Spatial suitability and expansion potential of ratoon Rice for nature-based climate-resilient farming in Fujian Province, Southeast China under climate warming

Ratoon rice offers a nature-based solution for agricultural sustainable intensification by utilizing in situ biological processes to improve resource-use efficiency without proportionally increasing external inputs. However, the spatial suitability and expansion potential of ratoon rice under climate warming—particularly concerning safe growth periods and accumulated temperature—remain insufficiently quantified. This study aims to develop an integrated assessment framework to evaluate the spatial suitability and expansion potential of ratoon rice in Southeast China under changing climatic conditions from 1990 to 2024, with a focused case study on Fujian Province as a representative region for ratoon rice production in South China. We combined a 35-year climate dataset with soil indicators (microbial biomass carbon and erosion risk) and irrigation capacity. The data were analyzed using Sen–Mann–Kendall trend analysis, the CatBoost algorithm, and multi-criteria decision-making methods. The analysis reveals: (1) the safe growth period for ratoon rice in Fujian Province ranges from 87 to 234 days; (2) from 1990 to 2024, a warming trend (0.0367–0.6423 °C per decade) was observed across the entire province, with a “warm-wet” pattern in the northwest and a “warm-dry” trend in the southeast; (3) 18 suitability subzones were identified based on ratoon rice transplanting mode (GC, greenhouse seedling culture-transplanting mode; FC, field seedling culture-transplanting mode), maturity type (early-, medium-, and late-maturing), and three suitability classes (highly suitable, moderately suitable, and generally suitable). The provincial-scale total suitable area for ratoon rice reached 737.78 × 10 4 ha, accounting for 60.30% of the provincial land area. The average standard climate and climate-soil production potentials of suitable areas were 19,954.16 kg ha −1 and 13,493.80 kg ha −1 , respectively. From 1990 to 1999 to 2010–2024, the suitable area increased by 33.00 × 10 4 ha, with the overall distribution expanding northward and toward higher elevations; and (4) Within existing cultivated land of Fujian Province, 410,167.50 ha are suitable for ratoon rice development, accounting for 62.55% of the total cultivated land area, including 214,187.07 ha under GC mode and 195,980.43 ha under FC mode. Ratoon rice represents a scalable, nature-based pathway for climate-resilient agriculture in Southeast China. The delineated suitability subzones provide a scientific basis for spatial planning and for matching ratoon rice maturity types with specific local conditions. Strategic scaling—supported by locally adapted maturity-type selection and targeted policies—can significantly enhance regional food security and deliver substantial eco-economic benefits in the context of ongoing climate change, providing a replicable case for similar studies in other regions.