Extending the 'one-point method' for estimations of leaf photosynthetic capacity to a broader temperature range

Abstract

The 'one-point method' (OPM) is a quick approach to estimate the maximum apparent carboxylation rate of Rubisco (Vcmax) based on a single measurement of leaf carbon assimilation rate taken under saturating light and ambient CO2, lately equal to 400ppm (De Kauwe et al., 2016). However, the OPM overestimates Vcmax at high temperatures (Burnett et al., 2019). This overestimation results from the reliance of the method on a linear relationship between Vcmax and leaf respiration rates under light (Rday), as a fixed Rday:Vcmax ratio equal to 1.5%, while these parameters have different temperature dependencies. Here, we highlight the importance of the adoption of a temperature-dependent scaling factor for the Rday:Vcmax ratio as a way to prevent the overestimation of the photosynthetic capacity at temperatures 35 °C.