Climate drivers of nicotine content variation and ARIMA model prediction

To investigate the climate-driven mechanism of nicotine formation, this study was based on flue-cured tobacco leaf samples (n=5321) and corresponding climate data from three major typical tobacco-growing regions in China—Southwest, Huanghuai, and Northeast—from 2010 to 2024. Methods including analysis of variance, Mantel test, variance partitioning, correlation analysis, and ARIMA time series models were employed to systematically analyze the contribution rates and interactions of production region, cultivar, leaf position, and climatic factors on nicotine content. The results showed an overall increasing trend in nicotine content across leaf positions in the Southwest region, with upper and middle leaves increasing by 20.3% and 16.7%, respectively, over the 10-year period. The Huanghuai and Northeast regions exhibited decreasing trends in nicotine content. The climatic drivers of nicotine content differed significantly among leaf positions. Nicotine in upper leaves was primarily regulated by sunshine duration (contribution rate 42.5%), while nicotine in middle and lower leaves was driven by precipitation. Time series analysis indicated a significant decrease in sunshine duration in the Southwest region at a rate of 2.1 hours per year (p<0.05), and increasing precipitation trends of 21 mm and 17 mm per year in the Huanghuai and Northeast regions, respectively. Based on ARIMA model, the nicotine content of upper leaves in the Southwest region is projected to rise to 3.6–3.8% over the next five years, posing a risk of exceeding the suitable range for industrial availability. The response of nicotine to climatic factors showed significant cultivar specificity. Yunyan 87 was sensitive to sunshine and precipitation, while Yunyan 99, Zhongyan 100, and Longjiang 911 were insensitive to sunshine duration. This study utilized ARIMA models to predict and issue an early warning that nicotine content in upper leaves of the Southwest region risks exceeding standards in the next five years, providing a critical window for proactive industry response. The identified climate-resilient cultivars such as 'Yunyan 97' and 'Longjiang 911' establish a germplasm foundation for ensuring the future quality stability and industrial usability of tobacco leaf raw materials.