Physiological response of C3, C4 and CAM plants in changeable climate

Climate Change is a serious global problem due to increase the global average surface temperature. The global average surface temperature increased by 1.5-4.5°C over the next 100 years. It is primarily caused by the building up of Green House Gases (GHG) in the atmosphere. Global Warming is a specific example of the broader term “Climate Change”. C3 photosynthesis is an excellent compromise of photosynthetic efficiency due to photorespiration. C4 photosynthesis is suited to maintained photosynthesis and productivity for plants that have evolved in drier and warmer environments. CAM plants acclimated days and night photosynthetic process differentially to temperature. Moreover, within C3 species, evergreen woody plants and perennial herbaceous plants showed greater temperature homeostasis of photosynthesis (i.e., the photosynthetic rate at high growth temperature divided by that at low-growth temperature was close to 1.0 μmol CO2 m-2 s-1) than deciduous woody plants and annual herbaceous plants. It is considered that these differences in the inherent stability of temperature acclimation of photosynthesis would be reflected by differences in the limiting steps of photosynthetic rate. The largest negative yield impacts are projected for wheat crop (1oC rise in temperature reduces 4-5 million tonnes of wheat yield). Overall, millet and sorghum yields are projected to be slightly higher under climate change. The changes in climate parameters are being felt globally in the form of changes in temperature and rainfall pattern. The global atmospheric concentration of carbon dioxide is largely responsible for global warming, which will reach up to 770 ppm in end of 2100. The total average impact may be positive or negative depending on the climatic scenarios. But most scenarios show that climate change will have an overall negative impact but not on Indian’s agriculture until 2050. By the year 2080 when temperature increase is very largely then Indian agriculture will suffer.