Determination of photosynthetic parameters Vcmax and Jmax for a C3 plant (spring hulless barley) at two altitudes on the Tibetan Plateau

► Photosynthetic parameters Vcmax and Jmax were determined on the Tibetan Plateau. ► Parameters were higher for plants at higher altitude than those at lower altitude. ► CO2 and temperature dependences of Pn were predicted if adopting Jmax and Vcmax. ► An inevitable decrease of Pn would occur if CO2 and temperature increasing continues.