Shallots are cool season, herbaceous, biennial plants grown for their tender greens and dried bulbs. Young, tender leaves of shallots are often marketed as ‘green onions’ and/or ‘scallions’. For leafy vegetable purposes, they are grown as annuals. Bulbs of shallots are also known as ‘small onions’ as their bulbs look like small-sized common onions.
Taxonomy and Origin: Shallots are bulb vegetables belonging to the bulb-forming, onion family (Amaryllidaceae). Other members of onion family include common onions, garlic, leek, etc. Scientific name of common shallot is Allium cepa var. aggregatum. Persian shallot is Allium stipitatum and French gray shallot or griselle is Allium oschaninii. Shallots are believed to be originated in Central or Southwest Asia.
Plant Description: Shallots produce a cluster of bulbs from a single planted bulb. They are tender, herbaceous plants that form a cluster of small bulbs beneath the ground at the time of maturity. They have long, hollow, tubular green leaves similar to those of the other members of the onion family. Leaves grow directly from the bulb.
Bulb Description: In shallots, small bulbs are formed in clusters with each individual head composed of multiple cloves. Skin colour of the bulb varies from golden brown to red to pale pink. Flesh of bulb is creamish to off-white in colour.
Food Uses of Shallot Bulbs: Fresh, raw shallots are used in making chutneys and salads. Shallots may be pickled alone or with other vegetables. Finely-sliced, deep-fried shallots are used as a condiment in many Asian food preparations. Shallots are an essential ingredient in many South Indian food preparations.
Nutrition in Shallots: According to USDA nutrient database, the nutrient composition of fresh, raw shallots is:
Protein -2.5 g, Fiber -3.2 g, Calcium -37 mg, Iron -1.2 mg, Potassium -334 mg, Zinc -0.4 mg, Vitamin C -8 mg, Thiamin -0.06 mg, Riboflavin -0.02 mg, Niacin -0.2 mg, Vitamin B-6 -0.345 mg, Folate -34 ug, Vitamin A -4 IU, Vitamin E -0.04 mg and Vitamin K -0.8 ug
Growing Shallots: Growing practices for shallots are similar to those of common onions. A detailed account of growing practices for shallots is given below:
Climate and Soil: Shallot plants prefer sunny locations and mild climates. The plants thrive best in well-drained, deep and dry soils which are rich in organic matter.
Propagation: Shallots are propagated by seed bulbs. Seed bulbs are selected from healthy ‘mother plants’ which are devoid of diseases and insect-pests. While planting, the top portion of the seed bulbs should be kept a little above the ground level.
Planting: Bulbs are planted in well-prepared and well-manured site/land. At the time of land preparation, top soil is mixed with organic manures such as farm yard manure and compost to enhance the soil fertility. Nitrogenous fertilizers may also be mixed with the soil to encourage vegetative growth of the plants. After land preparation, the site is left undisturbed for a certain period of time before planting. In other words, seed bulbs should not be planted in freshly manured land.
Bulbs are planted in late summer or fall. Soon after planting the bulbs, a light irrigation is given. As the plants start growing, soil around the plants are pushed away from the plant base in order to blanch the lower portion of the plant. This is an important practice to be followed while growing shallots.
Manuring and Watering: Shallots need nitrogenous fertilizers for leaf formation and bulb production. Nitrogenous fertilizers such as urea may be applied twice during the plant growth: first at the time of land preparation and second during the vegetative growth of the plants. For container-grown plants, foliar application of liquid nitrogen or urea may be given.
The plants need lots of water during its growth. First watering is given soon after planting the bulbs. After that, need-based watering is given. However, watering/irrigation should be withheld before harvesting.
Pest Management: Onions thrips, leek moth larvae, and onion maggots are some of the serious pests of shallots. Application of 4:4:50 Bordeaux mixture containing 2% lubricating-oil emulsion has proved to be effective in controlling these insects. This treatment should be repeated every week or every ten days.
Disease Management: Downy mildew, purple blotch and aster yellow are some of the major diseases of shallots. Downy mildew disease is caused by a fungus known as Peronospora destructor that is prevalent in areas having a high humidity. This disease can effectively be controlled by the sprays of Bordeaux mixture. Purple blotch is caused by the fungus, Alternaria porri that attacks leaves, seed stems, and bulbs. Bordeaux mixture sprays are effective for this disease also. Aster Yellow is a virus disease that affects inflorescence. The affected plants produce malformed inflorescences. Destroying the affected plants may prevent the spread of this viral disease up to some extent. Since the virus is spread by the vectors such as onion flies, controlling g these vectors proved to be effective in controlling aster yellow disease.
Harvesting and Yield: Plants grown for the leaves or ‘green onions’ are harvested within 2-3 months after planting the seed bulbs. Plants grown for the ‘dry bulbs’ are harvested within 3-6 months of planting. Leaves or ‘green onions’ are harvested when the plants reach 15 cm in height or more. Yield of bulbs from one acre area is approx. 10 tons.
Curing Process and Storage: Curing process involves drying the freshly harvested bulbs in a warm, hygienic place for 1-2 weeks. Cured, fresh shallots can be stored in cool, dry area (0 to 4 °C or 32 to 40 °F at 60 to 70% RH) for six months or longer.
Pathological Disorders: During storage also, shallot bulbs are affected by pathological disorders. Most prominent among these disorders is black mold infections. Black mold is caused by a fungus called Aspergillus niger. This disorder can be effectively controlled by proper curing of shallot bulbs followed by hygienic cold storage at optimum storage conditions.
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