production technology of onion

onion prodcution, varieties etc.

1. WELCOME

2. AN ASSIGNMENT ON PRODUCTION TECHNOLOGY OF ONION

3. BY-AVISHA RAM BUDHANI 1 st SEMESTER M.Sc.(HORTICULTURE) ASPEE COLLEGE OF HORTICULTURE & FORESTRY, NAVSARI AGRICULTURAL UNIVERSITY, NAVSARI SUBMITTED TO – Dr. N. B. PATEL ASSOCIATE PROFESSOR DEPARTMENT OF VEGETABLE SCIENCE ASPEE COLLEGE OF HORTICULTURE & FORESTRY, NAVSARI AGRICULTURAL UNIVERSITY, NAVSARI

4. BOTANICAL NAME : Allium cepa L. FAMILY : Alliaceae CHROMOSOME NUMBER : 2n = 2x = 16 Onion is one of the oldest known and most important commercial vegetable crop grown in India. India is the second largest onion growing country in the world. Indian onions are famous for their pungency and are available round the year. Origin place of onion is reported to be Central Asia and Meditteranean region. It is a cool season vegetable. The common onion contains 88.6-92.8% moisture, 0.9-1.6% protein, 0.2% fat, 5.2-9.0% carbohydrates, 50-51mg sulphur and 23-28 calories energy per 100 g of edible portion.

5. BOTANY Onion is herbaceous annual for the edible bulb production and biennial for seed production having bisexual flower and is a highly cross pollinated crop. The flower is an umbel. It is pollinated by bees and other insects. The reason for cross pollination is heteromorphism and male sterility. Flowers are protandrous . The edible portion is a modified stem called bulb and develops underground. Its pungency is due to the presence of a volatile oil called allyl propyl sulphide and red color is because of the pigment anthocyanin and yellow color due to Quercetin . Anti-fungal activities in onion is due to a phenolic factor i.e., Catechol. Modern varieties typically grow to a height of 15 to 45 cm (6 to 18 in). The leaves are yellowish- to bluish green and grow alternately in a flattened, fan-shaped swathe. 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.

6. TAXONOMY Kingdom : Plantae Division : Angiosperms Class : Monocots Order : Asparagales Family : Amaryllidaceae Subfamily : Allioideae Genus : Allium Species : cepa

7. DIFFERENT SPECIES Allium cepa var. cepa – common onion with large bulbs borne singly and propagated through seeds. It is mainly used as salad or other culinary purposes. Allium cepa var. aggregatum – multiplier or potato onion : producing small bulbs borne in clusters and generally propagated through small bulbs. Mainly used in seasoning curries. Also called potato/underground/multiplier onion. It is noted for its hardiness and early ripening than common onion. . Allium cepa var. ascalonium – produces bulbs in clusters on surface of soil. This perennial onion rarely produces seeds and is propagated through bulbs. Also called shallot. Allium cepa var. viviparum / proliferum – not widely cultivated, bulbs are produced in place of umbels and are used for pickling and seasoning. Also called tree onion and is noted for its resistance to virtually all known pests and diseases of onions. Allium schoenoprasum or chives – this is a hardy perennial bunching herb grown for their hollow green leaves. It is propagated by root division. Allium fistulosum – it is a perennial bunching species and is very common in China and Japan and is grown for its edible tops and leaf bases.

8. Shallots – milder and subtle. Used in egg dishes and garnishes.

9. STATISTICS India ranks second in area and third in production of onion. China is the leading producer of onion in the world. The productivity of India for onion is 16t/ha.   Area(‘000 ha) Production(‘000 MT)   2014 - 2015 2015 - 2016 2014 – 2015 2015 - 2016 India 1173 1225 18927 20991   Area(‘000 ha) Production(‘000 tonnes) Productivity(tonnes/ha)   2014 - 2015 Gujarat 44.30 1126.55 25.43

10. In India, per hectare yield is highest in Gujarat followed by Punjab. In Gujarat, onion cultivation is mainly confined to pockets of Bhavnagar and Surendranagar . India ranks third in the export of onion preceded by Netherlands as the leading exporter and Spain as the second leading exporter of onions.

11. Yellow onions - the most popular cooking onions because they add excellent flavor to most stews, soups, and meat dishes. They have a sulfur content and are the most pungent. White onions have a white or off white skin and are a little less pungent as compared to yellow onions. They are majorly used for processing and in Mexican cuisines.

