CO2 Assimilation Potential of Crop Rubiscos at Varying Temperatures and CO2 Availability

According to the biochemical model of C₃ photosynthesis (Farquhar et al., 1980), A_Rubisco is defined as the minimum of A_c and A_j:

A_Rubisco was obtained for each species at three different temperatures (15°C, 25°C, and 35°C) and two different C_c values (150 and 250 μbar), simulating situations of moderate water-stress and well-watered conditions in C₃ plants, respectively (Flexas et al., 2006). The Rubisco catalytic traits k_catc, Γ*, and K_cair were taken from the species- and temperature-specific data obtained in this study. E was assumed to be invariable at 25 μmol m⁻². Values of J were assumed to be 60, 150, and 212 μmol m⁻² s⁻¹ at 15°C, 25°C, and 35°C, respectively, for all species. At 25°C, J = 150 μmol m⁻² s⁻¹ matches very well with a J/(k_catc × E) ratio of 1.5 (Egea et al., 2011). Values for J at 15°C and 35°C were obtained from the J temperature response described for Nicotiana tabacum by Walker et al. (2013).