Nicotiana tabacum commercial cultivation

Nicotiana tabacum is the principal source of nicotine. The stems and leaves of the plant are used for commercial purposes. Tobacco is now cultivated in many countries of the world. 

These alkaloids were mostly found in crude nicotine obtained commercially by treating the leaves of cultivated tobacco Nicotiana tabacum L. and sometimes N. rustica L.) with an aqueous solution of an alkali and distilling with steam (265). The total nicotine content of the tobacco plant is distributed as follows flowers, 5%, stems 18%, roots 13%, and leaves 64% (266). There is considerable variation in the nicotine content of different varieties of tobacco, but there is a close parallelism in the plant between nicotine and citric acid. Nicotine in the plant, however, is not always combined with an organic acid. The glucoside tabacilin yields glucose, nicotine, and other substances (267) when hydrolyzed while the tobacco glucoside tabacin yields nicotine when treated with alkalis (268). 

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