Climate:

Onion is a cool season crop, hardy and performs better under mild climate without extreme cold and hot. Cool temperature during vegetative growth and relatively warmer and sunny weather during bulb formation and maturity is preferable. Proper seedling growth takes place in temperature 20-250C, however, seedlings can withstand low temperature. Temperature of 13-230C is good with short day for vegetative growth and long day conditions with temperature of 18-250C is favourable for bulb growth. Long day varieties do not bulb under short day, however, short day varieties develop early bulbs under long day condition. Sudden rise in temperature in the Rabi season may result in early and small bulb formation. Rabi season varieties require relatively higher temperature and 12-14 hours day length, whereas, Kharif onion varieties require 10-11 hours day length for bulb formation. 

Root: Onion plants have fibrous roots. Fibrous roots arise from the base of the stem leaves rather than from the radicle. They are bushy roots formed by several thin, hairy, and moderately branched roots. Onion root tips containing meristematic cells are used for microscopic study of mitosis cell division stages.

Bulb: The bulbs are composed of shortened, compressed, underground stems surrounded by fleshy modified scale (leaves) that envelop a central bud at the tip of the stem. In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become more dry and brittle.

Flower: When an onion plant prematurely sends out a flower stalk, it’s referred to as onion bolting. Onion bolting is a natural process that occurs when the plant is under stress. While we gardeners may enjoy the beauty and taste of our plants, we mustn’t forget that the plant’s sole purpose is to reproduce

Leaf: Instead the Allium species referred to as scallions make use of the hollow, tubular green leaves growing directly from the bulb. These leaves are used as a vegetable and can be eaten either raw or cooked. Often the leaves are chopped into other dishes and used as garnishes.

Flowering stem: When an onion plant prematurely sends out a flower stalk, it’s referred to as onion bolting. Onion bolting is a natural process that occurs when the plant is under stress. While we gardeners may enjoy the beauty and taste of our plants, we mustn’t forget that the plant’s sole purpose is to reproduce.

Inflorescence (umbel):  An umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs.

Seed: onion seed is also known as kalonji, black onion seed, black caraway, etc. Onion seed constitutes 38% of oil that is responsible for its aromatic flavor. The seeds are used as flavoring agents while cooking.

Soil:

Onion can be grown on a wide range of soil. However, red loam or black soil and sandy loam to silly loam with good drainage facilities and deep friable is highly peffered for onion cultivation. The soil pH of 5.5-6.5 with mild season is preferred for better yield. Adding organic matter while preparing the land will boost the production of onion bulbs.

Soil treatment:

Apply organic manure like FYM/compost/well-decomposed press mud (about 10-15 t/ha FYM. 

Benefits of soil treatment:

Water benefits:

1. Healthy soil acts as a sponge: more rainwater is absorbed and stored in the ground, where it recharges groundwater and aquifers.
2. Healthy soil prevents run-off and erosion, and reduces evaporation.
3. Healthy soil improves water quality by filtering pollutants.

Nutritious food:

1. Healthy soil increases the nutritional value of food and forage.
2. Healthy soil provides plants with the nutrition they need and strengthens plants natural resistance to pests and diseases.

Economic security:

1. Healthy soil improves farm productivity and provides stability.
2. Healthy soil cuts down on inputs, which increases profit.
3. Healthy soil helps withstand extreme weather, floods and drought.

Environmental and health benefits:

1. Healthy soil helps reverse global warming by absorbing carbon from the atmosphere where it acts as a greenhouse gas.
2. Healthy soil provides habitat for soil microbes to flourish.
3. Healthy soil supports greater biodiversity and species stability.

Suitable Soil:

Loam soil:

Loam soil is a mixture of sand, silt and clay that are combined to avoid the negative effects of each type.

These soils are fertile, easy to work with and provide good drainage. Depending on their predominant composition they can be either sandy or clay loam.

As the soils are a perfect balance of soil particles, they are considered to be a gardenes best friend, but still benefit from topping up with additional organic matter.

Sandy soil:

Sandy Soil is light, warm, dry and tends to be acidic and low in nutrients. Sandy soils are often known as light soils due to their high proportion of sand and little clay (clay weighs more than sand).

These soils have quick water drainage and are easy to work with. They are quicker to warm up in spring than clay soils but tend to dry out in summer and suffer from low nutrients that are washed away by rain.

