Sunday, July 17, 2016

Onions. How To Grow, When To Harvest, How To Harvest, Storage. The life ...



The onion (Allium cepa L., from Latin cepa "onion"), also known as the bulb onion or common onion, is a vegetable and is the most widely cultivated species of the genus Allium.

This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (Allium fistulosum), the tree onion (A. ×proliferum), and the Canada onion (Allium canadense).

The name "wild onion" is applied to a number of Allium species, but A. cepa is exclusively known from cultivation.

Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions.[2]

The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested in its first growing season.

The onion plant has a fan of hollow, bluish-green leaves and the bulb at the base of the plant begins to swell when a certain day-length is reached.

In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become dry and brittle.

The crop is harvested and dried and the onions are ready for use or storage.

The crop is prone to attack by a number of pests and diseases, particularly the onion fly, the onion eelworm, and various fungi cause rotting.

Some varieties of A. cepa, such as shallots and potato onions, produce multiple bulbs.

Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savoury dish, but can also be eaten raw or used to make pickles or chutneys.

They are pungent when chopped and contain certain chemical substances which irritate the eyes.

Onion

Mixed onions.jpg
Scientific classification e
Kingdom: Plantae
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Amaryllidaceae
Subfamily: Allioideae
Genus: Allium
Species: A. cepa
Binomial name
Allium cepa
L.
Synonyms[1]

 
Roots, leaves and developing bulb
 
Umbel of onion flowers


Taxonomy and etymology

The onion plant (Allium cepa), also known as the bulb onion[3] or common onion,[4] is the most widely cultivated species of the genus Allium.[5][6]

It was first officially described by Carl Linnaeus in his 1753 work Species Plantarum.[7]

A number of synonyms have appeared in its taxonomic history:
  • Allium cepa var. aggregatum – G. Don
  • Allium cepa var. bulbiferum – Regel
  • Allium cepa var. cepa – Linnaeus
  • Allium cepa var. multiplicans – L.H. Bailey
  • Allium cepa var. proliferum – (Moench) Regel
  • Allium cepa var. solaninum – Alef
  • Allium cepa var. viviparum – (Metz) Mansf.[8][9]
A. cepa is known exclusively from cultivation,[10] but related wild species occur in Central Asia. The most closely related species include A. vavilovii (Popov & Vved.) and A. asarense (R.M. Fritsch & Matin) from Iran.[11]

However, Zohary and Hopf state that "there are doubts whether the A. vavilovii collections tested represent genuine wild material or only feral derivatives of the crop."[12]

The vast majority of cultivars of A. cepa belong to the "common onion group" (A. cepa var. cepa) and are usually referred to simply as "onions". T

he Aggregatum group of cultivars (A. cepa var. aggregatum) includes both shallots and potato onions.[13]

The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (A. fistulosum), Egyptian onion (A. ×proliferum), and Canada onion (A. canadense).[4]

Cepa is commonly accepted as Latin for "onion" and has an affinity with Ancient Greek: κάπια (kápia), Albanian: qepë, Aromanian: tseapã, Catalan: ceba, English: chive, Occitan: ceba, Old French: cive, and Romanian: ceapă.


Description


The onion plant has been grown and selectively bred in cultivation for at least 7,000 years. It is a biennial plant, but is usually grown as an annual.

Modern varieties typically grow to a height of 15 to 45 cm (6 to 18 in).

The leaves are yellowish-green and grow alternately in a flattened, fan-shaped swathe.

They are fleshy, hollow, and cylindrical, with one flattened side.

They are at their broadest about a quarter of the way up beyond which they taper towards a blunt tip.

The base of each leaf is a flattened, usually white sheath that grows out of a basal disc.

From the underside of the disc, a bundle of fibrous roots extends for a short way into the soil.

As the onion matures, food reserves begin to accumulate in the leaf bases and the bulb of the onion swells.[14]

In the autumn, the leaves die back and the outer scales of the bulb become dry and brittle, and this is when the crop is normally harvested.

If left in the soil over winter, the growing point in the middle of the bulb begins to develop in the spring.

New leaves appear and a long, stout, hollow stem expands, topped by a bract protecting a developing inflorescence.


Historical use


The inflorescence takes the form of a globular umbel of white flowers with parts in sixes.

The seeds are glossy black and triangular in cross section.[14]

Bulbs from the onion family are thought to have been used as a food source for millennia.

In Bronze Age settlements, traces of onion remains were found alongside date stones and fig remains that date back to 5000 BC.[15]

However, it is not clear if these were cultivated onions.

Archaeological and literary evidence such as the Book of Numbers 11:5 suggests that onions were probably being cultivated around 2000 years later in ancient Egypt, at the same time that leeks and garlic were cultivated.

Workers who built the Egyptian pyramids may have been fed radishes and onions.[15]

The onion is easily propagated, transported, and stored.

The ancient Egyptians revered the onion bulb, viewing its spherical shape and concentric rings as symbols of eternal life.[16]

Onions were even used in Egyptian burials, as evidenced by onion traces being found in the eye sockets of Ramesses IV.[17]

In ancient Greece, athletes ate large quantities of onion because it was believed to lighten the balance of the blood.[16]

Roman gladiators were rubbed down with onions to firm up their muscles.[16]

In the Middle Ages, onions were such an important food that people would pay their rent with onions, and even give them as gifts.[16]

Doctors were known to prescribe onions to facilitate bowel movements and erections, and to relieve headaches, coughs, snakebite, and hair loss.[16]

Onions were taken by the first European settlers to North America, where the Native Americans were already using wild onions in a number of ways, eating them raw or cooked in a variety of foods.

They also used them to make into syrups, to form poultices, and in the preparation of dyes.

According to diaries kept by the colonists, bulb onions were one of the first things planted by the Pilgrim fathers when they cleared the land for cropping.[16]

Onions were also prescribed by doctors in the early 16th century to help with infertility in women.

They were similarly used to raise fertility levels in dogs, cats, and cattle, but this was an error, as recent research has shown that onions are toxic to dogs, cats, guinea pigs, and many other animals.[18][19][20]


 
Sautéing onions

 
Large-scale cultivation


Check Out The Wikipedia Page for the rest of the story on Onions



Source: Wikipedia.org https://en.wikipedia.org/wiki/Onion





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