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).