Onion Scientific Name Allium cepa Chromosome number 2
Onion Scientific Name Allium cepa Chromosome number 2 n = 16 Family Amaryllidaceae Origin Central and South Western Asia
Different species of Allium S. No. Common Name Chromosome Number Scientific Name 1. Onion 2 n= 16 Allium cepa L. 2. Garlic 2 n= 16, 24 or 32 Allium sativum 3. Chive 2 n =16, 24, 32 A schoenoprasum 4. Welsh/ Japanese bunching onion 2 n=2 x = 16 A fistulosum 5. Leek 2 n= 4 x=32 A ampeloprasum L. var. porrum 6. Great headed garlic 2 n=4 x=32, 6 x=48 A ampeloprasum 7. Shallot 2 n=16 A cepa var. ascalonicum 8. Potato onion/multiplier/ Egyptian ground onion 2 n=16 A cepa var aggregatum 9. Chinese chive 2 n=4 x=32 A tuberosum Rottler ex Spreng.
Varieties There is large variation in the onion varieties Onion varieties are commercially classified into: 1. Common Onion group: Most commonly grown in India 2. Aggregatum group: Potato or multiplier onion, ever- ready onion, shallot 3. Proliferum group: Top, tree or Egyptian onion The varieties of common onion are grouped according to size, colour and pungency There are four classes on the basis of colour: 1. White 2. Yellow 3. Brown 4. Red
Institute Variety Characteristics IARI, Delhi Pusa White Flat Medium to large bulb. TSS 11 -12 % Pusa White Round TSS 12 -13 % Pusa Red Pusa Ratnar Maturity 125 days. ( rabi season) Pusa Madhvi, Pusa Riddhi, Sel-126 IIHR, Bangalore Arka Ujjwal Arka bindu Recommended for export Arka Akshay Arka Lalima Arka Swadista White onion Arka Kalyan Arka Kirthiman Arka Pitambar Others CSK HPKV , Palampur Sona Vishwas Rose onion Nasik Red round bulbs with high keeping quality N-53 Suitable for kharif onion production. Bulbs are medium sized red in colour. Agri Found Dark Red Recommended for summer cultivation in hill and dry temperate zones of Himachal Pradesh. Bulbs are dark. Palam Lohit
Differences between onion and garlic Onion Garlic Allium cepa Allium sativum Bulbs are formed by the attachment of swollen leaf bases to the underground part of the stem A much divided bulb consisting of several cloves covered by a thin white skin The cloves themselves are well developed axillary buds within the thin leaf foliage Leaves are hollow and round Leaves are narrow and flat Leaf bases store food The leaf bases do not store food but mature as dry scales enclosing cloves Flowers are borne in simple umbels at the apex of floral stem In general, garlic do not produce flower stalks. The inflorescence may be partially or not at all exerted, its bulbils forming a swelling somewhere within false stem a few cm above the bulb The flowering stalk of onion is hollow The flowering stalk of garlic is smooth, round and solid for its entire length Pungency is due to allyl-propyl disulphide Pungency is due to diallyl disulfide
Climate • Onion can be grown under a wide range of climatic conditions but mild climate without extremes of high or low temperature are most suitable • 20 -25ºC temperature is optimal for seed germination , 1321ºC for vegetative growth before bulbing and 15. 6 - 25. 1ºC for bulb development ( for vegetative growth lower temperatures and short photoperiod are required, while relatively higher temperature and long photoperiod are needed for bulb development) • Temperature is more important than the day length for seed stalk development • Very low temperature during initial stages of growth induce bolting, while sudden rise in temperature causes early maturity (rabi/ winter season) and also reduces the size of the bulb. At early stage seedlings can withstand freezing
Growth and Development Bulb Formation in onion is governed by many factors viz. , temperature, photoperiod, light quality and intensity, plant size, nutritional, growth substances, etc. Onion adapted to latitudes far away from equator start to initiate bulbing when day length of 14 - 16 hrs is reached such onions are long day onions The cultivars which can initiate and form bulbs under photoperiods of 13 hrs or less are short day onions, equivalent to those found in latitudes which are less than 24º from equator Each cultivar has a minimum day length requirement for bulbing which is called as a critical value Onion is a long day plant w. r. t. bulbing while low temperature and short day conditions is required for vegetative growth So when a short day cultivar is sown under long day condition, bulb formation would be there as critical value shall be achieved but When long day cultivar is sown under short day condition only vegetative growth is there and no bulb formation is there
• Light Quality: Extension of day length with incandescent light is quite effective in promoting bulbing. Far-red light or blue light accelerated bulbing while red light suppressed bulbing • Light Intensity: Higher the light intensity more rapid is bulbing and ripening • Temperature: Temperature in the range of 25 -30ºC result in rapid bulbing in comparison to 20, 15&10ºC Bulb development is retarded when max. day temperature reaches 40 -45ºC For bulbing early cultivars perform better at warmer climate while late cultivars give better performance at cooler temperature
• Leaves and Carbohydrates: Leaves receive the external stimulus of photoperiod from environment and enhance the physiological activity. The response of long days in relation to bulb formation is there only if there is sufficient accumulation of sugars in plants both for maintenance of root system and bulb formation. • Plant size: Physiological age of the plant is important in triggering initiation of bulbing especially in short day cultivars. Age, amount of stored food triggers the mechanism that initiates bulbing in proper day length and temperature conditions
• Soil – soil should be rich in humus. Onion is sensitive to high acidity and produces a maximum yield in fairly narrow range of soil reaction i. e. 5. 8 -6. 5. Season Time Of Sowing Time Of Transplanting Time Of Harvesting Maharashtra And Parts Of Gujarat Rainy ( Kharif) May -June July August October December Late Rainy Or Early Winter August September October January March Winter November December January April June Tamil Nadu, Karnataka Andhra Pradesh Early Rainy April May June August Rainy May June July August October November Winter September October November December March April Rajasthan, Uttar Pradesh , Haryana , Bihar, Punjab, West Bengal And Orissa Rainy May June July August November December Winter October November December January May June Hills Winter September -October November June-July Summer ( Long Day type) Oct End To Early Nov March August September
Spacing- 15 X 10 cm Seed rate – 8 -10 kg for nursery sowing 25 kg for direct planting Manures and fertilizers : FYM N P K 25 t/ha 73 kg/ha 36 kg/ha 68 kg/ha 125: 60: 100 kg/ha N: P: K is recommended dose for Punjab One third of nitrogen, half potassium and whole phosphorous are applied as basal dose along with FYM. Rest nitrogen and potassium during crop growth. Irrigation – the cylindrical leaf of onion is effective for dissipating heat in the air since it has the highest heat transfer per unit area. Onion is a shallow rooted crop. Water requirement in initial growth period is less and increases at the time of bulb formation. A dry spell followed by irrigation may cause splitting of the outer scales. Irrigation should be stopped 15 -20 days before attaining maturity. Frequent irrigations delays maturity.