12. Red onions have a mild sweet flavour and suitable for raw consumption in salads and sandwiches

13. DESCRIPTION OF A FEW VARIETIES 1. Red colour varieties Sr. No. Varieties Source Salient characteristics 1. Pusa Red ICAR-IARI, New Delhi Bulbs medium, average weight 70-90g, bronze in colour , flat to globular shape, less pungent, less bolting, good keeping quality. Maturity 125-140 days after transplant. Yields 250-300q/ha. 2. Pusa Ratnar -do- Bulbs oblate to flat, globular, larger, less pungent, neck dropping and bronze deep-red coloured. Fair in storage quality. Produce 300-400q/ha. 3. Pusa Madhavi -do- Bulbs medium to large, light red and flattish- round. Maturity in 130-135 days after transplanting. Keeping quality is good. Yield potential is 300q/ha. 4. Pusa Riddhi   -do- Suitable for  kharif  and  rabi  seasons having compact, flat globe, and dark red colour bulbs. Bulb weight ranges from 70-100g and produce 310q yield/ha. Pungent and rich in antioxidant ( quercetin 107.42mg/100 g). Also suitable for storage and export.

14. 5. Arka Pragati ICAR-IIHR, Bengaluru It has attractive pink coloured globe-shaped bulbs of uniform size with thin neck, high pungency and early maturity. Grown successfully during rabi and kharif in the South. Maturity in 140-145 days after transplanting.  Yields 200q/ha. 6. Arka Niketan -do- Bulbs globular with thin neck, attractive colour , average weight 100-180g, TSS 12-14%, High pungency, can be stored for 5 months at room temp. Maturity 145 day. 7. Arka Kalyan -do- Bulbs globular with deep pink coloured outer scales and fleshy succulent concentric internal scales, weighting 100-190g and give 335q/ha. Tolerant to purple blotch disease. It can be grown successfully in  kharif . 8. Arka Bindu -do- Bulbs are small in size (2.5-3.5cm), deep pink, flattish globe, pungent, high TSS (14-16%), early maturity. Free from early bolting and splitting. Suitable for export particularly to Malaysia to Singapore. Produce 250q yield/ha. 9. Bangalore rose -do- Bulbs are small sized and uniform in colour and size. Suitable for export and yields 150q/ha. 10. Arka Kirtiman (F 1 ) -do- An F 1  hybrid with red bulbs, firm texture, light red flesh, TSS 10%. Shelf life 5 months, good for transport, free from split and bolters. Resistant to biotic stresses. Maturity 120-125 days. Best for AP, Eastern MP and Orissa. Yield ranges from 300-375q/ha.

15. 11. Arka Lalima (F 1 ) -do- Hybrid which produce 500q/ha variety. Bulbs deep red, globe with firm texture, light red flesh, TSS 12%. Shelf life 5 months, good for transport, free from split & bolters. Resistant to biotic stresses. Maturity 130-135 days. 12. Bhima Raj   ICAR-DOGR, Pune   Produces dark red and oval shaped bulbs with single centre and thin neck. TSS ranges from 10-11%. Suitable for  kharif  and late  kharifseason . It can be cultivated during  rabi  season for immediate market. Matures within 120-125 days after transplanting with absolutely no bolters with high percentage of marketable bulbs during  rabi . Stored up to 3 months during  rabiseason . Per hectare yield ranges from 250-300q. 13. Bhima Red   -do- Suitable for  kharif  and late  kharif  season. It can be grown during  rabi  season also for immediate marketing. Bulbs are attractive red in colour with round shape. Yields 480-520q/ha. TSS ranges from 10-11%. Matures in about 115-120 days after transplanting during late  kharif   andrabi  season. 14. Bhima Super -do- Suitable for  kharif  season and can be cultivated during late  kharif . Possesses medium red coloured round bulbs with tapering towards neck. TSS is 10-11%. Produces quality bulbs with maximum number of single centred bulbs. Bulbs attain maturity after 100-110 days after transplanting during  kharif  season. Give 260-280q/ha in  kharif  and 400-450q/ha in late  kharif .

16. 15. Bhima Kiran   -do- Suitable for rabi season. Bulb attains immediate light red colour after harvest. Bulbs are oval to round in shape, have very less number of bolters and doubles in rabi (less than 5%), thin neck, TSS 12%, good keeping quality suitable for storage up to 5-6 months. Matures in 130 days after transplanting and produce 410q/ha. 16. Bhima Shakti   -do- Suitable for late  kharif  as well as  rabi  season. Bulbs attains immediate attractive red colour after harvest. Shape is round. TSS 11.8%. Small to medium neck thickness, uniform neck fall during  rabi  and more than 70% neck fall during late  kharif . Bulbs have very good storage life up to 5-6 months. Bulbs mature in 130 days after transplanting during late  kharif  and  rabiseason . Tolerant to thrips . Yield potential is 420-450q/ha. 17. Agrifound Light Red National Horticultural Research and Development Foundation (NHRDF, Nasik) Bulbs are light Red and globular in shape. Slow bolter. It has good keeping quality. Maturity in 160-165 days after sowing and gave about 300-325q yield/ha. TSS 13%. 18. Agrifound Dark Red -do- Selection from a local stock of  kharif  onion grown in Nasik. Bulbs are dark red, globular in shape with tight skin, moderately pungent. TSS 12-13%. Matures in 150-160 days after sowing. Suitable for  kharif  and late  kahrif . Excellent in keeping quality and yields 300-400q/ha. 

