Growth, yield and nitrogen uptake in rice crop grown under elevated carbon dioxide and different doses of nitrogen fertilizer

Climate change associated with rising atmospheric carbon dioxide (CO2) concentration may have impact on crop production and soil health. Increase in atmospheric CO2 concentration may enhance crop growth with higher demand for nutrients by the crop. An experiment was conducted during July-October, 2013 using Free Air Carbon Dioxide Enrichment facility at the Indian Agricultural Research Institute, New Delhi to study the impact of elevated CO2 and nitrogen (N) dose on growth, yield and nitrogen uptake in rice crop. Four doses of N, i.e., control, 0.6 g N pol(-1 )(75% recommended dose of N), 0.8 g N pot(-1 )(100% recommended dose of N) and 1.0 g N pot(-1) (125% recommended dose of N) were applied in both ambient (395 ppm) and elevated CO2 (550 +/- 20 ppm) conditions. Grain and biomass yield of rice was significantly higher under elevated CO(2 )condition. Plant growth and yield parameters also increased with increased N doses in both elevated and ambient CO2 conditions. Nitrogen concentration of grain and straw decreased under high CO2 level but N uptake increased under elevated CO2 condition. Agronomic efficiency of N was higher under elevated CO2 while recovery efficiency of N remained unaffected. The study showed that although yield of rice increases under elevated CO2 condition, to maintain plant nitrogen concentration, application of additional dose of N is required.