Wheat grown under elevated CO2 was more responsive to nitrogen fertilizer in Eastern India

Abstract

Abstract Elevated CO2 might have differential impact on the growth, development, and yield of wheat under varying nutrient management, especially in a warmer climate when the global atmospheric temperature is already increasing. Field experiments were conducted in subtropical Eastern India during the rabi seasons of 2014–2016 to study the performance of wheat under the elevated CO2 environment with different nitrogen (N) management. Wheat was grown in open field and inside open top chambers (OTCs) with ambient (˜390 μmol mol−1) and elevated (˜585 μmol mol−1) level of CO2 without any fertilizer addition (N0), and with application of N through chemical fertilizer (CF) at normal (100%) recommendation [N100(CF)] and 50% higher dose [N150(CF)] and through integration of organic and chemical fertilizer [N150(OF + CF)]. Results showed that CO2 enrichment had a positive effect on various growth parameters and yield attributes of wheat. Elevated CO2 tended to increase the crop growth rate and the fraction of leaf biomass and leaf N, especially for the N management using chemical fertilizer [N100(CF) and N150(CF)]. Elevated CO2 [+˜200 μmol mol−1] caused 17% increase in wheat grain yield above ambient as averaged over the N fertilized treatments. Application of N at 50% higher dose than normal through CF did not increase the grain yield significantly under the open field and OTC with ambient [CO2] environment, whereas the yield increment was significant under the elevated [CO2] environment. Elevated CO2 also resulted in higher agronomic N use efficiency and nitrogen harvest index with the increased N fertilizer dose. Thus, wheat production under the elevated CO2 environment in Eastern India might be maintained or improved through the normal and increased dose of N fertilizer application.