Peach

Peach
Autumn Red Peaches, cross section
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Rosales
Family:	Rosaceae
Genus:	Prunus
Subgenus:	Amygdalus
Species:	P. persica
Binomial name
Prunus persica (L.) Batsch

The peach tree (Prunus persica) is a species of Prunus native to China that bears an edible juicy fruit called a peach. It is a deciduous tree growing to 4–10 m tall, belonging to the subfamily Prunoideae of the family Rosaceae. It is classified with the almond in the subgenus Amygdalus within the genus Prunus, distinguished from the other subgenera by the corrugated seed shell.

The leaves are lanceolate, 7–16 cm long (3–6 in), 2–3 cm broad, pinnately veined. The flowers are produced in early spring before the leaves; they are solitary or paired, 2.5–3 cm diameter, pink, with five petals. The fruit has yellow or whitish flesh, a delicate aroma, and a skin that is either velvety (peaches) or smooth (nectarines) in different cultivars. The flesh is very delicate and easily bruised in some cultivars, but is fairly firm in some commercial varieties, especially when green. The single, large seed is red-brown, oval shaped, approximately 1.3–2 cm long, and is surrounded by a wood-like husk. Peaches, along with cherries, plums and apricots, are stone fruits (drupes).

The scientific name persica, along with the word "peach" itself and its cognates in many European languages, derives from an early European belief that peaches were native to Persia (now Iran). The modern botanical consensus is that they originate in China, and were introduced to Persia and the Mediterranean region along the Silk Road before Christian times.^[1] Cultivated peaches are divided into clingstones and freestones, depending on whether the flesh sticks to the stone or not; both can have either white or yellow flesh. Peaches with white flesh typically are very sweet with little acidity, while yellow-fleshed peaches typically have an acidic tang coupled with sweetness, though this also varies greatly. Both colours often have some red on their skin. Low-acid white-fleshed peaches are the most popular kinds in China, Japan, and neighbouring Asian countries, while Europeans and North Americans have historically favoured the acidic, yellow-fleshed kinds.

History

Although its botanical name Prunus persica suggests the peach is native to Persia, peaches actually originated in China where they have been cultivated since the early days of Chinese culture. Peaches were mentioned in Chinese writings as far back as the 10th century BC and were a favoured fruit of kings and emperors. Recently, the history of cultivation of peaches in China has been extensively reviewed citing numerous original manuscripts dating back to 1100 B.C. ^[2]

Its English name derives originally from the Latin Prunus persica, then persica, then pessica, then pesca, then the French pêche, then peach in Middle English.

The peach was brought to India and Western Asia in ancient times.^[3] Alexander the Great introduced the fruit into Europe after he conquered the Persians.^[3] Then it was brought to America by Spanish explorers in the 16th century and eventually made it to England and France in the 17th century, where it was a prized, albeit rare, treat.

The horticulturist George Minifie supposedly brought the first peaches from England to its North American colonies in the early 17th century, planting them at his Estate of Buckland in Virginia.^[4]

Various American Indian tribes are credited with spreading the peach tree across the United States, taking seeds along with them and planting as they roved the country.

Although Thomas Jefferson had peach trees at Monticello, United States farmers did not begin commercial production until the 19th century in Maryland, Delaware, Georgia and finally Virginia. California today grows 65% of peaches grown for commercial production in the United States,^[5] but the northern states of Colorado, Michigan, and Washington also grow a significant amount. Italy, China, India and Greece are major producers of peaches outside of the United States.

In 2010, a team of researchers at Clemson University, USA, announced they had sequenced the peach tree genome (doubled haploid Lovell).^[6][7]

Cultivation

Worldwide peach and nectarine output in 2005

Peach plants grow very well in a fairly limited range, since they have a chilling requirement that tropical areas cannot satisfy, and they are not very cold-hardy. The trees themselves can usually tolerate temperatures to around −26 °C to −30 °C, although the following season's flower buds are usually killed at these temperatures, leading to no crop that summer. Flower bud kill begins to occur between −15 °C and −25 °C depending on the cultivar (some are more cold-tolerant than others) and the timing of the cold, with the buds becoming less cold tolerant in late winter.^[8] Certain cultivars are more tender and others can tolerate a few degrees colder. In addition, a lot of summer heat is required to mature the crop, with mean temperatures of the hottest month between 20 °C and 30 °C. Another problematic issue in many peach-growing areas is spring frost. The trees tend to flower fairly early in spring. The blooms often can be damaged or killed by freezes; typically, if temperatures drop below about −4 °C, most flowers will be killed. However, if the flowers are not fully open, they can tolerate a couple of degrees colder.

