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Potato
Scientific classification
Kingdom: Plantae (unranked): Angiosperms (unranked): Eudicots (unranked): Asterids Order: Solanales Family: Solanaceae Genus: Solanum Species: S. tuberosum
Binomial name
Solanum tuberosum L.

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family (also known as the nightshades). The word potato may refer to the plant itself as well. In the region of the Andes, there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food crop, following rice, wheat, and maize.^[1]

Wild potato species occur from the United States to Uruguay and Peru.^[2] Genetic testing of the wide variety of cultivars and wild species suggest that the potato has a single origin in the area of southern Peru,^[3] from a species in the Solanum brevicaule complex. Although Peru is essentially the birthplace of the potato, today over 99% of all cultivated potatoes worldwide are descendants of a subspecies indigenous to south-central Chile.^[4] Based on historical records, local agriculturalists, and DNA analyses, the most widely cultivated variety worldwide, Solanum tuberosum ssp. tuberosum, is believed to be indigenous to the Chiloé Archipelago where it was cultivated as long as 10,000 years ago.^[5][6]

The potato was introduced to Europe in 1536,^[7] and subsequently by European mariners to territories and ports throughout the world.^[8] Thousands of varieties persist in the Andes, where over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household.^[9] Once established in Europe, the potato soon became an important food staple and field crop. But lack of genetic diversity, due to the fact that very few varieties were initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine. The potato was the first vegetable inherited by the early Australians, the Aborigines. Australia now leads the largest potato crops seen throughout the world.^[7]

The annual diet of an average global citizen in the first decade of the twenty-first century would include about 33 kilograms (or 73 lbs.) of potato. However, the local importance of potato is extremely variable and rapidly changing. The potato remains an essential crop in Europe (especially eastern and central Europe), where per capita production is still the highest in the world, but the most rapid expansion of potato over the past few decades has occurred in southern and eastern Asia. China is now the world's largest potato producing country, and nearly a third of the world's potatoes are harvested in China and India.^[10] More generally, the geographic shift of potato production has been away from wealthier countries toward lower-income areas of the world, although the degree of this trend is ambiguous.^[11]

 Etymology

The English word potato comes from Spanish patata (the name used in Spain). The Spanish Royal Academy says the Spanish word is a compound of the Taino batata (sweet potato) and the Quechua papa (potato).^[12] This probably indicates that originally, the potato was regarded as a type of sweet potato rather than the other way around, despite the fact that there is actually no close relationship between the two plants at all. Potatoes are occasionally referred to as "Irish potatoes" in the English speaking world, to distinguish them from sweet potatoes. In certain dialects of English, particularly in North America, the words taters, potaters, and tatoes are sometimes used. In the UK the words spuds, taties and tatties are often used. In some dialects of English spoken in Ireland, potatoes are called praties, which, presumably, comes from prátaí, the plural form of the Irish word for potato, práta. As well, the Hebrew word for sweet potato, is batata (בטטה).

Romanian cartof, Ukrainian kartóplja (картопля) , Bulgarian kartof (картоф), Russian kartofel (kарҭофель), German Kartoffel, Danish kartoffel, Icelandic kartafla (or jarðepli, see below), Latvian kartupelis, and Estonian kartul (as well as many other similar names in various languages) all derive from the archaic Italian word tartufoli, which was given to potato because of its similarity to truffles (Italian: tartufo). However, the current Italian term for the potato is patata.

The French refer to the potato as pomme de terre. which literally means "earth apple". Other European translations include aardappel in Dutch, jarðepli in Icelandic (or kartafla, see above), Erdapfel in Austrian German, sib zamini (Persian: سیب‌زمینی) in Persian. It is called ziemniaki (or kartofle in some regions) in Polish, and zemiak in Slovak, both simply from the word for "ground". Also, this usage is found in Hebrew as tapuach adama (Hebrew: תפוח אדמה‎; lit. "earth apple") (often written just as תפו"א).

An analogous name in Finnish is peruna, which comes from the old Swedish jordpäron "earth pear".

In Marathi and Gujarati, the potato is called bataka or batata, while in most other South Asian languages, (e.g. Hindi, Nepali, Bengali) it is called Alu (आलू). In Telugu, it is called "Ulla gadda" (ఉల్ల గడ్డ) or "Bangaala dumpa" (బంగాల దుంప).

Different names for the potato developed in China's various regions. The most widely used names in Standard Mandarin are "horse-bell yam" (simplified Chinese: 马铃薯; pinyin: mǎlíngshǔ), "earth bean" (simplified Chinese: 土豆; pinyin: tǔdòu), and "foreign taro" (simplified Chinese: 洋芋; pinyin: yángyù).

The Malay/Indonesian name is kentang.

 Description

Flowers of a potato plant

Potato plants are herbaceous perennials that grow about 60 cm high, depending on variety, the culms dying back after flowering. They bear white, pink, red, blue or purple flowers with yellow stamens resembling those of other Solanaceous species such as tomato and aubergine. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins.^[13] Potatoes are cross-pollinated mostly by insects, including bumblebees that carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.^[14]

Potato plants

After potato plants flower, some varieties will produce small green fruits that resemble green cherry tomatoes, each containing up to 300 true seeds. Potato fruit contains large amounts of the toxic alkaloid solanine, and is therefore unsuitable for consumption.

All new potato varieties are grown from seeds, also called "true seed" or "botanical seed" to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds will separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit will float). Any potato variety can also be propagated vegetatively by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce seeds at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".