17. 19. Agrifound Rose -do- Developed specially for export purpose. Bulbs flattish round, red, 2.5-3.5 cm in size, TSS 15-16%. Suitable for kharif season in Cuddapah and in all three Karnataka. Bulb matures in 95-110 days from sowing.   20. Hisar-2 CCS, HAU, Hisar Bulbs bronze-red in colour like those of Pusa Red and are top-sided flat-globular, sweet but pungent. Matures in 165 days after sowing. TSS 11.5-13.9%.  Yields 300q/ha. 21. Punjab Naroya PAU, Ludhiana Bulbs are medium to large, red, round with close neck. It takes 120 days from transplanting to harvesting and produce 250-300q/ha yield. Tolerant to purple blotch disease both in seed and bulb crop production. Tolerant to thrips . 22. Punjab Red Round -do- Bulbs are shining red, medium to large, globular and thin skinned. Early maturing and high yielding (300q/ha). It contains comparatively less direct bolters than Punjab selection.

18. 23. Punjab Selection -do- Bulb red, globular in shape, average weight 50-70g, quite firm with good keeping quality. Average yield is 337q/ha. 24. N-53 MPKVP, Rahuri Bulbs are globe shaped medium sized, very attractive, purplish red at harvesting and moderately pungent. Bulbs mature in 150-165 days. Bulb weight and yield is 80-120g and 250-300q/ha, respectively. The neck of bulbs become thin at the time of maturity and leaves remain green. This is the most suitable variety for  kharif  season. 25. N-2-4-1 -do- Pungent and contain 11-13% TSS. The variety has a high-yield potential (250-300q/ha) with good keeping quality. Tolerant to  Alternaria blight and thrips . 26. Baswant-780 -do- Bulbs globular in shape, red, mildly pungent, attractive and free from pre-mature bolting. TSS 11-12%. Average in keeping quality and produce 200-250q yield/ha. Mature in 150-160 days from sowing. Suitable for  kharif  season cultivation. 27. Udaipur-101 MPUAT, Udaipur Bulbs are flattish, globular, red and sweet with less pungent. It is good for salad. Maturity in 150-160 days after sowing with 200-300q yield/ha. TSS 12-14%. 28. Udaipur-103 -do- Bulbs are red but lighter than Udaipur-101, oblate-globular in shape, sweet but slightly more pungent. Maturity in 150-160 days after sowing. TSS 10.5-13%

19. 2. White colour varieties S No. Varieties Source Salient characteristics 1. Pusa White round ICAR-IARI, New Delhi Bulbs are white and roundish flat with TSS 12-13%. Suitable for dehydration. Yields up to 300q/ha. 2. Pusa White flat -do-   Bulbs are white, flat and medium to large in size with TSS 12-14%. Suitable for dehydration. 3. Bhima Shweta   ICAR-DOGR, Pune Suitable for  rabi  season. Bulbs are attractive white in colour , round in shape, very less number of bolters and doubles less than 3%, thin neck, TSS 11.5%, matures in 110-115 day after transplanting and medium in keeping quality up to 3 months. Tolerant to thrips . Yields 350 q/ha. 4. Bhima Shubra   -do- Suitable for  kharif  and late  kharif  season. Bulbs attractive white in colour , oval to round in shape, thin neck, TSS 10.4-11.7% and matures in 112-125. Stored for 2-3 months during latekharif . It has capacity to tolerate environmental fluctuation, hence can be cultivated in all the three seasons. Give yield 240 q/ha ( kharif ) and 380 q/ha (late  kharif ). 5. Agrifound White NHRDF, Nasik Bulbs are white, round, diameter 4-5 cm with TSS 14-15%. Good storage quality and suitable for dehydration. Matures in 160-165 days. Yield ranges from 200-250q/ha.

20. 6. Punjab-48 (S-48) PAU, Ludhiana Bulbs are white, flatish round, very good texture & flavour. Good keeping and storage quality. Suitable for dehydration. 7. Punjab White -do- Bulbs are large, round with white neck. It has high TSS (15%) and suitable for dehydration. Average yield between 250-300q/ha. 8. N-257-9-1 MPKVP, Rahuri Bulbs globe-shaped, white. High yield potential with good keeping quality. Suitable as a  rabicrop . Suitable for dehydration. 9. Udaipur-102 MPUAT, Udaipur Bulb size is 4.5-6.5 cm, white, round to flat. Maturity in 120 days and produce yield 300-350q/ha. TSS is 12%.

