Stomatal conductance (gs) and water use
efficiency (WUE)
The CO2 assimilation rate, measured at 400 µmol photons
m-2 s-1, was 14% and 19% higher in
CAx3 and CAx5 than in the VC (Fig. 6c ). It is important to note
that increases in photosynthetic rates were associated with decreases in
stomatal conductance and transpiration rates in the transgenic lines.
Stomatal conductance decreased by 7% - 13% in the transgenics, as
compared to VC plants (Fig. 6d ). Consequently, the
transpiration rate decreased by 7% -10% in FbβCA overexpressor
plants (Fig. 6e ). Therefore, the water use efficiency, which is
the ratio of the CO2 assimilation rate to the
transpiration rate (μmol CO2 m-2s-1/mmol H2O m-2s-1) was higher by 22% and 26% in CAx3 and CAx5,
respectively, than that in VC (Fig. 6f ).