The addition of organic matter can help give plants an additional boost of nutrients by improving the nutrient and water holding capacity of the soil.

Red and yellow soil:

Found in Deccan plateau, Western Ghat, Orissa, and Chhattisgarh.

Characteristics:

The soils are red due to iron oxide in them. The soils form when metamorphic rocks weather away. Rich in potash. Somewhat acidic. Poor in nitrogen, magnesium, lime, phosphorus, and organic matter. Soils are sandy.

Soil and land preparation:

The land should be thoroughly prepared by giving 3 to 4 ploughings to make friable. Land should be brought to fine tilth stage and make weed free. Make sure the land is prepared is such a way that the excessive water can be drained out easily. Supplement the field with 25 tons of well decomposed farm yard manure in last ploughing. Form ridges and furrows in the field. 

Sowing time:

Season	Time of seed sowing	Time of transplanting	Time of harvesting
Maharashtra and some parts of Gujarat
1. Early Kharif2. Kharif3. Late Kharif4. Rabi	Feb.-Mar.May-JuneAug.-Sept.Oct.-Nov.	April-MayJuly-Aug.Oct.-Nov.Dec.-Jan	Aug.-Sept.Oct.-Dec.Jan.-Mar.Apr.-May
Tamil Nadu, Karnataka and Andhra Pradesh
1. Early Kharif2. Kharif3. Rabi	Feb.-AprilMay-JuneSept.-Oct.	April-JuneJuly-AugNov.-Dec.	July-Sept.Oct.-Nov.Mar.-Apr.
Rajasthan, Haryana, Punjab, UP and Bihar
1. Kharif2. Rabi	June-JulyOct.-Nov.	July-Aug.Dec.-Jan.	Oct.-Nov.May-June
West Bengal and Orissa
1. Kharif2. Late Kharif3. Rabi	June-JulyAug.-Sept.Sept.-Oct.	Aug.-Sept.Oct.-Nov.Nov.-Dec.	Nov.-Dec.Feb.-Mar.Mar.-Apr.
Hilly areas
1. Rabi2. Summer (Long day type)	Sept.-Oct.Nov.-Dec.	Oct.-Nov.Feb.-Mar.	June-JulyAug.-Oct.

Seed rate:

Seed rate depends on the variety and method of planting selected. In general, an average seed rate of 10 to 12 kg seeds required for 1 hectare land.

Seed treatment:

Seeds can be treated with Azospirillum @400 gram/kg of seed using rice gruel as adhesive, dry under shade for 30 to 40 minutes and sow them. Apply VAM 1 kg/square metre in the beds along with farm yard manure 10 kg/square metre before sowing.

Nursery raising 

Onion seedling is raised in the nursery beds. Nursery bed size is 0.6-0.8×3 m or 1.2×3-4 m having 15-20 cm height. Number of beds will depend upon the area to be covered. In general, 50-55 beds with 60-70 cm gaps are required for raising seedling for one hectare or 8-9 beds for 1 Kani. Nursery soil is mixed with well rotten FYM and phorate granules to kill any soil born insects. Thiram or captan or carbendazin @ 4-5g/m2 is also applied for eliminating soil borne diseases. Formalin 40% is drenched into nursery soil @ 200-250ml/10L water and the heap is covered with black polyethylene sheet for 7 days. Soil is then turned and left for 4-6 days. Such treated soil is free from all types of soil born insects-diseases. 10-20g SSP is also mixed with the soil. Seed rate is 8-10 kg/ha (1-1.2kg/Kani). Trichoderma viride (1kg/kani) mixed with fine powdered farm yard manure (25kg/Kani) and incorporated into the soil. Seed sowing time is August-September to October or may be extended to First week of November. Time of nursery raising and transplanting should be adjusted in such a way, so that bulbs escape pre -monsoon rain or monsoon during the final stage of maturity in the summer. Seeds are very light and black in colour. Onion seeds can be treated by captan/ thiram/ carbendizam @ 3gm/Kg seeds and Trichoderma viride (4g/kg seeds) before sowing. Line sowing of seeds with spacing of 3-5cm is done. The seeds are covered with fine powdered farmyard manure or compost after sowing and light watering is given. The beds are covered with dry straw or grass to maintain optimum temperature and moisture. Watering is done at alternate day. Dry straw or grass is removed immediately after germination. It is always beneficial to provide net cover over the nursery beds. Seedlings are ready in 35-45 days. Seedlings are also raised in portrays for long distance transpiration.

