Onion.docx

Onion Dr Khushbu Kholiya, Dr K K Misra and Aman Kumar

Scientific Name :-

Allium cepa

Family:-

Liliaceae

Chromosome no :-

2n=2x=16

Origin:-

Central or Southwest Asia,

INTRODUCTION Onion, Allium cepa, is an herbaceous biennial in the family Liliaceae grown for its edible bulb. The stem of the plant is a flattened disc at the base and the tubular leaves form a pseudostem where their sheaths overlap. The leaves are either erect or oblique and there are 3–8 per plant. The onion plant produces pink or white flowers clustered on stalks. The bulbs are formed just above the flattened stem of the plant by overlapping leaves. The bulb is made up of several layers, each corresponding to a leaf. They are are generally oval but shape can be variable and occur in clusters of 3–18 to a plant. The bulb is protected by a membrane which turns to a papery coat. Onion plants can reach a height of 50 cm (20 in) and are grown as annuals, harvested after one growing season. Onion may also be referred to by cultivar and these include red or purple onion, shallots and spring onions or scallions. The origin of the onion has not been conclusively determined although it is likely to be somewhere in South East Asia where the gene pool is most diverse India is the second largest onion growing country in the world. Indian onions are famous for their pungency and are available round the year. Indian onions has two crop cycles, first harvesting starts in November to January and the second harvesting from January to May. The onion is a hardy cool-season biennial but usually grown as annual crop. The onion has narrow, hollow leaves and a base which enlarges to form a bulb. The bulb can be white, yellow, or red and require 80 to 150 days to reach harvest.

The major Onion producing states are Maharashtra, Madhya Pradesh, Karnataka, Gujarat, Rajasthan, Bihar, Andhra Pradesh, Haryana, West Bengal, Uttar Pradesh, Chhattisgarh, Odisha, Tamil Nadu, Jharkhand and Telangana in the country.

History Because onions are small and their tissues leave little or no trace, there is no conclusive opinion about the exact location and time of their birth. Many archaeologists, botanists, and food historians believe onions originated in central Asia. Other research suggests onions were first grown in Iran and West Pakistan. It is presumed our predecessors discovered and started eating wild onions very early – long before farming or even writing was invented. Very likely, this humble vegetable was a staple in the prehistoric diet.Most researchers agree the onion has been cultivated for 5000 years or more. Since onions grew wild in various regions, they were probably consumed for thousands of years and domesticated simultaneously all over the world. Onions may be one of the earliest cultivated crops because they were less perishable than other foods of the time, were transportable, were easy to grow, and could be grown in a variety of soils and climates. In addition, the onion was useful for sustaining human life. Onions prevented thirst and could be dried and preserved for later consumption when food might be scarce. While the place and time of the onion's origin is still a mystery, many documents from very early times describe its importance as a food and its use in art, medicine, and mummification. Onions grew in Chinese gardens as early as 5000 years ago and they are referenced in some of the oldest Vedic writings from India. In Egypt, onions can be traced back to 3500 B.C. There is evidence that the Sumerians were growing onions as early as 2500 B.C. One Sumerian text dated to about 2500 B.C. tells of someone plowing over the city governor's onion patch. In Egypt, onions were considered to be an object of worship. The onion symbolized eternity to the Egyptians who buried onions along with their Pharaohs. The Egyptians saw eternal life in the anatomy of the onion because of its circle-within-a-circle structure. Paintings of onions appear on the inner walls of the pyramids and in the tombs of both the Old Kingdom and the New Kingdom. The onion is mentioned as a funeral offering, and depicted on the

