Sources Of Nicotine-N And Effects Of Nitrogen Supply On Growth, Nitrogen Uptake, Nicotine Contents In Nicotiana Tabacum Plants

In the present study, flue-cured tobacco cultivar (Nicotiana tabacum L. K 326) was selected to explored and investigate the origin of nicotine-N and their growth, nitrogen uptake and nicotine concentration (or contents) under different amounts of nitrogen supplies. The plants were grown either in nutrient solution in lab under the controlled condition or in quartz sand in greenhouse or in the field. This present study provided theoretic foundation for technical steps of controlling nicotine in flue-tobacco production. The main results were as followed:1. The peak of nitrogen uptake was not synchronous with that of nicotine accumulation in flue-cured tobacco. The peak of nitrogen uptake appeared before that of nicotine accumulation, and a lot of nicotine accumulation occurred after removal the apex.2. Nitrogen uptake before or after removal the apex was incorporated into nicotine biosynthesis in flue-cured tobacco. Moreover, nitrogen uptake after removal the apex was more important to nicotine biosynthesis in the later growing stages of flue-cured tobacco.3. Nitrogen supply after removing the apex could increase nitrogen concentration of leaves in flue-cured tobacco, especially in nicotine concentration of upper leaves and middle leaves.4. Proportion of fertilizer-N to total nicotine-N in leaves in the same growing stages took on decrease trends as leaf position increased. Proportion of fertilizer-N to total nicotine-N of each organ took on decrease trends as growing stages were processing. Soil-N took on contrary rules with fertilizer-N. Nitrogen absorbed from soil after removal the apex was more important to nicotine accumulations than nitrogen absorbed from fertilizer in both Yuxi site and Fenggang site, especially in Fenggang site.5. When flue-cured tobacco plants were cultivated by lower nitrogen level (1 mmol/L) , nitrogen uptake before removal the apex was more important for nicotine biosynthesis. When flue-cured tobacco plants were cultivated by high nitrogen level (6 mmol/L), Nitrogen uptake after removing the apex was more important for nicotine biosynthesis. When not-topping tobacco plants were cultivated by lower nitrogen level (1 mmol/L) , nitrogen uptake at early growing stages was more important for nicotine biosynthesis. When flue-cured tobacco plants were cultivated by high nitrogen level (6 mmol/L) , Nitrogen uptake at later growing stages was more important for nicotine biosynthesis.6. Nutrient solution results showed, when nitrogen supply after removal of apex was stopped, more nitrogen in lower leaves was exported and more nitrogen in the roots was imported. At the same time, great increased in nicotine concentration of leaves and in nicotine accumulations of whole tobacco plant. When plants were cultivated by high nitrogen level before removal the apex and stopped nitrogen supply after removal the apes, and more nitrogen in lower leaves of those plants was exported, and more nitrogen in the roots of those plants was imported, and greater increased in nicotine concentration of leaves of those plants.7. Field experiment results showed, there was significantly different between different amounts of nitrogen supplies and nicotine contents of three leaf positions and whole plant at each growing stages influe-cured tobacco, respectively. There was significantly different between different amounts of nitrogen supplies and nicotine concentration of lower leaves at each growing stages in flue-cured tobacco, respectively; but significantly different between different amounts of nitrogen supplies and nicotine concentration of upper leaves and middle leaves occurred only at early growing stages in flue-cured tobacco, not later growing stages.8. Nicotine biosynthesis took place with nitrogen consumed and roots developing. There were different stimulative effects of different amounts or concentations and different time of nitrogen supplies on roots developing and nitrogen uptake and nicotine accumulation respectively.