Plant productivity is directly affected by two important aspects
of global climate change caused by abundance of green house gases
in the atmosphere. One is rising atmospheric carbon dioxide (CO2)
while another is tropospheric ozone (O3) (Ainsworth et al., 2008).
Fast consumption of the fossil fuels and land use changes are
mainly responsible for significant increase in the atmospheric CO2
concentration which is projected to reach between 585 and
700 ppm by the end of this century under different greenhouse
emission scenarios (IPCC, 2007)