Important historical peach-producing areas are China, Iran, France, and the Mediterranean countries like Italy, Spain and Greece. More recently, the United States (where the three largest-producing states are California, South Carolina,^[9] and Georgia^[10]), Canada (British Columbia), and Australia (the Riverland region) have also become important; peach growing in the Niagara Peninsula of Ontario, Canada, was formerly intensive but slowed substantially in 2008 when the last fruit cannery in Canada was closed by the proprietors^[11]. Oceanic climate areas like the Pacific Northwest and coastline of North Western Europe are generally not satisfactory for peach-growing due to inadequate summer heat, though they are sometimes grown trained against south-facing walls to catch extra heat from the sun. Trees grown in a sheltered and south-facing position in the southeast of England are capable of producing both flowers and a large crop of fruit. In Vietnam, the most famous variety of peach fruit product is grown in Mẫu Sơn commune, Lộc Bình district, Lạng Sơn province.

For home gardeners, semi-dwarf (3 to 4 m) and dwarf (2 to 3 m) varieties have been developed by grafting desirable cultivars onto dwarfing rootstock. Fruit size is not affected. Another mutation is flowering peaches, selected for ornamental display rather than fruit production.

Depending on climate and cultivar, peach harvest can occur from late May into August; harvest from each tree lasts about a week.

Nectarines

White nectarines, whole and cut open

The nectarine is a cultivar group of peach that has a smooth skin. Though fuzzy peaches and nectarines are regarded commercially as different fruits, with nectarines often erroneously believed to be a crossbreed between peaches and plums, or a "peach with a plum skin", they belong to the same species as peaches. Several genetic studies have concluded in fact that nectarines are created due to a recessive gene, whereas a fuzzy peach skin is dominant.^[12] Nectarines have arisen many times from peach trees, often as bud sports.

As with peaches, nectarines can be white or yellow, and clingstone or freestone. On average, nectarines are slightly smaller and sweeter than peaches, but with much overlap.^[12] The lack of skin fuzz can make nectarine skins appear more reddish than those of peaches, contributing to the fruit's plum-like appearance. The lack of down on nectarines' skin also means their skin is more easily bruised than peaches.

The history of the nectarine is unclear; the first recorded mention in English is from 1616,^[13] but they had probably been grown much earlier within the native range of the peach in central and eastern Asia. Nectarines were introduced into the United States by David Fairchild of the Department of Agriculture in 1906.^[14]

Diseases

The trees are prone to a disease called leaf curl, which usually does not directly affect the fruit but does reduce the crop yield by partially defoliating the tree. The fruit is very susceptible to brown rot, or a dark reddish spot.

Planting

The developmental sequence of a nectarine over a 7 ¹⁄₂-month period, from bud formation in early winter to fruit ripening in midsummer (see image page for further information)

Most peach trees sold by nurseries are named cultivars budded or grafted onto a suitable rootstock. It is also possible to grow a tree from either a peach or nectarine seed, but the fruit quality of the resulting tree will be very unpredictable.

Peaches should be located in full sun, and with good air flow. This allows cold air to flow away on frosty nights and keeps the area cool in summer. Peaches are best planted in early winter, as this allows time for the roots to establish and to sustain the new spring growth. When planting in rows, plant north–south.

For optimum growth, peach trees require a constant supply of water. This should be increased shortly before the harvest. The best tasting fruit is produced when the peach is watered throughout the season. Drip irrigation is ideal, with at least one dripper per tree. Although it is better to use multiple drippers around the tree, this is not necessary. A quarter of the root being watered is sufficient.

Peaches have a high nutrient requirement, needing more nitrogen than most other fruit trees. An NPK fertilizer can be applied regularly, and an additional mulch of poultry manure in autumn soon after the harvest will benefit the tree. If the leaves of the peach are yellow or small, the tree needs more nitrogen. Blood meal and bone meal, 3–5 kg per mature tree, or calcium ammonium nitrate, 0.5–1 kg, are suitable fertilizers. This also applies if the tree is putting forth little growth.

If the full amount of peaches is left, they will be under-sized and lacking in sugar and flavour. In dry conditions, extra watering is important. The fruit should be thinned when they have reached 2 cm in diameter, usually about two months after flowering. Fresh fruit are best consumed on the day of picking, and do not keep well. They are best eaten when the fruit is slightly soft, having aroma, and heated by the sun.

Storage

Peaches should be stored at room temperature and refrigeration should be avoided as this can lessen the taste of the peach. Peaches do not ripen after being picked from the tree, so storing for ripening is not necessary.^[15]

Asian tradition

The Chinese flat peach, also called Paraguaya (Paraguayan)

Peaches are known in China, Japan, Korea, Laos, and Vietnam not only as a popular fruit but for the many folk tales and traditions associated with it.

