Studies of Low-Nicotine Flue-Cured Tobacco Production
Flue-cured tobacco (Nicotiana tabacum) has been managed to optimize the yield of high-quality cured leaf while maintaining nicotine levels within a relatively narrow range based on the Regional Minimum Standards Program. Among the 3,000 plus alkaloids found in tobacco, nicotine accounts for greater than 90% of the total alkaloids produced in commercial tobacco varieties. Precious research has demonstrated an association with nicotine levels and cured leaf yield and quality. On March 16, 2018, the Food and Drug Administration issued a notice for proposed rulemaking to limit nicotine in combustible cigarettes to 0.3-0.5 mg nicotine per gram of tobacco (an approx. 98% reduction from current levels). Studies on achieving decreased levels of nicotine in flue-cured tobacco have been conducted since the mid-1900's and some success has been found through breeding and genetics. The FDA proposal suggested changes to standard agronomic production practices as a means of achieving their proposed nicotine levels. The primary objectives of this work are: (1) evaluate the impact of standard agronomic production practices on nicotine levels and the resulting yield and cured leaf quality and (2) quantify differences in nitrogen-use efficiency between conventional and low-nicotine flue-cured tobacco varieties. Results showed that the changes to production practices did not sufficiently lower nicotine levels to the range proposed by the FDA. The only publicly available low-nicotine variety, LA FC53, did not achieve the targeted nicotine level and the yield and cured leaf quality was severely reduced. The study of nitrogen-use efficiency quantified differences between conventional and low-nicotine flue-cured tobacco varieties. Proprietary, low-nicotine varieties developed from K 326 tended to have lower nicotine levels than LA FC53 with improved yield and cured leaf quality. Both yield and quality are associated with nitrogen-use efficiency and the nitrogen-use efficiency of the new low-nicotine lines was comparable to K 326 and better than the previously developed, low-nicotine standard variety. No evaluation of smoking characteristics of the cured tobacco from these studies was conducted and would be necessary for commercial utilization of low-nicotine flue-cured tobacco.