banquet tables of the great feasts – both large, peeled onions and slender, immature ones. They were shown upon the altars of the gods. Frequently, Egyptian priests are pictured holding onions in his hand or covering an altar with a bundle of their leaves or roots. In mummies, onions have frequently been found in the pelvic regions of the body, in the thorax, flattened against the ears, and in front of the collapsed eyes. Flowering onions have been found on the chest, and onions have been found attached to the soles of the feet and along the legs. King Ramses IV, who died in 1160 B.C., was entombed with onions in his eye sockets. Onions were eaten by the Israelites in the Bible. In Numbers 11:5, the children of Israel lament the meager desert diet enforced by the Exodus: "We remember the fish, which we did eat in Egypt freely, the cucumbers and the melons and the leeks and the onions and the garlic." In India as early as the sixth century B.C., the famous medical treatise Charaka – Sanhita celebrates the onion as medicine – a diuretic, good for digestion, the heart, the eyes, and the joints. By the Middle Ages, the three main vegetables of European cuisine were beans, cabbage, and onions. In addition to serving as a food for both the poor and the wealthy, onions were prescribed to alleviate headaches, snakebites, and hair loss. They were also used as rent payments and wedding gifts. Later, the first Pilgrims brought onions with them on the Mayflower. However, they found that strains of wild onions already grew throughout North America. Native American Indians used wild onions in a variety of ways, eating them raw or cooked, as a seasoning or as a vegetable. Such onions were also used in syrups, as poultices, as an ingredient in dyes, and even as toys. According to diaries of colonists, bulb onions were planted as soon as the Pilgrim fathers could clear the land in 1648.

Onions and tears in the eyes Onions are known to make you cry when chopping or cutting them. This is due to the presence of a gas called syn-Propanethial-S-oxide.



It is a compound liquid that acts as what is called a lachrymatory agent - something that causes tears or stings the eyes.



A study published in 8154bec/Nature proposed that it might be possible "to develop a non-lachrymatory onion by suppressing the lachrymatory factor synthase gene while increasing the yield of thiosulphinate.



Thiosulphinate is responsible for the flavour of fresh onion and is converted to compounds that are said to have hypolipodaemic and antiplatelet aggregation effects.



Although downregulating alliinase itself would also lead to a non-lachrymatory onion, its flavour and nutritional value might be compromised."

There are a few ways to help avoid onion tears, these include: 

Cutting onions in a small pool of water, this can help keep the gases from making contact with your eyes.



Using an extractor fan, exhaust hood, or even just opening a window for a fresh source of air can prevent the compounds from irritating the eyes.



Cutting the onion near running water, or a cloud of steam. Seeing as an onion that doesn't make you cry might not taste so good, it is probably best to just cope with the potential tears while chopping onions as they usually do no harm. Nutreative value Nutritional value per 100 g (3.5 oz) Energy

166 kJ (40 kcal)

Carbohydrates

9.34 g

Sugars

4.24 g

Dietary fibre

1.7 g

Fat

0.1 g

Protein

1.1 g

Vitamins

%DV†

Quantity

Thiamine (B1)

4%

0.046 mg

Riboflavin (B2) Niacin (B3)

2%

0.027 mg

1%

0.116 mg

Pantothenic acid (B5) 2%

0.123 mg

Vitamin B6

9%

0.12 mg

Folate (B9)

5%

19 μg

Vitamin C

9%

7.4 mg

Minerals

%DV†

Quantity

Calcium

2%

23 mg

Iron

2%

0.21 mg

Magnesium

3%

10 mg

Manganese

6%

0.129 mg

Phosphorus

4%

29 mg

Potassium

3%

146 mg

Zinc

2%

Other constituents

Quantity

Water

0.17 mg

89.11 g

Fluoride

1.1 µg

USES

Health benefits

Heart health According to Jarzabkowski, onions encourage a healthy heart in many ways, including "lowering blood pressure and lowering heart attack risk." A 2002 study in the journal Thrombosis Research suggested that sulfur acts as a natural blood thinner and prevents blood platelets from aggregating. When platelets cluster, the risk for heart attack or stroke increases. This research further supports a similar 1992 study in Thrombosis Research that focused on sulfurs in garlic. Furthermore, a 1987 animal study in the Journal of Hypertension demonstrated delayed or reduced onset of hypertension with sulfur intake. However, the authors said more research was needed to determine if this benefit might be found in humans. Recently, health researchers have noticed a relationship between messaging molecules called oxylipins and high cholesterol management. A 2016 study in the journal Redox Biology found that consuming onions increases oxylipins that help regulate blood fat levels and levels of cholesterol.

The

quercetin

in

onions may also help prevent plaque buildup in the arteries, which reduces the risk of heart attack and stroke, according to the University of Maryland Medical Center. But since most of the studies in this regard have focused on animals, more research is needed to understand the effects in humans.

Anti-inflammatory Onions’ sulfurs may be effective anti-inflammatory agents, according to a 1990 study in the journal International Archives of Allergy and Applied Immunology. Quercetin has been found to relax the airway muscles and may provide relief of asthma symptoms, according to a 2013 study in the American Journal of Physiology.