21. 3. Yellow colour varieties S No. Varieties Source Salient characteristics 1. Early Grano ICAR-IARI, New Delhi Bulbs are globe shaped, 7-8 cm in diameter and less pungent. Low in TSS (6-7%) but it has good keeping quality with 300-350q yield/ha. Early and harvested 95 days after harvesting. Suitable for hills. Free from bolting. 2. Brown Spanish ICAR-IARI, Regional Station, Katrain A medium long day type variety suitable for hilly areas. Bulbs are thick skinned, less pungent and has excellent storability. It has 13-14% TSS. Average yield is 250-300q/ha. 3. Arka Pitamber ICAR-IIHR, Bangaluru Short-day type. Bulbs uniform, yellow, globe shape, high TSS, firm, good keeping quality, free from splits, bolters and internal doubles. High stable bulb yield. 4. Phule Swarna MPKVP, Rahuri Less pungent, 11.5% TSS having 4-6 months storage life. Suitable for export to Europe, Australia and America. Yield up to 240q/ha.

22. In India, the cultivation of onion is mainly done in two seasons’  viz .,  kharif  and  rabi . Among the above described varieties, the varieties like Pusa Ridhi , Arka Kalyan , Agrifound Dark Red, Agrifound Rose, N-53, Baswant-780, Bhima Raj, Bhima Red, Bhima Super, Bhima Shubra and Bhima Super are recommended for  kharif  season cultivation. Varieties widely cultivated in Gujarat are Talaja Red, Agrifound light red, Bhima Super, Pillipatti ( Junagadh Local).

23. Bulb Shapes: 1) flattened globe; 2) globe; 3) high globe; 4) spindle; 5) Spanish; 6) flat; 7) thick flat; 8) Granex ; 9) top

24. CLIMATE The onion thrives better in cool season; long days favour bulb formation. However, varietal response to the requirement of temperature is different. Some cultivars grow well in mild climatic conditions during kharif season as well, particularly in Maharashtra and in some parts of Gujarat state. It appears, therefore, that under particular set of climatic conditions, a group of certain cultivars should be selected and acclimatized. For ripening, dry weather is favourable . Drought conditions are very harmful for plant growth and bulb formation. Long days are beneficial in the formation of bulbs. Besides length of the days (photoperiod), other factors play important role in the formation of bulbs are light intensity and quality, temperature, planting time, plant growth, availability of nutrients, cultivars, presence of growth substances either endogenously or application of their artificially for raising crop and management practices including plant protection measures. Kharif onion varieties require day length of 10-11 hrs where as rabi varieties relatively higher temperature and 12-13 hrs of day length. Temperature is more imp. t han day length in seed production while photoperiod is more important than temperature for bulb formation.

25. SOIL Onion prefers to grow well and form good size of bulbs in light soil rich in humus, friable, well-drained with ability to retain soil moisture. Avoid always too heavy soils for onion cultivation. For obtaining higher yields, care should be taken that onion is not planted in soil having high acidity and alkalinity. The optimum range of pH is 5.8 to 6.5 for almost all cultivars except Hissar-2 and Punjab Selection which are salt tolerant. PROPAGATION The usual method of propagation of common onion is seed. Tree onions produce top sets or bulbils in the flower cluster. The multiplier or potato onion seldom produces flowers and seed.

26. NURSERY PRACTICES Onion seed is generally sown in raised nursery beds of 15 – 22.5cm height. The surface of beds should be smooth and well leveled. The soil of nursery should be treated with Thiram or Captaf @ 0.2% or 4-5 g/sq. m area. Before sowing, seed should be treated with Thiram @ 2-3g/kg of seed to avoid damage from damping off disease. Stomp ( pendimethalin ) @3.35litres/ha is applied before sowing to manage seeds economically during rainy season. Sowing should be done in lines placed at 5-7 cm distance. The seeds after sowing should be covered with fine powdered FYM or compost followed by light watering by rose can. The beds should be covered with dry grass or straw or sugarcane leaves to maintain required temperature and moisture. The best time for sowing seed for early kharif crop is April-May, for kharif season May-June while the sowing of early rabi or late kharif is done in August-September. For rabi crop sowing is done in September-October. The nursery will be ready for transplanting when plants are of 6-7 weeks old and 0.6-0.9cm in diameter for kharif and 8-9 weeks old for rabi . If younger aged seedlings are transplanted the establishment will be poor. The seed rate for onion is 10-12 kg/ha for rabi and 12-15 kg/ha for kharif . Best time for transplanting for kharif crop is July-Aug while for rabi crop is Dec-Jan. The spacing for planting is 15 x 10 cm.