Weeding – being a shallow rooted crop any root pruning by cultivation reduces bulb growth. so very shallow cultural operations should always be followed. The most commonly used Chemical weedicide is chloro-IPC @ 5 -6 kg/ha. Basalin @1 l/ha applied one week after transplanting checks most of the weeds. Harvesting – maturity is indicated by the tops dropping just above the bulb while the leaves are still green. Average yield is 25 -30 t/ha. Grading and Storage – onions should be cured , cleaned and graded before storage. All the open necks, bottle necks and injured bulbs are rejected. The Indian Standard Institution has fixed three grades for onions in India. Storage is done at well ventilated place With low humidity preferably at 0°C
Kharif onion In Maharashtra early season (kharif ) onion is transplanted in July end or beginning of August , whereas the rainy season onion is planted by mid October. Transplanting is done in ridges. Variety N- 53 is suitable for kharif onion production.
Cultivation in Himachal Pradesh Varieties recommended Nasik Red round bulbs with high keeping quality N-53 Suitable for kharif onion production. Bulbs are medium sized red in colour. Agri Found Dark Red Recommended for summer cultivation in hill and dry temperate zones of Himachal Pradesh. Bulbs are dark. Palam Lohit Sowing time : Low Hills – November December Mid Hills – October November High Hills – April Seed rate : 10 -15 kg/ha Spacing : 15 X 10 cm
Recommended manure and fertilizer dose FYM N: P: K CAN SSP MOP 25 t/ha 125: 75: 60 kg/ha 500 kg/ha 475 kg/ha 100 kg/ha Apply whole of FYM, SSP and MOP and half of CAN at the time of field preparation and remaining quantity of CAN in two splits at monthly interval after transplanting.
Production of green onion • Green onions are generally produced in lower areas during off season and are available in the market in October – November when the price of bulbs are very high • Varieties : the sets or seedlings of main varieties are used for green onion production , but by seed , thick sowing is recommended. • Sowing time : low hills- July August • Seed rate- 25 -30 kg/ha • Spacing - 15 X 7. 5 cm • Manures and fertilizers same as main season crop
Insect pest and diseases Insect/pest Symptom Management Downy mildew Peronospora destructor Downy growth on infected parts followed by necrotic lesions. Spray the crop with ridomil MZ(250 g/ 100 l) at the time of disease appearance. Repeat at 15 -20 days interval, if needed Purple blotch Alternaria porri Purple zonated spots appear on flowering stalks. The stalks usually break at the point. Immerse the bulbs before sowing in dithane M-45 (250 g/100 L) solution and spray the crop at fortnightly interval with the same concentration of the fungicide starting from the first appearance of disease symptoms. Onion smut Urocystic cepulae Important diseases in areas where temperature remains below 30°C. Treat seeds with arasan or ceresan rot Fusarium and bacteria These attack storage onion. Bacterial soft rot fives out foul odour and fusarium rot is semi watery rot from the base of the scale upwards Store in well ventilated room s Store at temperature just above 0°C Stemphylium blight Stemphhylium spp Purplish green coloured elongated spots appear on leaves /stalk resulting in blight Same as purple blotch
Pest Damage Management Aster yellow Caused by virus. The inflorescence becomes abnormal in appearance Spray Imidicloprid @ 0. 005 % for control of vector. Onion thrips Cause serious damage to onion shoots from February to may and produce whitish spots followed by drying of leaves Spray malathion 0. 05 % or carbaryl 0. 1 % Onion maggots The adult resemble housefly but is Spray bordeaux mixture smaller. the eggs are laid in soil near 4: 4: 50 or use aldrin or base of plant. Maggots feed on plant. dieldrin Head borer Larva cut the pedicel of the flower and feed on stalk which on maturation pupate inside scape. Spray endosulfan @ 2 -3 ml/l Nematodes Onion stem and bulb nematode infests the crop Soil fumigation before sowing Crop rotation
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