Modeling Light Response of Electron Transport Rate and Its Allocation for Ribulose Biphosphate Carboxylation and...

Accurately describing the light response curve of electron transport rate (J-I curve) and allocation of electron flow for ribulose biphosphate (RuBP) carboxylation (J _C-I curve) and that for oxygenation (J _O-I curve) is fundamental for modeling of light relations of electron flow at the whole-plant and ecosystem scales. The non-rectangular hyperbolic model (hereafter, NH model) has been widely used to characterize light response of net photosynthesis rate (A _n; A _n-I curve) and J-I curve. However, NH model has been reported to overestimate the maximum A _n (A _nmax) and the maximum J (J _max), largely due to its asymptotic function. Meanwhile, few efforts have been delivered for describing J _C-I and J _O-I curves. The long-standing challenge on describing A _n-I and J-I curves have been resolved by a recently developed A _n-I and J-I models (hereafter, Ye model), which adopt a nonasymptotic function. To test whether Ye model can resolve the challenge of NH model in reproducing J-I, J _C-I and J _O-I curves over light-limited, light-saturated, and photoinhibitory I levels, we compared the performances of Ye model and NH model against measurements on two C₃ crops (Triticum aestivum L. and Glycine max L.) grown in field. The results showed that NH model significantly overestimated the A _nmax and J _max for both species, which can be accurately obtained by Ye model. Furthermore, NH model significantly overestimated the maximum electron flow for carboxylation (J _C-max) but not the maximum electron flow for oxygenation (J _O-max) for both species, disclosing the reason underlying the long-standing problem of NH model-overestimation of J _max and A _nmax.