Methods of sowing:

Planting bulbs in the field: 

Small and medium sized bulbs about 10-12 quintal are dibbled keeping 30 cm distance between lines and 15 cm between bulbs. Irrigation can be applied within one to two days after dibbling.

Transplanting:

Transplanting is done at spacing of 10 cm plant to plant and 15 cm line to line. 

Fertilizer:

Schedule	N	P2O5	K2O	Organic manures
Kharif onion (Yield potential – 25-30 t/ha)
Basal	25 kg	40 kg	40 kg	Organic manures equivalent to 75 kg N(FYM – Approx. 15 t/ha orPoultry manure- Approx. 7.5 t/ha orVermicompost – Approx. 7.5 t/ha)
30 DAT	25 kg	–	–	–
45 DAT	25 kg	–	–	–
Total	75 kg	40 kg	40 kg	–
Late Kharif and Rabi onion (Yield potential- 40-50 t/ha)
Basal	40 kg	40 kg	60 kg	Organic manures equivalent to 75 kg N(FYM – Approx. 15 t/ha orPoultry manure- Approx. 7.5 t/ha orVermicompost – Approx. 7.5 t/ha)
30 DAT	35 kg	–	–
45 DAT	35 kg	–	–
Total	110 kg	40 kg	60 kg
Long day onion (Yield potential-100 t/ha)
Basal	60 kg	60 kg	70 kg	Organic manures equivalent to 75 kg N(FYM – Approx. 15 t/ha orPoultry manure- Approx. 7.5 t/ha orVermicompost – Approx. 7.5 t/ha)
30 DAT	60 kg	–	–
60 DAT	60 kg	–	–
Total	180 kg	60 kg	70 kg

One third of recommended N and full dose of P2O5 and K2O are applied at the time of planting while remaining two third N is applied in two equal splits at 30 and 45 days after planting.

Sulphur management:

In addition to NPK, sulphur is also an essential plant nutrient important for onion crop for improving yield and the pungency of onion bulbs.

Sulphur is recommended as basal dose at the time of transplanting. Application of 15 kg sulphur/ha is sufficient for growing onion crops in soils having sulphur level above 25 kg/ha while 30 kg sulphur/ha is needed for soils having sulphur level below 25 kg/ha for optimum production of onion. Soil application of 50 kg S /ha is recommended for long day onion crops.

Irrigation:

Onion is mainly grown as irrigated crop in India.  Frequency of irrigation depends on soil and climatic conditions.  Requirement of water varies with stages of crop.  It requires less water immediately after establishment of seedlings and consumption goes on increasing with maximum requirement before maturity, around 3 months after transplanting, and thereafter it is reduced.  So irrigate the crop at 13-15 days interval during early stage followed by subsequent irrigations at 7-10 days interval. 

Weeding and inter-culture: 

During early stages of the crop, plants grow slowly and it is essential to remove weeds.  Pre-plant incorporation of Basalin (2 kg a.i./ha) along with one hand weeding at 45 days after transplanting is recommended to control weeds.  Being a shallow rooted crop, deep inter-culture operation is likely to injure roots and reduce yield.  Generally two hoeings are essential for making soil loose and to cover bulbs. 

Insect-pests of Onion:

Onion Thrips:

Thrips are the most important insect pests on onions. Adults are yellowish to yellowish brown with narrow wings. Eggs are laid in clusters in leaf tissues. Numerous nymphs and adults are observed between leaf sheaths and stems lacerating the epidermis of leaves and sucking the exuding cell sap. The affected leaves show silvery blotches which later turn into brownish colour. The leaves get distorted from tips downwards and plant ultimately wilt and dry away. Seedlings are killed due to heavy infestation and the plant growth is retarded. The shape and size of bulbs as well as yield is affected by thrips.

Control: 

Soil application of Phorate or Carbofuran granules (1kg a.i./ha) is also recommended. Alternate spraying of 0.07% Endosulphan (2ml/litre of water), or 0.07% Nuvacron (2ml/litre of water) or 0.01% Cypermethrin (1ml/litre of water) along with a sticker (Triton or Sandovit) at fortnightly intervals controls the insect. 

