Response of rice production to elevated [CO2] and its interaction with rising temperature or nitrogen supply: a meta-analysis

Abstract

We used meta-analysis to synthesize 125 studies assessing the responses of rice production to elevated atmospheric carbon dioxide concentration ([CO2]), and the interaction of elevated [CO2] with rising temperature or N supply. Elevated [CO2] significantly enhanced rice yield by 20 %, despite no significant increase in grain size and harvest index at elevated [CO2]. Belowground biomass increased at elevated [CO2] to a larger extent than aboveground biomass. Among the Japonica, Indica and Hybrid rice cultivars, Hybrid cultivars generally showed the greatest growth response to elevated [CO2]. The maximum enhancement of rice yield was observed at 600–699 ppm [CO2] with less benefit in studies with lower or higher elevated [CO2] levels. Rice yield responses to elevated [CO2] were smaller in FACE compared with the other fumigation methods, largely associated with lower photosynthesis. Increases in rice yield at elevated [CO2] were constrained by limited N supply. The detrimental effect of rising temperature on spikelet fertility and harvest index were not be fully counteracted by elevated [CO2] effects. Together, the results of this meta-analysis suggest that rising [CO2] and warming accompanied by low N supply are unlikely to stimulate rice production, especially with the current trajectory of emissions scenarios.