Emission of greenhouse gases and yield-scaled global warming potential of rice cultivars under permanent and intermittent irrigation

Irrigated rice cultivation is an important source of greenhouse gas emissions. Among the main greenhouse gases, there are carbon dioxide, methane, and nitrous oxide, with the emission of each gas varying according to the management of the crop, cultivar and irrigation management. In this context, the present study aimed to quantify the partial global warming potential (pGWP) measured by CH4 and N2O emissions in conventional and hybrid cultivars under two irrigation management, as well as the relation with grain yield (pGWP/Y). For this, a field experiment was conducted during the 2016/17 and 2017/18 crop seasons, with an experimental design of randomized blocks in a factorial arrangement (2x4), with four replications using water and rice cultivars. The water was managed through permanent and intermittent irrigation, with one conventional cultivar (IRGA 424 RI) and three hybrid cultivars (XP 113, Titan CL and Lexus CL). The pGWP can be reduced by up to 18% depending on the cultivar used and 11.8% through the adoption of intermittent irrigation management. More than 90% of the pGWP is due to methane emission, and the management actions of the rice crop should be directed towards the mitigation of this gas. In relation to the pGWP/Y index, the cultivar XP 113 had presented the best results.