Head Borer:

The head borer is a serious pest of onion seed crop in Northern India. The larva of this insect cuts the pedicel of the flower and feeds on the stalk. Single larva damages many flower stalks. The fully-grown larva is greenish with dark brown grey lines along the side of body and measures about 35-45 mm in length. 

Control:

Spraying Endosulfan (2-3 ml/litre of water) along with sticker (Triton/ Sandovit) is recommended to control the insect.  

Onion Maggot:

The adults of die insect appear like housefly. The flies lay their eggs on old leaves or on soil and larva enters into soil and damage disc portion of onion bulb. Infested plants turn yellowish brown and finally dry up. The affected bulbs rot in storage. 

Control: 

Regular crop rotation should be followed and Thimet should be applied in the soil before transplanting. 

Cutworms:

The larvae of this insect are seen in nursery beds and newly transplanted onion fields. The tender plants are found damped at ground level during the night Young larvae feed gregariously on foliage but later segregate and enter into soil. Young larvae are yellowish grey and later on become brown, greasy to touch and coil when disturbed. They cut the seedlings at ground level during night and hide during day.

Control: 

Soil application of Carbofuran (1kg a.i./ha) at the time of planting is recommended. 

Chlorpyriphos (5ml/litre of water) also gives good control of this pest.

Diseases of Onion:

Damping-off:

The disease is more prevalent during kharif season and causes about 60-75% damage. High soil, moisture and moderate temperature along with high humidity especially in the rainy season leads to the development of the disease. Two types of symptoms are observed-

Pre-emergence damping-off: The pre-emergence damping off results in seed and seedling rot before these emerge out of the soil.

Post-emergence damping-off: The pathogen attacks the collar region of seedlings on the surface of soil. The collar portion rots and ultimately the seedlings collapse and die. 

Control: 

Healthy seed should be selected for sowing. The seed should be treated with Thiram @ 2g/kg of seed before sowing. Continuous raising of nursery in the same plot should be avoided. The topsoil of nursery should be treated with Thiram @ 5g/m² area of the soil and nursery should be drenched with the same chemical @ 2g/litre of water at fortnightly interval. Soil solarization by spreading 250 gauge polythene sheet over the bed for 30 days before sowing and application of bio-control agent Trichoderma viride in soil @ 1.2kg/ha is also found effective to control damping-off to considerable extent.

Purple Blotch:

It is an important disease prevalent in all the onion growing areas. Hot and humid climate with temperature ranging from 21-30°C and relative humidity (80-90%) favour the development of the disease. It is more common in kharif season. The symptoms occur on leaves and flower stalks as small, sunken, whitish flecks with purple coloured centres. The lesions may girdle leaves/stalk and cause their drooping. The infected plants fail to develop bulbs .The intensity of disease varies from season to season. 

Control:

Use of healthy seeds for planting and crop rotation of 2-3 years with non-related crops checks the disease.  Spraying Mancozeb (0.25%) or Chlorothalonil (0.2%) or Iprodione (0.25%) after one month from transplanting at fortnightly interval reduces the disease incidence. The sticker triton/sandovit should also be mixed in spray solution.

Stemphylium Blight:

The Stemphyliium blight is a serious problem in Northern parts of the country especially in the seed crop. This disease is very common on onion leaves and flower stalks. Infection occur on radial leaves of transplanted seedlings at 3- 4 leaf stage during late March and early April. The symptoms appear as small yellowish to orange flecks or streaks in the middle of the leaves, which soon develop into elongated spindle shaped spots surrounded by pinkish margin. The disease appearing on the inflorescence stalk causes severe damage to the seed crop.

Control: 

Field sanitation and collecting and burning of crop residues minimizes the spread of infection. Spraying Mancozeb (0.25%) along with Monocrotophos (0.05%) with sticker triton on appearance of disease at fortnightly interval controls the disease.

Basal Rot:

The disease incidence is more in the area where onion crop is grown continuously. A moderate temperature of 22-28°C favours disease development. Initially yellowing of leaves and stunted growth of plant is observed and later on, the leaves dry from tip downwards. In early stage of infection, the roots of the plants become pink in colour and rotting take place later. In advanced stage, the bulb starts decaying from lower ends and ultimately whole plant die. 