Immune system "The polyphenols in onions act as antioxidants, protecting the body against free radicals," said Anne Mauney, a dietitian based in Washington, D.C. Eliminating free radicals can help encourage a strong immune system. According to the University of Maryland Medical Center, the quercetin in onions also reduces allergic reactions by stopping your body from producing histamines, which are what make you sneeze, cry and itch if you're having an allergic reaction.

Cancer A 2015 meta-analysis found that intake of allium vegetables, including onions, were associated with reduced gastric cancer risk. According to World’s Healthiest Foods from the George Mateljan Foundation, eating between one and seven servings of onions per week may help reduce the risk of colorectal, laryngeal and ovarian cancer. Eating several servings of onions a day may help decrease the risk of oral and esophageal cancer. Quercetin may be a powerful anti-cancer agent, according to Jarzabkowski. The University of Maryland Medical Center said that quercetin may especially inhibit cancer cells in "breast, colon, prostate, ovarian, endometrial, and lung tumors."The National Onion Association discussed a recent study from the Netherlands that showed that people who ate onions absorbed twice as much quercetin as those who drank tea, and more than three times as much quercetin as those who ate apples, which are other high-quercetin sources. Red onions are especially high in quercetin, according to the association. Shallots and yellow onions are also good options. White onions contain the least amount of quercetin and other antioxidants.

Onions

may

help with some side effects from cancer treatments, as well. A 2016 study published in Integrative Cancer Therapies found that consuming fresh yellow onion helped lessen insulin resistance and hyperglycemia in breast cancer patients undergoing a form of chemotherapy known to cause insulin resistance.

Digestion The fiber in onions promotes good digestion and helps keep you regular. Additionally, onions contain a special type of soluble fiber called oligofructose, which promotes good bacteria growth in your intestines. One 2005 study in Clinical Gastroenterology and Hepatology found that oligofructose may help prevent and treat types of diarrhea. The phytochemicals in onions

that scavenge free radicals may also reduce your risk of developing gastric ulcers, according to the National Onion Association.

Regulating blood sugar The chromium in onions assists in regulating blood sugar. The sulfur in onions helps lower blood sugar by triggering increased insulin production. One 2010 study in the journal Environmental Health Insights revealed that this might be especially helpful to people with people with diabetes. People with Type 1 and Type 2 diabetes who ate red onions showed lower glucose levels for up to four hours. A 2014 meta-analysis in the journal Nutrition found that patients with Type 2 diabetes saw more normalized liver enzymes and lower glycemic levels when consuming sliced onions.

Bone density in older women A 2009 study in the journal Menopause found that daily consumption of onions improves bone density in women who are going through or have finished menopause. Women who ate onions frequently had a 20 percent lower risk of hip fracture than those who never ate onions.

Health risks While not especially serious, eating onions can cause problems for some people. The carbohydrates in onions may cause gas and bloating, according to National Digestive Diseases Information Clearinghouse. Onions, especially if consumed raw, can worsen heartburn in people who suffer from chronic heartburn or gastric reflux disease, according to one 1990 study in the American Journal of Gastroenterology.

Eating

a large amount of green onions or rapidly increasing your consumption of green onions may interfere with blood thinning drugs, according to the University of Georgia. Green onions contain a high amount of vitamin K, which can decrease blood thinner functioning. It is also possible to have a food intolerance or an allergy to onions, but cases are rare, according to an article in the Journal of Allergy and Clinical Immunology. People with onion allergies may experience red, itchy eyes and rashes if an onion comes into contact with the skin. People with an intolerance to onions may experience nausea, vomiting and other gastric discomfort.

Production

In 2016, world production of dried onions was 93.2 million tonnes, led by China and India producing 26% and 21% of the total, respectively. The Onion Futures Act, passed in 1958, bans the trading of futures contracts on onions in the United States. This prohibition came into force after farmers complained about alleged market manipulation by Sam Siegel and Vincent Kosuga at the Chicago Mercantile Exchange two years earlier. The subsequent investigation provided economists with a unique case study into the effects of futures trading on agricultural prices. The act remains in effect as of 2019.

