Super Rice Cropping Will Enhance Rice Yield and Reduce CH4 Emission： A Case Study in Nanjing,China

A pot experiment was performed to learn the differences in plant productivity and CH₄ emission between two rice cultivars, super rice variety Ningjing 1 and traditional variety Zhendao 11, which were currently commercially applied in Nanjing, China. Similar seasonal changes of CH₄ emission fluxes and soil solution CH₄ contents were found between the tested cultivars. Although there was no significant difference in plant biomass production between the cultivars, the grain yield of Ningjing 1 was significantly higher by 35.0% (P < 0.05) than that of Zhendao 11, whereas the total CH₄ emission from Ningjing 1 was 35.2% lower (P < 0.05). The main difference in the amounts of CH₄ emission between the cultivars occurred in the period from the tillering stage to the heading stage. The biomass-scaled and yield-scaled CH₄ emissions were respectively 3.8 and 5.2 mg/g for Ningjing 1, significantly lower than those for Zhendao 11 (7.4 and 12.8 mg/g, respectively). According to the relationships between the plant growth characteristics and the CH₄ emission, a stronger root system contributed mainly to the lower CH₄ emission of Ningjing 1, as compared with Zhendao 11. Our results demonstrated that super rice has advantages not only in grain productivity but also in CH₄ emission mitigation. Further expansion of super rice cropping will enhance rice yield and reduce greenhouse gas emission in China.