, C.P. GAO⁵, H.J. KANG^{6, 7}, T. AN¹, S.X. ZHOU⁸

¹ Maths & Physics College, Jinggangshan University, 343009 Ji'an, China

² School of Life Sciences, Jinggangshan University, 343009 Ji'an, China

³ Soil Fertilizer and Environmental Resources Institute, Jiangxi Academy of Agricultural Sciences, 330200 Nanchang, China

⁴ Jiangxi Provincial Key Laboratory for Restoration of Degraded Ecosystems & Watershed Ecohydrology, Nanchang Institute of Technology, 330099 Nanchang, China

⁵ College of Grassland Resources and Environment, Key Laboratory of Grassland Resources of the Ministry of Education, Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization of the Ministry of Agriculture and Rural Affairs, Inner Mongolia Autonomous Region Key Laboratory of Grassland Management and Utilization, Inner Mongolia Agricultural University, 010011 Hohhot, China

⁶ Wenzhou Academy of Agricultural Sciences, 325006 Wenzhou, China

⁷ Southern Zhejiang Key Laboratory of Crop Breeding, 325001 Wenzhou, China

⁸ The New Zealand Institute for Plant and Food Research Limited, Hawke's Bay 4130, New Zealand

Light intensity (I) fluctuates rapidly and is the most important environmental factor affecting photosynthesis. Accurate characterization of light-response curve of leaf-scale photosynthesis (P_N-I curve) is fundamental for understanding P_N-I relations at the whole-plant and ecosystem scales. A robust P_N-I model should be accurate in reproducing P_N-I curves over light-limited, light-saturated, and photoinhibitory I levels, and ideally returning key quantitative traits defining the curves, including initial slope of increase (α), dark respiration rate (R_D), the maximum net photosynthetic rate (P_Nmax), and the corresponding saturation intensity (I_sat). We need to improve a model reproduction of (1) P_N-I responses over low I levels and (2) the widely reported decline of P_N at photoinhibitory I levels. Our observation-modelling comparison, shown by the widely used non-rectangular hyperbolic model, led to (1) underestimation of R_D, (2) overestimation of P_Nmax, and (3) failure in reproducing the photoinhibitory response when I surpassed the cultivar-specific I_sat. In contrast, our model addressed the above limitations extremely well. The results highlighted the accuracy and robustness of our model, especially in (1) returning key traits defining the curve and (2) reproducing the curve over both low [i.e., 0-50 μmol(photon) m^-2 s^-1] and photoinhibitory I levels (i.e., beyond I_sat).

Additional key words: Received 26 May 2020

Received: May 26, 2020; Revised: November 6, 2020; Accepted: February 1, 2021; Prepublished online: February 26, 2021; Published: March 18, 2021  Show citation