H. Bisht - Water Technology Centre, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, India.
Shaloo - Water Technology Centre, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, India.
B. Kumar - Water Technology Centre, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, India.
D. K. Singh - Water Technology Centre, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, India.
A. K. Mishra - Water Technology Centre, ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, India.

This study was conducted to examine the sensitivity of weather parameters and CO۲ concentration to wheat production under two irrigation regimes viz. full irrigation and limited irrigation, using CERES-Wheat model. Field experiment data from the ۲۰۱۶-۱۷ and ۲۰۱۷-۱۸ rabi seasons on wheat cultivar HD-۲۹۶۷ with three sowing dates and five irrigation regimes were used to calibrate and validate the CERES-Wheat crop simulation model. Validation results indicated very good agreement between simulated and observed values under five, four, and three irrigations regimes as compared to lower irrigation regimes. Under full irrigation and limited irrigation, grain yield sensitivity to incremental unit of mean temperature from ۱ to ۳°C revealed a decrease of ۶ to ۲۲% and ۸ to ۱۶%, respectively. Temperature decreases of ۱-۳°C resulted in a gradual increase in yield of ۱۰-۲۸ and ۶.۵- ۲۰%, respectively, under full and limited irrigation. The combined effect of higher mean temperature and lower solar radiation revealed that wheat yield was more sensitive to temperature than solar radiation. Furthermore, the combined effect of mean temperature and CO۲ level revealed that higher levels of CO۲ concentration yielded the greatest benefits with a ۱ °C increase in temperature, but further increases in temperature reduced the beneficial effect of elevated CO۲ level under both irrigation conditions.

CO۲ concentration, DSSAT, Food security, Solar radiation, Temperature effects