Genetics

The potatoes cultivated in the Andes are not all the same species. However, the major species grown worldwide is Solanum tuberosum (a tetraploid with 48 chromosomes). Modern varieties of this species are the most widely cultivated worldwide. There are also four diploid species (with 24 chromosomes): Solanum stenotomum, Solanum phureja, Solanum goniocalyx and Solanum ajanhuiri. There are two triploid species (with 36 chromosomes): Solanum chaucha and Solanum juzepczukii. There is one pentaploid cultivated species (with 60 chromosomes): Solanum curtilobum.

There are two major subspecies of Solanum tuberosum: andigena, or Andean; and tuberosum, or Chilean.^[15] The Andean potato is adapted to the short-day conditions prevalent in the mountainous equatorial and tropical regions where it originated. The Chilean potato is adapted to the long-day conditions prevalent in the higher latitude region of southern Chile, especially on Chiloé Archipelago where it is thought to have originated.^[16] Genetic testing done in 2005 shows that both species derive from a single origin in the area of southern Peru.^[17]

There are about five thousand potato varieties world wide. Three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile and Colombia. They belong to eight or nine species, depending on the taxonomic school. Apart from the five thousand cultivated varieties, there are about 200 wild species and subspecies, many of which can be cross-bred with cultivated varieties, which has been done repeatedly to transfer resistances to certain pests and diseases from the gene pool of wild species to the gene pool of cultivated potato species. Genetically modified varieties have met public resistance in the United States and in the European Union.^[18][19]

Most modern potatoes grown in North America arrived through European settlement and not independently from the South American sources. However, at least one wild potato species, Solanum fendleri, is found as far north as Texas and used in breeding for resistance to a nematode species attacking cultivated potatoes. A secondary center of genetic variability of the potato is Mexico, where important wild species are found that have been used extensively in modern breeding, such as the hexaploid Solanum demissum, as a source of resistance to the devastating late blight disease. Another plant native to this region, Solanum bulbocastanum, a close relative of the potato, has been used to genetically engineer the potato to effectively resist potato blight.^[20]

The International Potato Center, based in Lima, Peru, holds an ISO-accredited collection of potato germplasm.^[21]

Role in world food supply

Although it was initially feared to be poisonous, the potato became an important staple crop in northern Europe. Famines in the early 1770s contributed to its acceptance, as did government policies in several European countries and climate change during the Little Ice Age, when traditional crops in this region did not produce as reliably as before.^[22][23] At times when and where most other crops would fail, potatoes could still typically be relied upon to contribute adequately to food supplies during the colder years. Its yield of Calories per acre (about 9.2 million) is higher than that of maize (7.5 million), rice (7.4 million), wheat (3 million), or soybean (2.8 million).^[24] The potato was not popular in France during this time, and it is believed that some of the infamous famines could have been lessened if French farmers had adopted it. Today, the potato forms an important part of the traditional cuisines of most of Europe. Belarus has the highest consumption of potato per capita with each Belorussian consuming 338 kg in 2005.^[25][26]

The potato was introduced in the Philippines during the late 16th century, and to Java and China during the 17th century. It was well-established as a crop in India by the late 18th century and in Africa by the mid-20th century.^[23]

The United Nations FAO reports that the world production of potatoes in 2006 was 315 million tonnes. The largest producer, China, accounted for one quarter of the global output, followed by Russia and India.

In 2008, several international organizations began to give more emphasis to the potato as a key part of world food production, due to several developing economic problems. They cited the potato's potential for a beneficial role in world food production, owing to its status as a cheap and plentiful crop which can be raised in a wide variety of climates and locales.^[27] Due to perishability, only about 5% of the world's potato crop is traded internationally; its minimal presence in world financial markets contributed to its stable pricing during the 2007–2008 world food price crisis.^[28][29]

In recognition of this importance, the United Nations officially declared the year 2008 as the International Year of the Potato^[30] in order to "increase awareness of the importance of the potato as a food in developing nations" and calling the crop a "hidden treasure".^[31] This follows the International Rice Year in 2004.

Nutrition

Potatoes contain vitamins and minerals that have been identified as vital to human nutrition. Humans can subsist healthily on a diet of potatoes and milk; the latter supplies Vitamin A and Vitamin D.^[23] A medium potato (150g/5.3 oz) with the skin provides 27 mg of vitamin C (45% of the Daily Value (DV)), 620 mg of potassium (18% of DV), 0.2 mg vitamin B6 (10% of DV) and trace amounts of thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. Moreover, the fiber content of a potato with skin (2 grams) equals that of many whole grain breads, pastas, and cereals. Potatoes also contain an assortment of phytochemicals, such as carotenoids and polyphenols.

Nutritionally, potatoes are best known for their carbohydrate content (approximately 26 grams in a medium potato). The predominant form of this carbohydrate is starch. A small but significant portion of this starch is resistant to digestion by enzymes in the stomach and small intestine, and so reaches the large intestine essentially intact. This resistant starch is considered to have similar physiological effects and health benefits as fiber: it provides bulk, offers protection against colon cancer, improves glucose tolerance and insulin sensitivity, lowers plasma cholesterol and triglyceride concentrations, increases satiety, and possibly even reduces fat storage (Cummings et al. 1996; Hylla et al. 1998; Raban et al. 1994). The amount of resistant starch in potatoes depends much on preparation methods. Cooking and then cooling potatoes significantly increased resistant starch. For example, cooked potato starch contains about 7% resistant starch, which increases to ab