Onions (dried) production in 2016

Country

(millions of tonnes)

China

23.8

India

19.4

Egypt

3.1

United States

3.0

Iran

2.3

Turkey

2.1

Russia

2.0

World

93.2

IMPROVED VARIETIES

Pusa red, Niphad-404, Ni-207-1, Ni-2-4-l(Ail red), Ni-5-7-1 (white), Pusa Ratnar, Early Guano. Onion N-53: Recommended by the Department of Agriculture, M.S. during 1990 and also released at the National level by All India Coordinated Vegetable Improvement Project in 1987. Suitable for

kharif season in western and northern India. Duration is 90-100 days. Bulbs are medium, flatish round and red in colour. Average yield is 250 quintals per hectare. (MPKV, Rahuri) Developed by selection, improvement over N-53 suitable for kharif season and released in 1986. Bulbs are globose in shape with crimson red colour with 13 % TSS. Duration is 10.0110 days. It has less bolting ability compared to N-53. Average yield is 250 quintals per hectare. MPKY, Rahuri) N-2-4-1: Developed during early sixties for rabi season by the Department of Agriculture, M.S. and recommended at the National level by AH India Coordinated Vegetable Improvement Project in 1985 for Tones IV and VII of India. Bulbs globose in shape with brick red colour, TSS 12-13 per cent. Average yield is 300-350 quintals per hectare. (MPKV, Rahuri) N-257-9-1: It was developed by selection from local material. It was released at MPKV, Rahuri in 1984. Duration is 120 days. Suitable for rabi season. Bulbs are globose in shape with white colour. Average yield is 250 quintals per hectare. (MPKV, Rahuri). Phule Safed: Developed by selection from local germplasm collected from village Kegal of District Kolhapur and released in 1994. Bulbs are globular in shape with white colour. TSS is. 13 per cent. Suitable for dehydration. Average yield is 250 - 300 quintals per hectare.(MPKV, Rahuri). Phule Survarna: It is useful for round the year plantation. Yellow coloured variety suitable for export to Europe, Australia and America. Pungency mild, TSS 11.5 per cent and excellent keeping quality (4-6 months). Suitable for both the rangada and rabi seasons. Yields about 240 quintals per hectare. Besides it is released through the State Variety Release Committee of Maharashtra it is also notified by the Central Sub Committee on Crop Standards, Notification and Varietal Release at the national level. (MPKV Rahuri).

Climatic conditions of Onion Cultivation

Onion grows under a wide range of climatic conditions but mild season without great extremes of heat or cold or excessive rainfall is best suited. It requires a temperature of 12-25°C before bulbing and 15.6-21.loC for bulb formation. The plant is somewhat hardy and can withstand freezing temperature. It can be grown as a rainfed crop at 1500 to 2100 metres elevation between April and August. In places where the annual rainfall exceeds 25 to 100 cm, the onion does not thrive well. It requires 70 % relative humidity. Exposing plants to very low temperature in the beginning favours bolting and hence the transplanting of seedlings before 15th of December (plains) is never recommended. Likewise sudden rise in temperature favours early maturity of the crop which results in small sized bulbs. Thus, delayed transplanting after 15 January is also not desirable as the plants are exposed to high temperature.

SOIL

Onion can be grown in all types of soils such as sandy loam, clay loam, silt loam and heavy soils. However, the best soil for successful onion cultivation is deep, friable loam and alluvial soils with good drainage, moisture holding capacity and sufficient organic matter. In heavy soils, the bulbs produced may be deformed. Onion crop can be grown successfully on heavy soil with application of organic manure prior to planting and preparation of the field for onion cultivation should be very good. The optimum pH range, regardless of soil type, is 6.0 7.5, but onion can also be grown in mild alkaline soils. Onion crop is more sensitive to highly acidic, alkali and saline soils and water logging condition. Onions do not thrive in soils having pH below 6.0 because of trace element deficiencies, or occasionally, Al or Mn toxicity. The threshold electrical conductivity of a saturation extract (ECe) for onion crop is 4.0 dS/m. When the ECe level exceeds this, crop yield starts declining. Season Sowing, transplanting and harvesting timings of onion in different regions of India Season

Time of seed sowing

Time of transplanting Time of harvesting

Maharashtra and some parts of Gujarat 1. Early Kharif

Feb.-Mar.

April-May

Aug.-Sept.

2. Kharif

May-June

July-Aug.

Oct.-Dec.

3. Late Kharif

Aug.-Sept.

Oct.-Nov.

Jan.-Mar.