27. Schedule for sowing, transplanting and harvesting of onion for Gujarat conditions The spacing for Gujarat condition recommended by JAU is 15 cm x 10 cm or for bigger sized bulbs 20 cm x 10 cm.The seedlings are detopped before sowing to control thrips . PREFERENCES Onions produced in Gujarat have a bigger size and are preferred in areas of Punjab, Haryana etc. M edium sized and yellow bulbs are preferred in Gujarat and small sized in Kashmir and surroundings. Red onions are more pungent as compared to white. White onions are highly preferred for processing(flakes, powder). Season Time of sowing Time of transplanting Time of harvesting Kharif May-June July-August October-December Late kharif or early rabi August- September September-October January-March Rabi November-Dec Dec-Jan April-June

28. IRRIGATION Just after transplanting of seedlings light irrigation is essential. Subsequent irrigations should be given as per need of the crop. The quantity of water and its frequency of application depends on crop growth; soil types, planting season, etc. Irrigation should be withheld 15 to 20 days before commencement of maturity; otherwise it will delay the maturity and reduce the quality of bulbs. Critical stages for irrigation in onion are bulb formation and enlargement stages , the irrigations during this period should be attended to carefully. The splitting of the outer scales may be observed when dry spell is followed by irrigation.

29. MANURES AND FERTILIZERS About 200 to 250 quintals of farmyard manure should be incorporated during field preparation. Nitrogen at 60 to 80 kg, phosphorus 40 to 50 kg and potassium 60 to 80 kg per hectare are required for higher yields. Application of whole dose of phosphorus and potassium and half dose of nitrogen is done just before transplanting. The remaining half dose of nitrogen should be top dressed about 25 to 30 days after transplanting when seedlings are well established and growing. Fertilizer dose for Gujarat condition- For Kharif season, apply 37.5 kg N, 50 kg P2O5 and 25 kg K2O per hectare as a basal dose. 37.5 kg N/ha should be applied at one month after transplanting. ( Recommendation by JAU) WEEDING AND INTERCULTURE Weeds are to be kept down to get a good yield of onion. Onion is a poor competitor of weeds. Weedicides can be profitably used for control of weeds. Weeds are controlled by Teronan @2.5kg/ha 3-5 weeks after transplanting. Application of Basalin 1 L/ha immediately after transplanting helps control the weeds. Stomp @ 3.35 l/ha applied immediately after transplanting and before first irrigation with one hand weeding gives the best results. Application of 0.2% Oxyflurofen 23.5 % EC before planting + one hand weeding at 40-60 days after transplanting is recommended for marketable bulb yield and weed control efficiency (65-80%).- Recommendation by DOGR, Pune

30. HARVESTING Harvesting of onion depends on its type and purposes. 1. Onion for greens: The purpose of this type of onion is to get high quality green leaves. Plants are pulled when bulb formation starts. 2. Immature bulb: As per need for the home consumption and supply to the market, immature onion plants are pulled along with bulbs. 3. Mature bulbs: When bulbs become fully mature, the maturity is indicated by drooping of the tops just above the bulb known as neck fall. The tops may be made down manually before 8 to 10 days of harvesting. The harvesting is done by pulling the bulbs. Help of khurpi may be taken. On large scale modified potato digger can be used . YIELD The average yield of big sized onion is 25-30 t/ha, small sized common onion is 16-20t/ha and multiplier onion is 15-18t/ha. The seed yield is 6 to 8 quintals per hectare in case of bulb to seed method and 8 to 10 quintals in case of seed to seed method.

31. CURING Curing is an essential operation after harvesting. It will remove excess moisture from the outer skin and neck of onion bulbs. Curing increases storage life of the onion bulbs. Not only this, curing helps in improving the colour of the skin. Properly cured onion will have tight skin and well dried outer skin. Usually, 10 to 15 days or so will be sufficient for curing the onion bulbs.

32. GRADING Different grades of onion are as follows on the basis of their diameter :- <35mm 35 –50 mm 50 – 60mm 60 –80mm > 80 mm

33. STORAGE In order to protect onion bulbs from rotting, shrivelling sprouting, and supply regularly to the markets, local or distant ones, become inevitable. For storing, the bulbs which are immature, injured, soft and thick necked should be sorted out. Care should be taken that all the bulbs for storing are perfectly healthy and quite dry. Onion bulbs store well at 0° to 1°C temperate and 65-70% RH. The chances of sprouting of bulbs in storage will be negligible if spray of Maliec Hydrazide (MH 40) @ 500ppm is done 15 days before harvesting. Generally, onion bulbs of kharif season crop do not store well. However, handling of kharif onion is not big problem because its production is limited. Kharif onion is taken by Maharashtra, Gujarat and Karnataka states in India and that too on limited area. Another method which are traditional but can also be followed in the interior areas where cold storage facilities are not available. These are:

34. Storing onion on a string: With the help of a rope onion bulbs are tied on their neck arranged in spirally manner around the rope and hanged in the well ventilated shed . Spread onion on floor: The onion bulbs are spread on the floor in the shed making layer of 10 to 15 cm thick. The bulbs are turned time to time and rotten, damaged and sprouted bulbs are removed. Onion bulbs in trays: Onion bulbs are kept in trays or tiers containing 2 to 3 layers of bulbs. These trays or tiers are arranged in well-ventilated room or shed. Bulbs are checked time to time and unwanted bulbs are removed.

