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

Abstract

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 pot^-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 CO₂ 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.