Nicotiana tabacum

Nicotiana tabacum
Scientific classification
Kingdom: Plantae
(unranked): Eudicots
(unranked): Asterids
Order: Solanales
Family: Solanaceae
Genus: Nicotiana
Species: N. tabacum
Binomial name
Nicotiana tabacum
L.

Nicotiana tabacum, or cultivated tobacco, is an annually-grown herbaceous plant. It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco. It grows to heights between 1 and 2 meters. Research is ongoing into its ancestry among wild Nicotiana species, but it is believed to be a hybrid of Nicotiana sylvestris, Nicotiana tomentosiformis, and possibly Nicotiana otophora.[1]

History

In their great first voyage to the New World, Christopher Columbus and his expedition were introduced to a plant whose smoke was called tobacco by the natives of Hispaniola. In 1560, Jean Nicot de Villemain brought tobacco seeds and leaves as a "wonder drug" to the French court. In 1586 the botanist Jaques Dalechamps gave the plant the name of Herba nicotiana, which was also adopted by Linné. It was considered a decorative plant at first, then a panacea, before it became a common snuff and tobacco plant. Tobacco arrived in Africa at the beginning of the 17th century. The leaf extract was a popular pest control method up to the beginning of the 20th century. In 1851, the Belgian chemist Jean Stas documented the use of tobacco extract as a murder poison. The Belgian count Hippolyte Visart de Bocarmé had poisoned his brother-in-law with tobacco leaf extract in order to acquire some urgently needed money. This was the first exact proof of alkaloids in forensic medicine.[2]

Geographical distribution

N. tabacum is a native of tropical and subtropical America but it is now commercially cultivated worldwide. Other varieties are cultivated as ornamental plants or grow as a weed.

Habitat and ecology

N. tabacum is sensitive to temperature, air, ground humidity and the type of land. Temperatures of 20–30 °C (68–86 °F) are best for adequate growth; an atmospheric humidity of 80 to 85% and soil without a high level of nitrogen are also optimal.

Botanical description

Nicotiana tabacum Linné is a robust annual little branched herb up to 2.5 m (8.2 ft) high with large green leaves and long trumpet-shaped white-pinkish flowers. All parts are sticky, covered with short viscid-glandular hairs, which exude a yellow secretion containing nicotine.

Leaves

Tobacco leaf surface under an optical microscope, magnification 100x:
1. Trichomes
2. Epidermal cells
3. Stomata

Varied in size, the lower leaves are the largest at up to 60 cm (24 in) long, shortly stalked or unstalked, oblonged-elliptic, shortly acuminate at the apex, decurrent at the base, the following leaves decrease in size, the upper one sessile and smallest, oblong- lanceolate or elliptic.

Flowers

In terminal, many flowered inflorescences, the tube 5–6 cm (2.0–2.4 in) long, 5 mm (0.20 in) in diameter, expanded in the lower third (calyx) and upper third (throat), lobes broadly triangular, white-pinkish with pale violet or carmine colored tips tube yellowish white; calyx with five narrowly triangular lobes which are 1.5–2 cm (0.59–0.79 in) long. A capsular ovoid or ellipsoid, surrounded by the persistent calyx and with a short apical beak, about 2 cm (0.79 in) long. Seeds are very numerous, very small, ovoid or kidney shaped, brown.

Part used

Every part of the plant except the seed contains nicotine, but the concentration is related to different factors such as species, type of land, culture and weather conditions. The concentration of nicotine increases with the age of the plant. Tobacco leaves contain 2 to 8% nicotine combined as malate or citrate. The distribution of the nicotine in the mature plant is widely variable: 64% of the total nicotine exists in the leaves, 18% in the stem, 13% in the root, and 5% in the flowers.

Phytochemicals

Tobacco contains the following phytochemicals: nicotine, anatabine, anabasine (an alkaloid similar to the nicotine but less active), glucosides (tabacinine, tabacine), 2,3,6-trimethyl-1,4-naphthoquinone, 2-methylquinone, 2-napthylamine, propionic acid, anatalline, anthalin, anethole, acrolein, anatabine, cembrene, choline, nicotelline, nicotianine, and pyrene.