Control: 

Since the pathogen is soil borne, it is difficult to control disease. Mixed cropping and crop rotation reduce the incidence of disease. Soil solarization by spreading polythene sheet of 250 guage in summer season for 30 days reduces the infectious propagules, which in turn reduces the disease. Seed treatment with Thiram (2 g/kg of seed) and soil application of Carbendazim, Thiophanate Methyl (Topsin-M) or Benomyl @ 0.1% is effective in the controlling the disease. Seedling dip in Carbendazim (0.1%) or with antagonist viz. Pseudomonas cepacis, and Trichoderma viride significantly reduces the basal rot in onion crop. 

Downy Mildew:

The disease is caused by and reported from northern hilly track and plains particularly in high humid locations. The disease is worst in damp conditions and late planting of the crop, application of higher doses of fertilizers and numerous irrigation increased disease severity. Symptoms appear on the surface of leaves or flower stalk as violet growth of fungus, which later becomes pale greenish yellow and finally the leaves or seed stalks collapse. 

Control: 

For managing the disease effectively, onion bulbs meant for seed crop should be exposed to sun for 12 days to destroy the fungus. Spraying with Zineb (0.2%), Karathane (0.1%) or Tridemorph (0.1%) also gives good control of the disease. 

Onion Smut:

The disease occurs in areas where temperature remains below 30°C. Since the fungus remains in soil, disease appears on the cotyledon of the young plant soon after it emerges. Smut appears as elongated dark, slightly thickened areas near the base of seedlings. The black lesions appear near the base of the scales on planting. The affected leaves bend downwards abnormally. On older plants, numerous raised blisters occur near the base of the leaves. The lesions on plant at all stages often expose a black powdery mass of spores. 

Control: 

Treating the seeds with Captan or Thiram (2.5g/kg of seed) before sowing controls the disease. Seed bed treatment with Methyl Bromide (1 kg/25 m².) is effective in controlling the disease.

Onion Smudge:

It occurs on white onion varieties and reduces the market value of the bulbs. The disease is characterized by small dark green to black spots, which appear on the outer scales.

Control: 

Thorough curing of the bulb after harvesting and storing the bulbs in wellventilated rooms can control the disease

Black Mould:

The disease is common in onions stored in hot climates where the temperature ranges between 30- 45⁰C. It is characterized by the black powdery mass of spores that appear on the exterior of the scales. The black spore masses are also seen on inner scales. It reduces the market value of the bulbs.

Control: 

For effective control of die disease, left for drying in the field for two days. These bulbs should be further dried in shade for 10-15 days before storage. Care should be taken to avoid injury to the bulbs during post-harvest handling. The crops should be sprayed with Carbendazim (0.2%) 10-15 days before harvesting.  

Bacterial Brown Rot:

It is very serious disease of onions in storage. The infection occurs through the wounds. The rot begins at the neck of the bulbs which later gives foul smell through the neck when squeezed. 

Control: 

Proper curing and rapid drying of the bulbs after harvesting is essential for controlling the disease. Affected bulbs should be discarded before storage. If rains occur during maturity, spraying of Streptocycline (0.02%) is recommended.

Onion Yellow Dwarf:

This is a viral disease caused by onion yellow dwarf virus. It is transmitted mechanically as well as by insect vectors. The symptoms of the disease are severe stunting of the plants, dwarfing and twisting of the flower stalk. The affected leaves and stems change their normal green colour to various shades of yellow and leaves tend to flatten and crinkle and as a result bend over. 

Control: 

Removal and destruction of the diseased plants checks the spread of the disease. Healthy bulbs should be used for seed production. Spraying of Malathion (0.1%) or Metasystox (0.1%) to control the vectors checks further spread of the disease. 

Anthracnose:

The symptoms appear initially on the leaves as water soaked pale yellow spots, which spreads lengthwise covering entire leaf blade. The affected leaves shrivel and droop down. 

Control: 

Since the pathogen survives on crop debris, sanitation and destruction of infected crop debris helps in reducing the disease. Mancozeb (0.25%), Carbendazim (0.1%) or Thiophanate Methyl (0.1%) as foliar spray is effective against the disease. 

White rot:

The initial symptom of the disease is yellowing and dieback of leaf tips. Scales, stem plate and roots get destroyed. The bulbs become soft and water soaked. White fluffy or cottony growths of mycelium with abundant black sclerotia resembling mustard grain are seen on the infected bulbs.

Control: 

Repeated cultivation of onions on the same piece of land should be avoided. Crop rotation with cereal crops is recommended. 