35. Storage Environment/ Structures: Low volume low cost onion structure:    This storage structure is suited for 5 to 10 tons capacity. High volume bottom & side ventilated onion storage structure:   The storage structure is suited for 25-50 tons capacity These storage structures reduce storage losses by 20-50% depending upon the period of storage .

36. PROCESSING OF ONION Onion can be processed into a wide variety of products. Minimally processed ready to use or ready to cook fresh onions, onion paste, dehydrated onion flakes, onion powder, onion oil, onion vinegar, onion sauce, pickled onion, onion wine and beverage etc. The demand for the processed products is increasing day by day due to its convenience to handle and use. As per the estimate, approximately 6.75% of the onion produced is going for processing (by counting total losses, consumption, export and bulb seed requirement the remaining percentage is considered for processing).

37. (1) Minimally processed onions: These are peeled and/or cut onions for ready to use that retain its freshness, packed in suitable packaging material and stored at refrigerated conditions or frozen conditions. (2) Onion paste: Onion is grounded yet retaining its freshness. Preparation of minimally processed onions and onion paste entails optimization of proper preservatives and packaging materials to increase the shelf life of these products. (3) Dehydrated onions: Dehydration of onions reduces the bulk to transport and also increases the shelf life of onions significantly due to less moisture, which arrests the growth of microorganism. Dehydrated onion flakes can be processed into onion powder by proper grinding. Onion powder dissolves very easily and reconstitute quickly compared to onion flakes. Onion powder incorporates the flavour of onion in a variety of foods. Use of suitable packaging techniques is the most important to increase the shelf life of dehydrated onion flakes and powder as these are very hygroscopic in nature.

38. (4) Pickles: An age old practice to preserve the onions is by means of a process called pickling. Most widely used pickling for onions are vinegar based pickling and oil based pickling. While vinegar based pickling is popular in the United States and Europe, oil based pickling is widely adopted in Asia and Africa. (5) Oil: It is another flavouring substance which is widely used in the seasonings of processed products. Onion oil is also used as a natural food preservative in some food products. Onion oil can be extracted by different methods like distillation, solvent extraction, super critical fluid extraction etc. (6) Vinegar/Beverage/Sauce: As the onions are rich in sugars and other nutrients they can be processed into onion vinegar and onion wine. Onion can also be processed into onion beverage and onion sauce.

39. Onion waste processing Large amount of onion waste is produced by consumption of onion both domestically and industrially, making it necessary to search for their utilization. The main onion waste include onion skins, two outer fleshy scales and roots generated during industrial peeling and undersized malformed or damaged bulbs. These can be used in different ways. (1) Source of fiber: The skin of an onion bulb was found to be a rich fibre . After harnessing the color from the dry skin by decoloration , the resultant product is converted into a fibrous material which can be used as a fiber supplement. The same fibrous material can be used as a thickening agent and an exemplary use is in making soup. (2) Natural colour : The color extracted from onion skin can be used as a natural dye. The dry skin of onion is found to contain flavonoids. Onion essence which is used as a flavoring agent can also be extracted from the skin of an onion bulb. (3) Bio-gas: Other resultant materials like outer layers, roots and stalks can be anaerobically digested in a bio-digester to produce alternative energy sources like bio-gas.

40. INSECT-PESTS Onion thrips ( Thrips tabaci ): Affected leaves show silvery white blotches which later become brownish. Spring- summer crop affected much by thrips . A long spell of dry weather is favourable for its rapid multiplication whereas heavy rains and humid weather adversely affect its development and multiplication. Control measures: 1. Collect the debris, affected leaves and weeds and destroy them. 2. Follow crop rotation. 3. In the areas where thrips infestation is severe, grow resistant varieties like Nasik Red and Spanish White. 4. Apply Malathion at 0.1 per cent or Phorate 10 G at 1 kg per hectare.

