2.3.3 Physiological characteristics
The physiological characteristics of fully expanded leaves, including net photosynthetic rate (Pn, μmol CO2m-2 s-1), transpiration rate (Tr, mmol H2O m-2 s-1) and stomatal conductance (Gs, mmol H2O m-2 s-1), were measured using a Li-6800 portable photosynthesis-measurement system under saturating light conditions of 1300 μmol photons m2s−1 (Li-Cor Biosciences, Lincoln, NE, USA). During measurements, the leaf temperature was controlled at 25℃, while the ambient CO2 concentration was set as 400 μmol CO2 mol−1.