Seed treatment with Thiram (4 g/kg of seed) and drenching of soil with Mancozeb (0.25%) are effective in controlling the disease. Application of bio-control agents like Trichoderma viride to the soil reduces the disease inoculum. 

Neck rot:

The infection usually takes place in the field and symptoms become evident in storage. It is more severe when moist conditions prevail just before and during harvest and while onions are cured in the field.  Excessive nitrogen and untimely irrigation increases the incidence of this disease, which is more severe in mild than in pungent onions. The fungus causes softening of the scales which appear water soaked. Under moist conditions, a grayish fungal mat develops on the surface of the scales.

Control: 

For effective control of die disease, left for drying in the field for two days. These bulbs should be further dried in shade for 10-15 days before storage. Care should be taken to avoid injury to the bulbs during post-harvest handling. The crops should be sprayed with Carbendazim (0.2%) 10-15 days before harvesting

Harvesting and yield:

Onion is ready for harvest in 3-5 months after transplanting depending on variety.  Harvesting is done by pulling out plants when tops are drooping but still green.  During hot days when soil is hard, bulbs are pulled out with a hand-hoe.  Yield varies with season and variety.  15-25 tonnes of bulbs are expected from one hectare of transplanted crop.  Yield of kharif crop is comparatively low. 

Rainy season onion cultivation:

Onion was grown during rabi season only.  Development of varieties suitable for rainy season is a significant achievement in onion breeding and it resulted in cultivation of onion in kharif season also.  Varieties like N-53, Agrifound Dark Red, Baswant 780 and Arka Kalyan are suitable for growing in rainy season.  For a successful crop, seeds are sown by end of May or June, transplanted in August and harvested in December-January.  In kharif season, yield will be less and ranges from 15-20 t/ha. 

Green onion or Spring onion:

Consumption of green onion is almost equal to that of dry onion in the world.  Both bulbforming and non-bulb forming types are used as green onion.  For green onion production, seeds are sown in August, transplanted in October and harvested after 75-80 days at tender stage.  Varieties like early Grano, Pusa White Flat and Pusa White Round are suitable for green onion purposes.  Yield ranges from 40-45 t/ha.

Post-harvest handling: 

It is estimated that 60-65% of onion produced in India is consumed internally, 5% exported and 30-40% lost by post-harvest damage. 

Curing: 

Sprouting and rotting are common problems in storage since bulbs contain high moisture.  The bulbs should be adequately cured for proper development of skin colour and to remove field heat before storage of bulbs.  It is done till the neck is tight and outer scales are dried.  This will prevent infection of diseases and minimize shrinkage loss.  Bulbs are cured either in field or in open shade or by artificial means before storage.  During kharif season, bulbs are cured for 2-3 weeks along with top.  In rabi, bulbs are cured in field for 3-5 days; tops are cut leaving 2.0-2.5 cm above bulb and again cured for 7-10 days to remove field heat. 

Storage: 

After curing, bulbs are stored in well ventilated rooms by spreading them on dry and damp proof floorings or on racks.  Periodical turning of bulbs and removal of rotten and sprouted bulbs is highly essential.  A pre-harvest spray of maleic hydrazide (2000-2500 ppm) prevents rotting and sprouting of bulbs stored at room temperature.  At BARC, Trombay irradiation of bulbs with very low doses (4000-9000 krads) of gamma rays is effective for preventing sprouting and enhancing storage life of onion bulbs. 

 Bulbs harvested from kharif crop do not store well for long period.  At 0-2-2.2^oC under cold storage, bulbs can be stored for long period.  NHRDF and NAFED erected storage structures in Nasik for helping farmers.  Three types of storage structures, viz., Panipat type 2tiered, 3-tier onion store and 2-tier model were established by Government itself investing heavily. 

Grading:

These necked, bolted and decayed bulbs are removed. Cured bulbs are graded based on size, and depending on market to which it is sent.  Big sized onion is in demand in New Delhi, medium sized in Kolkata, Patna and small sized onion in North Eastern regions of the country. 

Dehydrated onion: 

 Popularity of dehydrated onion is increasing now-a-days.  Advantages of dehydrated onion are storage stability and ease of preparation.  Commercial processing plants prescribes a shrinkage ratio of 7:1 to 17:1 with a moisture content of 4% in final product.  Dehydrated onions are sold in many forms as slices, chopped, minced, granulated and powdered.