41. Onion maggot ( Hylemia antiquay ): It attacks the tender portion of the bulb remain hiding in the base of the plant and or in the cracks of the soil where they also lay the eggs. Affected plants become yellow to brown and later they dry away. Control measures: 1. Soil application of Thimet 10 G is beneficial. 2. Spray Malathion at 0.05 per cent. 3. Follow crop rotation. Mites ( Rhizoglyphus sp ): These are very small insects. They remain mostly on the under surface of the leaves. They suck the sap of leaves. Affected plants become pale yellow. Crop infested with mites gives sickly appearance. Control measures: 1. Expose infested bulbs to sun for about two-days. 2. Dust the crop with sulphur at the rate of 20 to 25 kg per hectare.

42. Red spider mite ( Tetranychus spp .) spp .)

43. DISEASES Downy mildew ( Peronospora destructor Casp .): In humid atmosphere the downy growth of the fungus develops over the entire leaf surface and seed stalk. In dry weather, only white spots appear on older leaves and the infection spreads to the sheath and seed stalk. Plant growth stunted, leaves become distorted and pale green. Control measures: 1 . Use disease free bulbs. 2. Destroy wild onions and plant debris. 3. Provide proper drainage. 4. Spray the crop with any fungicides like Zineb , Mancozeb and Nabam , Dithane-M-45 (0.2%) Ditolatan (0.1%) after about 20 days of transplanting of seedlings and repeat the spray at 10 to 12 days interval.

44. Onion Smut ( Urocystis cepulae Frost): This disease is more prevalent in temperate regions. The fungus lives in soil. The fungus attacks at all the stage of plant growth. Dark-brown streaks are seen on leaves and stems. The bending and twisting of earlier infected leaves also occurs. Plants die within three to four weeks after emergence. The linear black lesions most commonly appear near the base of the bulb and grow up to fourth scale deep. Control measures: 1. Treat the seed with Thiram or Captan (2 to 3 g/kg seed). 2. Apply Thiram and Captan in furrows just before sowing the seeds. 3. Treat the soil with fumigants like Methyl bromide (1 kg/25 sq meter) or formaldehyde.

45. Iris Yellow Spot

46. Purple blotch ( Alternaria porri ): Incidence starts with appearance of water soaked areas on leaves and seed stalks and soon they become brown in colour and later purplish in centres . Moist weather conditions are favourable . Severity of disease causes falling leaves and seed stalks without forming seeds. The bulbs of the affected plants may rot later. Control measures: 1. Follow long crop rotation. 2. Gave a provision of draining excess water from the field. 3. Prior to sowing, treat the seed with fungicide like Thiram (2.5 g/kg seed). 4. Spray the crop with Meneb , Nabam , Zineb at 0.25 per cent at 10 to 12 days interval. Three sprays will control the disease. 5. Control thrips with regular spray of Malathion 0.2 per cent as infection may set in by A. porri through wounds made by thrips .

47. Onion smudge ( Colletotrichum circinans ): This is fungal disease. White onion in temperate regions affected much. Most of the red cultivars are resistant. The disease may affect onion in field, storage and during transportation. At seedling stage, it may cause damping off. Subcuticular , dark green to black smudge (the minute stroma of the fungus) appears on the bulb, neck or green leaves. Control measures: 1. Proper curing of the bulbs after harvesting is essential. 2. Bulbs may be treated with 0.2 per cent suspension of Thiram , Captan or Difolaton . It is better if such bulbs are used for planting and avoid for human consumption. 3. Spray crop with 0.2 per cent Zineb or Maneb at 7 to 10 days interval.

48. Pink root of onion : This disease is caused by a soil inhabiting fungus ( Pyrenochaeta terrestris Gorenz .). Generally, incidence of disease is noticed when crop reaches maturity though infection took place much earlier through roots. Infected roots become pink then turn to red, purple, brown and black. In severe cases, foliage turns white yellow or brown and ultimately plants die. Bulb formation and enlargement are affected badly. Control measures: 1. Do not grow seedlings in the nursery bed in which soil having inoculums. 2. Follow long term crop rotation, taking care that crop does not grow of the onion family. 3 . If possible, soil may be disinfected.

49. Black mould of onion: This disease causes great loss to onion bulbs in storage. The causal organism is Aspergillus spp. The infection starts from the top i.e. cut portion above the neck and any injury present oil the bulb. The affected tissue becomes water soaked and at first a white mould develops between the scales which follows development of black spores on stalks which can be seen with naked eyes and this mass remains on exterior of the scales and can easily rubbed off. Control measures: 1. Avoid bulb injury during harvesting, curing, transportation and storage. 2. Sort out all the bulbs showing any wound, green and thick neck, doubles etc., and allow only perfectly healthy bulbs for storage. 3. Clean the stores properly and check for sufficient ventilation. The temperature should be below 15°C. Neither any variety is resistant to black mould nor any effective method is available to check the infection in the field.

