1Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi-110 012, India.
2School of Environment Management, GGS Indraprastha University, Kashmere Gate, Delhi, 110006, India.
3Division of Environmental Sciences, Indian Agricultural Research Institute, New Delhi-110 012, India.
4CIMMYT-India/RWC, CG Block, NASC Complex, DP Shastri Marg, New Delhi, 10 012, India.
5Water Resources Management Group, Regional Research Laboratory (CSIR), Bhopal-462026, India.
Tropospheric ozone (O3) is formed through a complex series of photochemical oxidative reaction involving oxides of nitrogen (NOx) and volatile organic compounds (VOC). There have been substantial levels of O3 found in many Indian cities, more in summer than winter and during noontime than other hours. Yield loss due to O3 may vary with types of crops, varieties, location and duration of exposure to O3 but in general, losses take place when the concentration goes higher than 40 ppbv with 7–12 hrs. of continuous exposure. Loss of yield can be compensated by elevated level of CO2 certainly up to a limit. Most of the exposure-response relationships were developed using controlled close- or open-top chamber experiments, which need to be translated to the crops grown in open field. However, the damage of crops by O3 in terms of reduced productivity and carbon assimilation (sequestration) may have far more implications, including our global climate policies.
Troposphoric ozone (O3), CC2, yield, crops
