Abstract: We conducted a field experiment on three rice cultivation patterns, namely ratoon rice, single-cropping rice, and double-cropping rice, using hybrid rice and conventional rice varieties as materials in 2021-2022. We evaluated the ecological efficiency differences across rice cultivation patterns from multiple dimensions, including yield and material distribution, greenhouse gas emissions, carbon nitrogen footprint, and carbon balance, using closed static greenhouse gas collection and life cycle assessment methods. The results showed that the ratoon rice pattern had the highest average yield and daily average yield, followed by the double-cropping rice pattern with the lowest daily average yield, and the lowest single-cropping yield ranking second in daily average yield. In the rice ratooning system, non-structural carbohydrate (NSC) translocation amount and translocation rate in various plant parts were significantly higher in ratoon season rice than in its main crop, single-cropping rice, and both early and late crops of double-cropping rice. Across all organs, the average contribution of NSC remobilization to grain yield formation was 7.5% over the two years, being 19.9% and 12.8% higher than that of the main crop and single-cropping rice, respectively, and 67.0% and 77.0% greater than that of early and late rice in the double-cropping system. Compared with the single-cropping and double-cropping, the ratoon rice reduced CO₂ emission intensity by 2.3%-725.0% and 6.8%-732.6% in 2021 and 2022, CH₄ emission intensity by 31.2%-751.8% and 27.6%-746.4%, N₂O emission intensity by 7.4% and 4.6%, resource utilization efficiency by 23.5%-24.6% and 57.4%-57.5%, and daily economic benefits by 36.0%-35.7% and 81.9%-101.9%, respectively. In 2021 and 2022, the carbon footprint of the ratoon rice pattern increased by 31.2% and 11.2% respectively compared to single-cropping rice, and decreased by 19.1% and 28.2% respectively compared to double-cropping rice. The nitrogen footprint increased by 44.2% and 46.8% compared to single-cropping rice, and decreased by 10.1% and 15.4% compared to double-cropping rice. The carbon budget surplus of ratoon, single-cropping, and double-cropping rice were 24623.5, 13342.6, and 23772.2 kg CO₂-eq·hm^-2, respectively. It is suggested that the ratoon rice, especially the regenerated season rice, has high daily yield and low greenhouse gas emission intensity per unit yield, achieving stronger synergy between yield and carbon surplus, which is a sustainable, ecologically efficient, and environmentally friendly cropping system well-suited to rice production in Southeast China.

Key words: ratoon rice, single-cropping rice, double-cropping rice, yield, carbon budget balance, carbon sequestration and emission reduction, carbon and nitrogen footprint