Greenhouse gas emissions from ratoon rice fields among different varieties

Abstract

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 CH 4 and N 2 O 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 CH 4 and N 2 O 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 CH 4 emissions during the RR seasons was caused by low temperature, short growth period, and low aboveground biomass. Considering both CH 4 and N 2 O emissions, the global warming potential of JLY was as high as 10.95 t CO 2 -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 CO 2 -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. • Compared with the MR seasons, CH 4 and N 2 O emissions decreased in the RR seasons. • CH 4 emissions were responsible for 84–90% of GWP during the whole seasons. • There was a significant positive correlation between yields of RR and straw biomass of MR. • The variety JLY has the highest yield and the lowest GHGI.