Neophytadiene variation in tobacco reflects strong spatial and climatic control with limited soil contribution

Neophytadiene, a volatile diterpenoid compound widely present in tobacco leaves, plays a critical role in determining aroma quality. However, the relationship between its content variation and environmental factors remains poorly understood. In this study, we conducted field sampling across different ecological zones in China and quantified neophytadiene concentrations in tobacco leaves using gas chromatography. By integrating multi-source environmental data, we examined the correlations between neophytadiene levels and spatial, climatic, and soil variables. The results revealed significant spatial differences in neophytadiene concentrations. Neophytadiene content was negatively correlated with both latitude and longitude, but positively correlated with altitude. Among climatic factors, higher growing season average temperature and total precipitation, and shorter growing season sunshine duration were associated with increased neophytadiene accumulation. Among soil properties, only soil pH exhibited a consistent negative correlation with neophytadiene levels. Structural equation modeling further demonstrated that geographic variables indirectly influenced neophytadiene content through their effects on climate conditions, which subsequently altered soil pH, ultimately affecting neophytadiene biosynthesis. These findings clarify the environmental regulation pathways of neophytadiene accumulation and provide a theoretical basis for identifying high-quality tobacco production areas and optimizing regional cultivation strategies.