Under elevated CO2, carboxylation process also
increases producing glycolate and inhibiting photorespiration.
These effects are important and they increase the
efficiency of net carbon gain by decreasing photorespiratory
CO2 loss and diverting ATP and NADPH away from
photorespiratory metabolism to photosynthetic assimilation
(Elizabeth and Alistair 2007). The extra assimilates produced
are then allocated to biomass and leaf area resulted
in increases in total dry weight, shoot to root ratio, leaf
thickness, stem diameter, relative growth rate (RGR) and
net assimilation rate (NAR). However, growth enhancement
under elevated CO2 is dependent on the plant species,
duration of CO2 exposure and the sink strength of the plant
(Kowlozsky et al. 1991). The seedlings that are enhanced
with elevated CO2 also usually have higher water use
efficiency (WUE) as decrease in stomatal aperture and
stomatal density reduce stomatal conductance (gs) and
subsequently reducing transpiration rate (Ghannoum et al.
2000).