M. Maniruzzaman

Effect of Elevated Air Temperature and Carbon Dioxide Levels on Dry Season Irrigated Rice Productivity in Bangladesh

Agricultural productivity is affected by air temperature and CO2 concentration. The relationships among grain yields of dry season irrigated rice (Boro) varieties (BRRI dhan28, BRRI dhan29 and BRRI dhan58) with increased temperatures and CO2 concentrations were investigated for futuristic crop management in six regions of Bangladesh using CERES-Rice model (DSSATv4.6). Maximum and minimum temperature increase rates considered were 0°C, +1°C, +2°C, +3°C and +4°C and CO2 concentrations were ambient (380), 421, 538, 670 and 936 ppm. At ambient temperature and CO2 concentration, attainable grain yields varied from 6506 to 8076 kg·ha-1 depending on rice varieties. In general, grain yield reduction would be the highest (13% - 23%) if temperature rises by 4°C and growth duration reduction would be 23 - 33 days. Grain yield reductions with 1°C, 2°C and 3°C rise in temperature are likely to be compensated by increased CO2 levels of 421, 538 and 670 ppm, respectively. In future, the highest reduction in grain yield and growth duration would be in cooler region and the least in warmer saline region of the country. Appropriate adaptive techniques like shifting in planting dates, water and nitrogen fertilizer management would be needed to overcome climate change impacts on rice production.