Sustaining low TSNA levels in Malawi Burley tobacco using the LC Protocol
Burley tobacco has variable levels of conversion of nicotine to nornicotine, the precursor for the main Burley tobacco specific nitrosamine (TSNA), N’-nitrosonornicotine (NNN). Malawian tobacco is inherently low in TSNA levels, affording a competitive advantage over tobacco from elsewhere around the world, particularly if legislation is introduced limiting TSNA levels in cigarettes. Because of global concerns about TSNAs in the international tobacco trade, Agricultural Research and Extension Trust (ARET) considers that an opportunity exists to continue reducing TSNA levels in Malawi tobacco, eventually improving its competitiveness by introducing low converter (LC) technology. The study aimed at introducing LC methodology and establishing the conversion status of ARET’s varieties. Activities included technical and analytical support in seed production planning, field sampling and alkaloid analysis by partners from the University of Kentucky (UKY) funded by Phillip Morris International. Seven previously unscreened varieties were grown alongside a high converter check in the 2016/17 season. Individual plants were sampled according to the LC protocol and analysed for alkaloids. Results revealed variable, but generally low, rates of conversion in Malawi Burley varieties. Conversion was 1.0-99.2 % in male fertile lines and 1.0-79.9 % in male sterile lines compared to 90.5-99.1 % for the high converter check, TN 90H, indicating satisfactory sampling and curing. The varieties are now LC screened and available for certified seed production. Integrating such best practices in seed provision with promotion of other seed and leaf integrity and traceability initiatives will help enhance compliance, competitiveness and maintain Malawi as a desirable origin for reduced-risk tobacco for sustainability in the global marketplace.