Growth and nitrogen allocation of dry season tropical rice as a result of carbon dioxide fertilization and elevated night time temperature

A field experiment was laid out on carbon dioxide (CO2) fertilization for 3 years in dry cropping seasons to investigate the effects of elevated CO2 (e-CO2) (550 A mu mol mol(-1)) and elevated CO2 (550 A mu mol mol(-1)) + elevated temperature (+2 A degrees C over ambient) (e-CO2 + T) on biomass production, carbon (C) and nitrogen (N) concentration in plant parts, its allocation and grain quality in a tropical rice (cultivar-Naveen) under open top chambers (OTCs). The aboveground plant biomass, root biomass, leaf area index and net C assimilation rates were increased significantly under e-CO2 to that of ambient CO2 in control chamber CC by 32, 26, 21 and 37 %, respectively over the three dry cropping seasons. The grain yield was significantly higher under e-CO2 compared to CC (21.6 %), although the higher temperature in e-CO2 + T significantly reduced the yield advantage by 8.5 % overe-CO2. The amylose content was significantly increased by 10 % under e-CO2 + T over CC. In dry season, CO2 fertilization enhanced the rice yield by 21.6 % but the yield advantage of CO2 fertilization were reduced by 8.5 % due to elevated temperature. We did not found any deterioration ingrain quality in elevated temperature (2 A degrees C) in low land rice ecologies.