Effect of rice plants on CH4 production, transport, oxidation and emission in rice paddy soil

Abstract

To understand the integrated effects of rice plants (variety Wuyugeng 2) on CH4 emission during the typical rice growth stage, the production, oxidation and emission of methane related to rice plants were investigated simultaneously through laboratory and greenhouse experiments. CH4 emission was significantly higher from the rice planted treatment than from the unplanted treatment. In the rice planted treatment, CH4 emission was higher at tillering stage than at panicle initiation stage. An average of 36.3% and 54.7% of CH4 produced was oxidized in the rhizosphere at rice tillering stage and panicle initiation stage, respectively, measured by using methyl fluoride (MF) technique. In the meantime, CH4 production in the planted treatments incubated under O2-free N2 condition was reduced by 44.9 and 22.3%, respectively, compared to unplanted treatment. On the contrary, the presence of rice plants strongly stimulated CH4 production by approximately 72.3% at rice ripening stage. CH4 emission through rice plants averaged 95% at the tillering stage and 89% at the panicle initiation stage. Based on these results, conclusions are drawn that higher CH4 emission from the planted treatment than from unplanted treatment could be attributed to the function of rice plants for transporting CH4 from belowground to the atmosphere at tillering and panicle initiation stage, and that a higher CH4 emission at tillering stage than at panicle initiation stage is due to the lower rhizospheric CH4 oxidation and more effective transport mediated by rice plants.