4. Rabi

Oct.-Nov.

Dec.-Jan

Apr.-May

Tamil Nadu, Karnataka and Andhra Pradesh 1. Early Kharif

Feb.-April

April-June

July-Sept.

2. Kharif

May-June

July-Aug

Oct.-Nov.

3. Rabi

Sept.-Oct.

Nov.-Dec.

Mar.-Apr.

Rajasthan, Haryana, Punjab, UP and Bihar 1. Kharif

June-July

July-Aug.

Oct.-Nov.

2. Rabi

Oct.-Nov.

Dec.-Jan.

May-June

1. Kharif

June-July

Aug.-Sept.

Nov.-Dec.

2. Late Kharif

Aug.-Sept.

Oct.-Nov.

Feb.-Mar.

3. Rabi

Sept.-Oct.

Nov.-Dec.

Mar.-Apr.

1. Rabi

Sept.-Oct.

Oct.-Nov.

June-July

2. Summer (Long day type)

Nov.-Dec.

Feb.-Mar.

Aug.-Oct.

West Bengal and Orissa

Hilly areas

SOWING METHOD

Onions can be grown from seeds, seedlings and bulblets.

Nursery raising Proper nursery management and transplanting are important operations in the onion crop. About 0.05 hectare nursery bed area is enough for getting seedlings to transplant in one hectare. The field should be ploughed 5-6 times to break clods and well pulverized to hold water. The debris of previous crops, weeds and stones should be removed before bed preparation. Apply half ton of well decomposed farmyard manure (FYM) at the time of last ploughing in 0.05 ha and mix well with soil. For raising nursery, raised bed of 10-15 cm height, 1.0 - 1.2 m width and length as per

convenience may be prepared. The distance between beds should be at least 30 cm, so that water movements are uniform and drainage of excess water is possible. Raised bed is recommended for nursery because in the case of flat bed, water moves from one end to the other and there is a possibility of washing away of seeds. Drainage of excess water is also a major problem with the flat bed method of raising seedlings. Application of pre-emergence herbicide pendimethalin @ 0.2% is recommended to control weeds in nursery. About 5-7 kg seeds are required to raise seedlings for one hectare. Before sowing, seeds should be treated with thiram @ 2 g/kg of seed to avoid damage from damping off disease. Application of Trichoderma viride @ 1,250 g / ha is also recommended to manage damping off and raise healthy seedlings. Seeds should be sown in lines at 50 mm to 75 mm apart to facilitate the removal of seedlings for transplanting, quick weeding, spray of pesticides etc. After sowing, the seeds should be covered with fine powdered farmyard manure or compost followed by light watering. Application of water through drip or micro sprinkler irrigation system helps in saving irrigation water (Fig. 2). Foliar spray of benomyl @ 0.2% is recommended to control soil borne diseases in the nursery. When the severity of thrips infestation is high, foliar application of Fipronil or profenopos @ 0.1% is recommended. Seedlings are available for transplanting in 35-40 days after sowing (DAS) for Kharif and 45-50 DAS for late Kharif and Rabi seasons.

Raising small Bulblets

Of green onion for salad in early winter. For this purpose, small onion bulblets of kharif onion varieties like Agrifound Dark Red, Baswant 780, N-53 and Arka Kalyan raised in the previous season are used for planting. Raised beds or flat beds are prepared depending upon the soil type. To cover one square metre area of the bed 15 g of seed are sufficient. The best time of sowing of seeds for getting quality bulblets is mid January to the beginning of February depending upon the area. The plants are left in the nursery bed up to April-May till their tops fall. Harvesting is done along with the tops and selected bulblets (1.5 to 2.00 cm in dia.) are stored by hanging method till July in a well-ventilated house. Such well stored bulblets are used for transplanting in the Kharif season

Broadcasting in Beds/Direct Sowing

Bellary and Dharwar districts of Karnataka, which are thinned later to give proper spacing for development of bulbs. Seeds of small onion (Bangalore Rose, Agrifound Rose and Arka Bindu) are broadcasted in small flat beds which are thinned later. For broadcasting directly in the field or sowing in the row, 20-25 kg seeds per hectare are used. In the plains, seeds are sown in lines 30 cm apart during September-October. After sowing, hand hoeing is done to allow the seeds to reach to a depth of 2.5-3 cm. Hand watering or light irrigation is given immediately after covering the seeds. Weeding is recommended at 10 days interval for preventing smoothering of seedlings by weeds.

