Balancing yield and wrapper leaf quality in cigar tobacco through data-driven nitrogen management

Nitrogen (N) is a vital macronutrient influencing both the yield and quality of cigar tobacco leaves, particularly the high-value wrapper leaves. However, the response of cigar wrapper yield and quality traits to N input remains inconsistent and underexplored. This study aims to identify an optimal N application rate that balances productivity and leaf quality for sustainable cigar wrapper cultivation. A two-year field experiment was conducted using the cigar tobacco cultivar Chuxue 26 to evaluate the effects of six N rates (0–270 kg N/ha) on yield and multiple quality parameters. Results showed that total yield, as well as wrapper and binder yields, increased with N rate, while filler yield declined. N also significantly influenced key quality traits. Apparent quality and oil content initially improved but declined beyond 180 kg N/ha. Leaf thickness increased with N application up to 135 kg N/ha and then declined, while stalk-containing rate and particulate matter content decreased with higher N input. Blade tension peaked at 135 kg N/ha. The potassium-chlorine ratio increased with N application, whereas the glycoalkaloid ratio declined. Using analytic hierarchy process and membership function methods, the optimal N application rate was identified as a local recommendation of 187.4 kg N/ha (recommended range: 170–200 kg N/ha) for the cigar tobacco cultivar Chuxue 26 under the agroecological conditions of northwestern Hubei Province. This rate provides a balanced, data-driven recommendation for enhancing both yield and wrapper quality in cigar tobacco production.