Ethnomedicinal uses

The regions that have histories of use of the plant include:

Other uses

A protein of the White–Brown complex subfamily[4] can be extracted from the leaves. It is an odourless, tasteless white powder and can be added to cereal grains, vegetables, soft drinks and other foods. It can be whipped like egg whites, liquefied or gelled and can take on the flavour and texture of a variety of foods. It is 99.5% protein, contains no salt, fat or cholesterol. It is currently being tested as a low calorie substitute for mayonnaise and whipped cream.

Main use

All parts of the plant contain nicotine, which can be extracted and used as an insecticide. The dried leaves can also be used; they remain effective for 6 months after drying. The juice of the leaves can be rubbed on the body as an insect repellent. The leaves can be dried and chewed as an intoxicant. The dried leaves are also used as snuff or are smoked. This is the main species that is used to make cigarettes, cigars, and other smokable tobacco preparations. A drying oil is obtained from the seed.

Curing and aging

After tobacco is harvested, it is cured (dried), and then aged to improve its flavor. There are four common methods of curing tobacco: air curing, fire curing, flue curing, and sun curing. The curing method used depends on the type of tobacco and its intended use. Air-cured tobacco is sheltered from wind and sun in a well-ventilated barn, where it air dries for six to eight weeks. Air-cured tobacco is low in sugar, which gives the tobacco smoke a light, sweet flavor, and high in nicotine. Cigar and burley tobaccos are air cured. In fire curing, smoke from a low-burning fire on the barn floor permeates the leaves. This gives the leaves a distinctive smoky aroma and flavor. Fire curing takes three to ten weeks and produces a tobacco low in sugar and high in nicotine. Pipe tobacco, chewing tobacco, and snuff are fire cured. Flue-cured tobacco is kept in an enclosed barn heated by flues (pipes) of hot air, but the tobacco is not directly exposed to smoke. This method produces cigarette tobacco that is high in sugar and has medium to high levels of nicotine. It is the fastest method of curing, requiring about a week. Virginia tobacco that has been flue cured is also called bright tobacco, because flue curing turns its leaves gold, orange, or yellow. Sun-cured tobacco dries uncovered in the sun. This method is used in Greece, Turkey, and other Mediterranean countries to produce oriental tobacco. Sun-cured tobacco is low in sugar and nicotine and is used in cigarettes. Once the tobacco is cured, workers tie it into small bundles of about 20 leaves, called hands, or use a machine to make large blocks, called bales. The hands or bales are carefully aged for one to three years to improve flavor and reduce bitterness.

See also

Gallery

References

  1. ↑ Ren, Nan; Timko, Michael P. (2001). "AFLP analysis of genetic polymorphism and evolutionary relationships among cultivated and wild Nicotiana species". Genome 44 (4): 559–71. doi:10.1139/gen-44-4-559. PMID 11550889.
  2. ↑ Wennig, Robert (2009). "Back to the roots of modern analytical toxicology: Jean Servais Stas and the Bocarmé murder case". Drug Testing and Analysis 1 (4): 153–5. doi:10.1002/dta.32. PMID 20355192.
  3. ↑ Groark, Kevin P. (2010). "The Angel in the Gourd: Ritual, Therapeutic, and Protective Uses of Tobacco (Nicotiana tabacum) Among the Tzeltal and Tzotzil Maya of Chiapas, Mexico". Journal of Ethnobiology 30 (1): 5–30. doi:10.2993/0278-0771-30.1.5.
  4. ↑ Otsu, C. T.; Dasilva, I; De Molfetta, JB; Da Silva, LR; De Almeida-Engler, J; Engler, G; Torraca, PC; Goldman, GH; Goldman, MH (2004). "NtWBC1, an ABC transporter gene specifically expressed in tobacco reproductive organs". Journal of Experimental Botany 55 (403): 1643–54. doi:10.1093/jxb/erh195. PMID 15258165.

Further reading

External links

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