PLANTING

Land preparation Organic manures equivalent to 75 kg N/ha (approximately FYM 15 t/ha or poultry manure 7.5 t/ha or vermicompost 7.5 t/ha) should be incorporated at the time of last ploughing and beds with appropriate size should be prepared after leveling. Mostly, flat beds of the size 1.5-2.0 m width and 4-6 m length is formed. However, flat bed should be avoided to prevent water logging during Kharif or rainy season. Water logging favours Anthracnose disease which is most devastating during Kharif season. Broad bed furrows (BBF) of 15 cm height and 120 cm top width with 45 cm furrow are formed to achieve proper spacing and population density. It is suitable for drip and sprinkler irrigation as well. BBF is the best method for Kharif onion production because the excess water can be drained out through the furrow. This improves the aeration and helps in reducing the incidence of Anthracnose disease.

Transplanting Proper care should be taken while selecting seedlings for transplanting. Over and under aged seedlings should be avoided for better establishment. At the time of transplanting, one third of the seedling top should be cut to get good establishment. The onion seedling should be transplanted after dipping roots in carbendazim solution (0.1%) for two hours to reduce the incidence of fungal diseases during the establishment. The optimum spacing is 15 cm between the rows and 10 cm between plants.

Manuring and fertlization Fertilizer schedule for onion (per ha)

Schedule

N

P2O5

K2O

Organic manures

40 kg

Organic manures equivalent to 75 kg N

Kharif onion (Yield potential – 25-30 t/ha) Basal

25 kg

40 kg

(FYM – Approx. 15 t/ha or Poultry manure- Approx. 7.5 t/ha or Vermicompost – 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 or Poultry manure- Approx. 7.5 t/ha or Vermicompost – 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 or Poultry manure- Approx. 7.5 t/ha or Vermicompost – Approx. 7.5 t/ha)

30 DAT

60 kg

-

-

60 DAT

60 kg

-

-

Total

180 kg

60 kg

70 kg

Intercultural operations Control of weeds at the initial growth stages is essential for getting high marketable bulb yield. Because of labour scarcity, chemical control of weeds along with cultural methods is inevitable. Application of Oxyflurofen @ 23.5% EC (1.5 -2.0 ml/L)/ Pendimethalin @ 30% EC (3.5-4ml/L) before transplanting or at the time of transplanting followed by one hand weeding at 40-60 days after transplanting is recommended for efficient weed control. Rotation and Mixed Cropping Onion crop should follow the vegetable crops such as cauliflower, tomato and potato, which require large quantities of organic manures. As a winter crop, it follows cereals, groundnut and cowpea while as a summer crop it follows paddy. When cultivated as monsoon or late monsoon crop, coriander, french bean, sorghum, pearl millet, chillies, and groundnut are planted after harvesting onion. During the initial five months after planting sugarcane, onion is grown as an inter-crop.

Irrigation Irrigation requirement of onion depends upon the season, soil type, method of irrigation and age of the crop. In general, onion needs irrigation at the time of transplanting, three days after transplanting and subsequently at 7-10 days interval depending upon the soil moisture. In general, Kharif crop needs 5-8 irrigations, the late Kharif crop requires 10-12 and Rabi crop needs 12-15 irrigations. Onion being a shallow rooted crop, needs frequent light irrigation to maintain optimum soil moisture for proper growth and bulb development. Irrigation needs to be stopped when the crop attains maturity (10-15 days before harvest) and the top starts falling which helps in reducing the rotting during storage. Excess irrigation is always harmful and dry spell followed by irrigation will result in the splitting of the outer scales and also formation of bolters. Water loss with flood irrigation is too high due to conveyance, seepage and percolation losses. Modern irrigation techniques such as drip and micro sprinkler irrigation help in saving irrigation water and improve the marketable bulb yield significantly. In case of drip irrigation, seedlings need to be planted at a spacing of 10 x 15 cm in a broad bed furrow (BBF) of 15 cm height and 120 cm top width with 45 cm furrow. Each BBF should have two drip laterals at (16 mm size) 60 cm distance with inbuilt emitters. The distance between two inbuilt emitters should be around

