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Nitrosamines and Plant Nutrition Dr. Gary Palmer University of Kentucky

Nitrosamines and Plant Nutrition Dr. Gary Palmer University of Kentucky. What are Nitrosamine?. Nitrogen containing compounds that are know to have a potential affect on cancer Those occurring in tobacco are specific to tobacco TSNA ( T obacco S pecific N itros A mines )

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Nitrosamines and Plant Nutrition Dr. Gary Palmer University of Kentucky

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  1. Nitrosamines and Plant Nutrition Dr. Gary Palmer University of Kentucky

  2. What are Nitrosamine? • Nitrogen containing compounds that are know to have a potential affect on cancer • Those occurring in tobacco are specific to tobacco • TSNA (Tobacco Specific NitrosAmines) • Occur during curing • Increase during storage of cured leaf

  3. Major Factors that Influence TSNA Accumulation • Curing Conditions • Related to rate of curing and moisture content • Storage • Related to moisture content and nitrogenous compounds • Nitrogen Fertilization • Rate? • Source? • Varietal Differences • Nornicotine • Nornicotine can

  4. Effect of 250 lb/a Nitrogen Fertilizer on Nicotine, Nitrate, Nitrite and TSNA Accumulation in Air-Cured Tobacco Lamina

  5. Nitrogen Source StudyHarrison Co. – Keith Smith Farm 112 kg/ha AN Broadcast Sidedressed with 168 kg/ha each, AN = AmmoniumNitrate, U= Urea, CN = Calcium Nitrate, SN = Sodium Nitrate

  6. Nitrate & Nitrite levels from different N sourcesHarrison Co. – Keith Smith Farm Lamina Mid-rib 112 kg/ha AN Broadcast Sidedressed with 168 kg/ha each, AN = AmmoniumNitrate, U= Urea, CN = Calcium Nitrate, SN = Sodium Nitrate

  7. Nitrosamine levels from different N sourcesHarrison Co. – Keith Smith Farm Lamina Mid-rib 112 kg/ha AN Broadcast Sidedressed with 168 kg/ha each, AN = AmmoniumNitrate, U= Urea, CN = Calcium Nitrate, SN = Sodium Nitrate

  8. Fertility TrialJackson Co. – Mike Huff Farm Broadcast Sidedress Number = kg of product/ha, AN = AmmoniumNitrate, CN = Calcium Nitrate, SN = Sodium Nitrate

  9. Nitrosamine levels from different N sourcesJackson Co. – Mike Huff Farm Lamina Mid-rib Broadcast Sidedress Number = lbs of product, AN = AmmoniumNitrate, CN = Calcium Nitrate, SN = Sodium Nitrate

  10. Nitrosamine levels from different N sourcesJackson Co. – Mike Huff Farm Mid-rib Lamina Broadcast Sidedress Number = lbs of product, AN = AmmoniumNitrate, CN = Calcium Nitrate, SN = Sodium Nitrate

  11. Effects of Nitrogen Rate on Burley Yield Madison Co. – Gregg Harris Farm 161 All plots received 450 lb/a Ammonium Nitrate Broadcast followed by the remainder of the nitrogen shortly after transplanting. AN = Ammonium Nitrate. 14-0-14 is a calcium/potassium nitrate mix

  12. Effects of Nitrogen Rate on Burley YieldShelby Co. – Gilbert Ray Tucker, Jr. Farm All plots received 450 lb/a Ammonium Nitrate Broadcast followed by the remainder of the nitrogen shortly after transplanting. AN = Ammonium Nitrate, MS=mid-season, LS=late season. Adding 714 lb/a 14-0-14 significantly improved yield over 450 lb/a alone

  13. Influence of Seed Source on TSNA Levels

  14. Screening Air-cured Varieties for Nornicotine Conversion • High levels of the nornicotine increases chance for high TSNA levels • A variety may have a high number of converters in a population • Conversion is Chemical Change of Nicotine to Nornicotine • By selection of non-converters, a “clean” line can be established

  15. Ethephon Treatment

  16. Screening (3%)

  17. Effect of Screening • Lowers mean conversion • does not necessarily eliminate all converter plants • most dramatic with high converters • reduced effect with low converters

  18. Effect of screening Screened Unscreened 57 5 VA 509 8 2 TN 90

  19. Bottom Line • Screened seed • lower nornicotine • will HELP reduce TSNAs – no guarantee • enable growers to meet manufacturers needs • Need to identify screened seedlots • can only do this by renaming screened varieties

  20. “LC” Varieties • Screened varieties • Re-released as “LC” varieties • “LC” varieties available to growers in 2005 • TN 90LC, TN 86LC, TN 97LC, KT 200LC, KY 907LC • NO difference except for conversion • Same for yield, quality, disease resistance • TN 90 “LC” is still TN 90

  21. Accumulation of TSNA during Storage

  22. Accumulation of TSNA during Storage • Air-curing experiments have shown that a substantial nitrite production during air-curing does not necessarily lead to high levels of TSNA in cured tobacco. • pH of the cured tobacco= 6 • Not an effective pH for reaction between alkaloids and nitrite • Other Nitrogenous compound may react with alkaloids even under dry conditions

  23. Avoiding TSNA accumulation during storage of cured tobacco • Good curing process with as low nitrite formation as possible • Tobacco in the bales should not be packed too tightly • Allows ventilation of nitrogenous compounds into atmosphere • Instead of reacting with alkaloids • Moisture content in the bales should be as low as possible • Prevent any chemical reactions and microbial growth

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