Estimation of mesophyll conductance (gm) and CO2 concentration in the chloroplast (Cc)
Estimation of g m was made by the method of Harley et al. (1992), using the following equation:
J = 4 (A +R L) (C i-A n/g m) + 2 Γ */ (C i-A /g m)-Γ *,
where, J is photosynthetic electron transport, A - net CO2 assimilation, C i- intercellular [CO2], R L- the rate of mitochondrial respiration in the light, Γ *- the CO2 compensation point in the absence of R L (Evans & Loreto, 2000), and the factor 4 is for the minimum electron requirement for carboxylation. Values for J were derived from Chl fluorescence. The CO2 concentration in the chloroplast (C c) was measured by usingC c= C i-A n/g m (Pons et al., 2009).