30-50 cm and the discharge flow rate is 4 l/hr. In case of micro sprinkler, the distance between two laterals (20 mm) of micro sprinkler should be 6m with a discharge rate of 135 l/hr. The research outcome indicated that the drip irrigation at 100 % Pan Evaporation (PE) significantly improved the marketable bulb yield (15-25%) with higher per cent A grade bulbs, water saving of about 35-40% and labour saving of 25-30% as compared to flood irrigation

Fertigation Fetigation is an effective and efficient method of applying fertilizers through drip irrigation which is used as the carrier and distributor of irrigation water and crop nutrients. Application of fertilizers @ NPK 40:40:60 kg /ha as basal and the remaining 70 kg N in seven splits through drip irrigation is recommended for achieving higher marketable bulb yield and cost benefit ratio. The drip irrigation system not only helps in water saving but also reduces nitrogen losses by leaching into ground water, as in fertigation, fertilizer nutrients are applied in root zone only.

Harvesting Onion is harvested depending upon the purpose for which the crop is planted. 0nion crop is ready for harvesting in five months for dry onion. However, for marketing as green onion, the crop becomes ready in three months after transplanting. When the bulbs developing from the leaf bases of onions are fully formed, the leafy green tops begin to yellow and eventually collapse at a point a little above the top of the bulb, leaving an upright short neck. When the tops "go down" in this way, the bulbs are ready for harvesting. Because all the onions in a crop do not mature at the same time, large-scale commercial growers harvest them when about half the tops have gone down. In kharif season, since tops do not fall, bulbs are harvested soon after the colour of leaves changes to slightly yellow and red pigmentation on bulbs develop. Best time to harvest rabi onion is one week after 50% tops have fallen over. Onions for sale as dried bulbs or for storage should be harvested progressively after tops have started falling over. Since onion bulbs are normally formed at the soil surface, it is sometimes possible in sandy soils to pull the mature bulbs by hand. Where conditions make hand pulling impossible, crop is harvested by loosening the bulbs with a fork or hoe before lifting them. The harvested

crop is left in windrows in the field for a few days until the tops are dry. The windrows should be made so that the green tops cover the bulbs to protect them from sunburn. The leaves are cut leaving about 2-2.5 cm tops above the bulb after complete drying. This practice helps to increase the dry matter content. If tops are cut too close, the neck does not close well and provides entry for decay organisms. Early harvest results in sprouting of the bulbs and late harvest results in formation of secondary roots during storage. In kharif season, late harvesting results in doubles and bolting.

Yield

Irrigated onion crop in rabi season gives an yield of 25-30 t/ha while under rainfed conditions it yields only about 0.7-1.0 t/ha. Onion raised as an intercrop in sugarcane and turmeric, in alleys of young fruit garden and banana garden, gives a yield of 5-9 t/ha. The small sized, pungent, local cluster type onion yields half as compared to the large sized varieties.

Storage

Onions are stored in a well-ventilated place with lot of aeration and sunlight. Onion bulbs are packed in perforated gunny bags and stalked in vertical column, one above the other. However, height of such vertical column should not exceed more than 5 feet and should have sufficient space all around and bottom.

RECAPE

Climate



It requires a temperature of 12-25°C before bulbing



15.6-21. C for bulb formation.



The annual rainfall exceeds 25 to 100 cm

Soil



Onion can be grown in all types of soils



The optimum pH range 6.5-7.5



Onion crop is more sensitive to highly acidic, alkali and saline soils and water logging condition.

Sowing Method



Onions can be grown from seeds, seedlings and bulblets.



Proper nursery management and transplanting are important operations in the onion crop.



Raising small Bulblets



Broadcasting in Beds/Direct Sowing



Planting



Flat beds of the size 1.5-2.0 m width and 4-6 m length is formed.



BBF is the best method for Kharif onion production



Onion needs irrigation at the time of transplanting, three days after transplanting and subsequently at 7-10 days interval depending upon

Irrigation

the soil moisture. 

the late Kharif crop requires 10-12



Rabi crop needs 12-15 irrigations.



Onion is harvested depending upon the purpose for which the crop is planted

Harvesting

Yield



0nion crop is ready for harvesting in five months for dry onion.



Irrigated onion crop in rabi season gives an yield of 25-30 t/hq



while under rainfed conditions it yields only about 0.7-1.0 t/ha.



In alleys of young fruit garden and banana garden, gives a yield of 5-9 t/ha.