Recent Advancements in Tobacco Production and Composition in Tennessee and Kentucky.

Although tobacco acreage has declined in Kentucky and Tennessee since the Fair and Equitable Tobacco Reform Act of 2004 was signed into law, tobacco continues to be an important crop in these states. Sustained research efforts have resulted in improved tobacco production and quality and significantly reduced tobacco-specific nitrosamines (TSNA). TSNA reduction is of particular importance due to the current emphasis on the health risks of tobacco. Over the last ten years, TSNA reduction practices resulting from this research have been incorporated into state tobacco production recommendations. Some of the most significant research and subsequently implemented practices to reduce TSNAs while maintaining high yields and quality include the following: screening and selection of tobacco varieties with low conversion of nicotine to nornicotine, a TSNA precursor; reducing the amount of total nitrogen applied to the crop without reducing yields; harvesting at maturity rather than allowing tobacco to stand past maturity; avoiding the harvest or storage of tobacco with free moisture on leaves; after harvest, spacing plants evenly on the stick and sticks evenly in curing structures as to avoid over-packing; minimizing the length of storage of tobacco and keeping moisture in the stored leaf as low as possible; in air-cured tobacco, maintaining the balance between adequate moisture for high leaf quality and adequate ventilation for reduced TSNAs; in fire-cured tobacco, timely fire-curing no more than necessary at temperatures below 130 degrees F. Additionally, ongoing research indicates that the introgression of the demethylase mutations into tobacco varieties will further reduce TSNA levels while maintaining yield potential and quality.