ONION

ONION

The onion, or Allium cepa by its botanical name, has been known since mankind's' most remote antiquity. In the past, it had a strong reputation for its nutritional and therapeutic properties. It was considered sacred in Egypt, China, Oriental Asia, and Asia Minor. It seems that onions were an essential element to the nutrition of the laborers who built the pyramids of Egypt. An important ingredient in Etruscan and in Roman cuisine, the onion was fundamental during the Middle Ages. Today, this vegetable can be found in almost every kitchen in the world. Introduced to America by Christopher Columbus, it is also a part of American fast food, notably as onion rings (fried onion). In France, it is famous for having been made into a soup and in our country it is an essential ingredient in sautéed, the base of a great number of dishes.
From a nutrional point of view, the onion has a consistent nutritive value, thanks to the presence of mineral salts such as sodium, iron, potassium, sulfur, iodide, and silicon, as well as vitamins (particularly vitamins C, A, E, and complex B). Pharmacology confers it a moderate detoxifying value for the kidneys, a mild action in the prevention of atherosclerosis, and it has a small part to play as an antibacterial. In more sensitive people, it slows the digestive process and increases the acidic level of the stomach. The onion also has lachrymose properties due to the presence of sulfoxides. These, at the moment in which the bulbs are cut, produce a volatile substance that generates sulfuric acid upon contact with the eyes and, even if very bland, causes irritation and tearing.

CULTIVATION

There are two types of onions: the one for late consumption and the one for fresh consumption. The first, after the harvest and a drying period, can be stored and used over time. One plants it in spring and harvests it in summer after a period of cultivation that from transplanting to harvest can last from 60 to 90 days, depending on the variety. A good crop can give 2 to 5 kg / sqm of onions but for this sort of production, one should provide an adequate supply of fertilizers. The key issue is the provision of organic fertilizers in amounts of 2-3 kg/sqm, to which one must add 30 to 40 gr/sqm of potassium sulphate and an equal amount of mineral superphosphate, or else, 60 grams of a complex such as 11/22/16. On top of the soil, you can intervene with two or three spaced interventions with calcium nitrate at a rate of 10 g / sqm at a time. Given the scarse coverage of the land, there is the danger of a strong growth of weeds, so one should hoe frequently or if not, transplant on mulched soil (covered with black plastic). The distance to transplant onions of medium size may be 15-20 cm between rows and 15 cm on the row, corresponding to an average of about 30 to 40 plants per square meter. Harvesting is done when the leaves begin to dry; after extraction from the soil, it would be good that they be left some days to dry in the sun before storing them.

ADVERSITIES

Among the major fungal parasites that attack the onion and its aerial apparatus in particular, are downy mildew (P. schleideni) and rust (Puccinia spp.). The first causes necrotic spots and the second, yellowish or reddish speckles. Both can be controlled with copper-based sprays. Fusarium (Fusarium oxysporum f.sp. cepae) and gray mold (Botrytis allii) typically affect the bulb and the roots; both fungi propagate in moist, infected soil. To contain them, it is good to avoid planting onions where there were already bulbs the year before and to keep the soil free from stagnant moisture. Among the insects, the fly (Delia antiqua), whose larva pierces the plant's tissues between the collar and the bulb, is particularly harmful since the insect hibernates in the soil and flickers with the first warmth of spring; postponing the transplants helps avoid at least the first attacks.