关键词: 再生稻, 气候变化, 分布变迁, MaxEnt模型, 种植区, 适宜区

Abstract:

【Objective】The objective of this study was to simulate and predict the geographical distribution of ratoon rice in Sichuan-Chongqing region under climate change, thereby providing a scientific reference for regional expansion planning, cultivar breeding, and cropping-system formulation of ratoon rice in this area.【Method】Based on the past (1981-2000) 53 and current (2001-2020) 147 distribution points and 6 environmental variables of ratoon rice, the MaxEnt model was used to simulate the changes in the planting areas and potential suitable areas, and the dominant environmental variables affecting its distribution were determined.【Result】(1) The accumulated temperature during the safe growth period (Tac), the number of days during the safe growth period (Day), the average temperature in September (Tav₉), and altitude (Alt) were the dominant environmental variables affecting the geographical distribution pattern of ratoon rice. (2) From the past (1981-2000) to the current (2001-2020), the planting areas and potential suitable areas had extended toward the northwest of the basin, with an area expansion of 0.44×10⁴ km² (69.23%) and 3.25×10⁴ km² (60.89%), which located at 28°9'-30°55' N, 103°35'-108°32' E and 28°4'-31°48' N, 103°10'-110°4' E, respectively; the highly suitable area had extended northwest and northeast, mainly located at 28°7'-31°7' N and 103°26'-107°21' E, with a high degree of coupling with the distribution and changes of the planting area. (3) From the current (2001-2020) to the future (2041-2060), the suitable area was projected to expand northwestward under SSP245 and SSP585 scenarios. The northwestern boundary was expected to reach the area south of the central Chengdu to central Guangyuan, with the total suitable area increasing by 3.69%-16.92%. The highly suitable area was projected to extend northwestward to the line connecting Dongpo District of Meishan and Dachuan District of Dazhou, advancing 1.4°N (155.65 km) northward and 0.8°E (88.94 km) westward, with the area increasing by 45.24%-65.18%. Conversely, portions of the highly suitable area in central Yibin (Sichuan) and in Qijiang, Rongchang, and Dazu (Chongqing) were expected to contract by 2.68%-11.90%. The unchanged areas were mainly concentrated in southern Sichuan and western Chongqing regions, accounting for 72.32%-88.10% of the baseline highly suitable area.【Conclusion】Climate change was generally conducive to the expansion of suitable areas for ratoon rice in the Sichuan-Chongqing region. The primary driver was the concurrent increase in accumulated temperature and number of days during the safe growth period. Priority should therefore be given to consolidating the traditional advantageous areas in southern Sichuan and western Chongqing. Expansion should proceed incrementally into the new suitable areas, notably northeastern Leshan, western and eastern Ziyang, southern Suining, southern Nanchong, southwestern Dazhou in Sichuan, as well as the most of Tongnan and northern Tongliang in Chongqing. Pilot cultivation should be encouraged in emerging potential areas, such as eastern Chengdu, Deyang, and southern Mianyang. A phased, region-specific strategy was recommended to ensure the sustainable and stable development of ratoon rice production. Concurrently, intensified efforts were needed to develop and deploy monitoring, early-warning, and risk-mitigation technologies against meteorological disasters under continued global warming.

Key words: ratoon rice, climate change, distribution change, MaxEnt model, plant area, suitable areas