Greenhouse gas emissions from ratoon rice fields among different varieties

Ratoon rice (RR) is a practice originating from the stubble left after the previous main rice crop (MR) harvested. Planting RR is of great significance to increase grain production and ensure food security. However, few reports are available on the response of RR varieties to greenhouse gas emissions. A field experiment was conducted to comprehensively estimate the CH4 and N2O emissions among RR varieties in Southwest China. Five varieties were adopted in the experiment: Hanyou 73 (HY), Taiyou 390 (TY), Jingliangyouhuazhan (JLY), Yuxiang 203 (YX), and Fengliangyouxiangyihao (FLY). The CH4 and N2O emissions from the RR seasons accounted for 23–24% and 10–27% of total emissions from the MR+RR seasons, respectively. The significant reduction in CH4 emissions during the RR seasons was caused by low temperature, short growth period, and low aboveground biomass. Considering both CH4 and N2O emissions, the global warming potential of JLY was as high as 10.95 t CO2-eq ha–1 in the MR+RR seasons, but the total yields were significantly higher than those of other varieties by 8–16%, and thereby the greenhouse gas intensity (GHGI) of JLY was the lowest at 1.10 t CO2-eq t–1 yield. The findings demonstrate that JLY is a suitable ratoon rice variety with the highest yield and lowest GHGI. Furthermore, it is possible to reduce greenhouse gas emissions through the innovation of high-yielding rice varieties to adapt to future climate changes and ensure food security.