In China, the peach was said to be consumed by the immortals due to its mystic virtue of conferring longevity on all who ate them. The divinity Yu Huang, also called the Jade Emperor, and his mother Xi Wangmu, also known as Queen Mother of the West, ensured the gods' everlasting existence by feeding them the peaches of immortality. The immortals residing in the palace of Xi Wangmu were said to celebrate an extravagant banquet called the Pantao Hui or "The Feast of Peaches". The immortals waited six thousand years before gathering for this magnificent feast; the peach tree put forth leaves once every thousand years and it required another three thousand years for the fruit to ripen. Ivory statues depicting Xi Wangmu's attendants often held three peaches.

A Chinese Song Dynasty painting of a bird and peach blossom, by Emperor Huizong of Song, 11th century

The peach often plays an important part in Chinese tradition and is symbolic of long life. One example is in the peach-gathering story of Zhang Daoling, who some say is the true founder of Taoism. Elder Zhang Guo, one of the Chinese Eight Immortals, is often depicted carrying a Peach of Immortality. The peach blossoms are highly prized in Chinese culture.

It was in an orchard of flowering peach trees that Liu Bei, Guan Yu, and Zhang Fei took an oath of brotherhood in the opening chapter of the classic Chinese novel Romance of the Three Kingdoms.

Momotaro, one of Japan's most noble and semi-historical heroes, was born from within an enormous peach floating down a stream. Momotaro or "Peach Boy" went on to fight evil oni and face many adventures. Specialty U.S. tea company Teavana carries an artisan blooming white tea called Peach Momotaro, in regards to the Japanese mythological character, which is peach scented. http://www.teavana.com/The-Teas/Blooming-Teas/Peach-Momotaro-Artisan-Tea.axd

In Korea, peaches have been cultivated from ancient times. According to Samguk Sagi, peach trees were planted during the Three Kingdoms of Korea period, and Sallim gyeongje also mentions cultivation skills of peach trees. Peach is seen as the fruit of happiness, riches, honours and longevity. It is one of the ten immortal plants and animals, so peach appears in many minhwa (folk painting). It is believed that peach and peach trees chase away spirits, so peach is not placed on the table for jesa (ancestor veneration) unlike other fruits.^[16][17]

A Vietnamese mythic history states that, in the spring of 1789, after marching to Ngọc Hồi and then winning a great victory against invaders from the Qing Dynasty of China, the King Quang Trung ordered a messenger to gallop to Phú Xuân citadel (Huế nowadays) and deliver a flowering peach branch to the Princess Ngọc Hân. This took place on the fifth day of the first lunar month, two days before the predicted end of the battle. The branch of peach flowers that was sent from the North to the Centre of Vietnam was not only a message of victory from the King to his wife, but also the start of a new spring of peace and happiness for all the Vietnamese people. In addition to that, since the land of Nhật Tân had freely given that very branch of peach flowers to the King, it became the loyal garden of his dynasty.

A peach tree is also the context in which Kim Trọng and Thuý Kiều fell in love in The Tale of Kieu. And in Vietnam, the blossoming peach flower is the signal of spring. Finally, peach bonsai trees are used as decoration during Vietnamese New Year (Tết) in Northern Vietnam.

Nutrition and health

A medium peach (75 g), has 30 Cal, 7 g of carbohydrate (6 g sugars and 1 g fibre), 1 g of protein, 140 mg of potassium, and 8% of the daily value (DV) for vitamin C.^[18]

As with many other members of the rose family, peach seeds contain cyanogenic glycosides, including amygdalin (note the subgenus designation: Amygdalus). These substances are capable of decomposing into a sugar molecule and hydrogen cyanide gas. While peach seeds are not the most toxic within the rose family, that dubious honour going to the bitter almond, large doses of these chemicals from any source are hazardous to human health.

Peach allergy or intolerance is a relatively common form of hypersensitivity to proteins contained in peaches and related fruit (almonds). Symptoms range from local symptoms (e.g. oral allergy syndrome, contact urticaria) to systemic symptoms including anaphylaxis (e.g. urticaria, angioedema, gastrointestinal and respiratory symptoms).^[19] Adverse reactions are related to the "freshness" of the fruit: peeled or canned fruit may be tolerated.

Gallery

A peach tree in blossom	Developing Fruit	Peach flower	Flavorcrest peaches
Peach (cultivar 'Berry') – watercolour 1895	Harvested peaches	White peach and cross section	Peach Melba

References

External links

• Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.
• National Center for Home Food Preservation—Freezing Peaches
• Prunus persica images at bioimages.vanderbilt.edu
• Everything About Peaches