Carbon Di Oxide Fertilization: Effects on Plant Productivity

Increasing Carbon dioxide (CO ) is an important component of global climate change that 2 has drawn the attention of environmentalists worldwide in the last few decades. Besides acting as an important greenhouse gas, it also produces a stimulatory effect, its instantaneous impact being a significant increase in the plant productivity. Atmospheric CO levels have linearly increased from approximately 280 parts per million (ppm) 2 during pre-industrial times to the current level of more than 390 ppm. In past few years, anthropogenic activities led to a rapid increase in global CO concentration. Current 2 Intergovernmental Panel on Climate Change (IPCC) projection indicates that atmospheric CO concentration will increase over this century, reaching 730-1020 ppm 2 by 2100. An increase in global temperature, ranging from 1.1 to 6.4oC depending on global emission scenarios, will accompany the rise in atmospheric CO . As CO acts as a 2 2 limiting factor in photosynthesis, the immediate effect of increasing atmospheric CO is 2 improved plant productivity, a feature commonly termed as “CO fertilization”. Variability 2 in crop responses to the elevated CO made the agricultural productivity and food 2 security vulnerable to the climate change. Several studies have shown significant CO 2 fertilization effect on crop growth and yield. An increase of 30 % in plant growth and yield has been reported when CO concentration has been doubled from 330 to 660 ppm. 2 However, the fertilization effect of elevated CO is not very much effective in case of C 2 4 plants which already contain a CO concentration mechanism, owing to their specific leaf 2 anatomy called kranz anatomy. As a result, yield increments observed in C plants are 4 comparatively lower than the C plants under similar elevated CO concentrations. This 3 2 review discusses the trends and the causes of increasing CO concentration in the 2 atmosphere, its effects on the crop productivity and the discrepancies in the response of C and C plants to increasing CO concentrations.