50. Bacterial soft rot : Onion bulbs are affected by bacterial species in storage. Pseudomonas alliicola , P. cepacia and Erwinia carotovora cause soft rot. In fact, soft rot starts in the field when crop approaching maturity stage. Affected scales become slimy and giving out a foul sulphurous smell. The organisms exist in soil as saprophytes on refuse. They enter the bulbs through wounds. The cutting of the tops at harvest while the necks are still succulent facilitates infection. Control measures: Similar precautions should be taken to this as for black mould.

51. Aster yellow : It is a virus disease. The onion inflorescence when affected becomes abnormal in appearance. Plant growth stunted, leaves become yellow, flatten and crinkle. Control measures: 1 . Control insect vector by regular spray of Rogor or Malathion. 2. Select only healthy bulbs for seed production. 3. Sow only healthy seeds.

52. Bloat or nematode rot: The causal organism of this malady is nematode ( Ditylenchus dipsaci ). Bloat is one of the important seed borne nematodes. Onion crop may be affected at any stage. When seedling is attacked by this nematode it becomes pale, white, twisted and stunted in growth. Leaves become thick and swell which results in splitting of the epidermis. Bulbs also carry nematodes when they are planted for seed crop, new leaves show yellowish specks and remain stunted. Tip of the leaves become necrotic. Infected scales show frosty appearance. Cracks appear in the bulb. Control measures: 1. Provide good drainage. 2. Obtain clean and healthy seed. 3. Follow long crop rotation. 4 . Sow the seeds or bulbs after giving hot water treatment at 46°C for one hour. 5 . Fumigate seeds with Methyl bromide for 24 hours at 24°C that will eradicate the larvae from seed surface. 6. Plough the field during hot summer season.

53. SEED PRODUCTION Besides all management practices, which are required for commercial production of onion crop, the following points may be taken into care of during seed production. 1 . Maintain isolation distance of 1000 m between two cultivars. Onion is a cross-pollinated crop which is effected mainly by honey-bees. 2 . Grow onion for seed either by seed-to-seed or bulb-to-seed method. Generally higher seed yield is obtained by seed-to-seed method and also it is economical because expenses on harvesting and replanting of bulbs are saved. However, high quality seed is produced when onion seed 'crop is raised by bulb because selection of true-to-type bulbs and healthy ones is possible. 3. For seed-to-seed method, seedlings are raised in the month of August and transplanting is done in the month of September. In case of bulb-to-seed method. healthy, disease-free bulbs of medium-sized having 2.5 to 3.0 cm diameter are selected, and planted in the month of October at 30x10 cm. Application of nitrogen 50 to 60 kg, phosphorus 25 to 40 kg and potassium 40 to 45 kg may be done depending upon initial level of fertility. The requirement of seed bulb may be 15 quintals to plant one hectare area.

54. 4. Treat the bulbs with GA3 at 300 ppm for flower initiation and higher yield. 5. Roguing is done before the bulbs are harvested for late maturing bulbs. From the lot only true-to- type of bulbs are picked up for planting, all the off-types as different colour , thick necks, double, bottle necks, under and over-sized bulbs. In the field off-types and diseased plants are removed twice at flowering and fruiting for high quality seed production. 6 . Harvest only fully ripen heads. Dry them in the sun and extract the seed. After winnowing the seeds, they are again dried in the sun to reduce the moisture to 8 to 10 per cent. Store the seeds in sealed containers in which viability will maintain up to 3 to 4 years. However, under ordinary conditions, onion seed can only be stored for one, year.

55. Bolting   : It is a serious disorder of onion. It refers to the emergence of seed stalk prior to time of their formation and adversely affects the formation and development of bulbs. Bolting is an undesirable character because it directly affects the bulb yield of onion. Causes:- Rabi onion starts to bolt at 20-25 O  C temperature. Early transplanting (August) and late (end of December-January) induce bolting in Kharif and Rabi onion, respectively. The restricted or poor vegetative growth also leads to bolting. Low temperature (10-12  O  C). Varietal difference-white cultivars are more sensitive to bolting. Late transplanting of seedlings. Transplanting of aged seedlings of above 10 weeks. Poor supply of nitrogen in nursery and field.

56. Control Adjust the time of transplanting in such a way that the crop may exposed to moderate temperature at bulbing . Maturity of Rabi crop coincides with high temperature compared to kharif crop. Grow non-bolting cultivars like Early Grano , Texas Early Grano , etc. Transplant healthy and 6 to 7 week old seedlings. Supply recommended dose of nitrogen. Cut the seed stalk at early stage.

57. Splitting & doubling of bulbs Causes : Water deficiency at the initial growth stages and irrigation after a long spell of drought Higher quantities of nitrogen Control : Apply scheduled irrigation. Apply recommended quantities of fertilizers.