DOI: 10.32328/turkjforsci.1943941 ISSN: 2618-6616

Photorespiratory flux in C3 plants: A meta-analysis of FvCB model fits to published A-Cc and A-PAR data across crop and forest species

Emre Yazar
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Photorespiration constrains net carbon gain in C3 plants by competing with carboxylation at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Quantifying this flux requires kinetic models that accurately describe the CO2 and light dependence of assimilation across diverse species and temperatures. Here I perform a meta-analysis of published A-Cc and A-PAR curves from eleven species-temperature combinations spanning six crop species - Nicotiana tabacum, Glycine max, Triticum aestivum, Arabidopsis thaliana, Helianthus annuus and Gossypium hirsutum ̶ and three temperate forest tree species ̶ European beech (Fagus sylvatica L.), pedunculate oak (Quercus robur L.), and silver birch (Betula pendula Roth) ̶ over a temperature range of 22-35°C. I fit the Farquhar-von Caemmerer-Berry (FvCB) model to each dataset using nonlinear least-squares optimization with Bernacchi temperature-response functions and extract maximum carboxylation rates (Vcmax), maximum electron transport rates (Jmax), day respiration (Rd), and CO2 compensation points (Γ*). Fitted Vcmax ranged from 137.5 to 244.4 µmol m⁻² s⁻¹ across all species, with forest species spanning the upper half of the range (178.6-244.4 µmol m⁻² s⁻¹) and silver birch showing the highest Vcmax of any species in the dataset, consistent with published reports for temperate broadleaf trees. Model fits were excellent across all A-Cc curves (R² = 0.957-0.994, RMSE = 0.65-2.44 µmol m⁻² s⁻¹) and satisfactory for A-PAR curves (R² = 0.80-0.97). Photorespiratory CO2 release (Rp) at pre-industrial CO2 (Cc ≈ 280 µbar) accounted for 18-26% of gross assimilation, and 14-21% at current ambient CO2 (Cc ≈ 420 µbar), with no systematic difference between crop and forest species at the same temperature, confirming that the Γ*/CcTo our knowledge, this is the first meta-analysis to apply a single, consistently parameterized FvCB framework to both crop and temperate forest tree species and to compare their photorespiratory flux on a common basis. Ratio rather than species identity is the primary determinant of photorespiratory fraction. These results validate the FvCB framework across a taxonomically diverse C3 species set and provide a consolidated parameterization for canopy-scale and Earth system modelling.

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