Transcript L-14_Onionx

Onion
The bulb group consists of a wide
range of under ground vegetables like
onion, garlic, leek, chives and shallot
etc.
Onion and garlic are the most
important among these, being grown
in Himachal Pradesh on commercial
scale especially garlic.
Onion
Botanical Name:
Family:
Chromosome number
Origin :
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Allium cepa L.
Amaryllidaceae
2n=16
Central and South Western Asia
Onion is the most popular and widely grown vegetables in
low and mid hills during winter season.
The onions cultivated in high hills (May-October) and kharif
onion in low hills can be a more profitable venture.
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Pungency in onion is due to an enzymatic reaction only when
tissues are damaged.
It is due to the presence of sulphur bearing compound in
very small quantity in the volatile oil of the plant juice. The
major compound is allyl-propyl-disulphide.
Colour: There are 4 classes –
White
Yellow
Red and
Brown.
Red colour is due to anthocyanin pigment and yellow is due
to quercetin pigment.
Importance and Uses
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The green leaves and immature and mature bulbs are eaten raw
Used in preparation of sauces, soups and seasoning of food on accounts of its
special characteristic pungency.
Also used in processed form e.g. flakes, powder and pickles.
Onions are diuretic, applied on bruises, boils and wounds.
Relieves heat sensation.
Bulb juice is used as smelling on hysterical fits in faintness.
Used to relive insect bites and sour throat.
Results of investigation suggested that onions in the diet may play a part in
preventing heart diseases and other ailments.
Onions are given in jaundice, spleen enlargement & dyspeptic after cooping
in vinegar.
In malarial fever, they are eaten twice a day.
Roasted onion mixed with cumin, sugar candy and butter oil are a demulcent
of great benefit in piles.
The essential oil contains a heart stimulant, increases pulse volume and
frequency of systolic pressure and coronary flow and stimulates the intestinal
smooth musculature and the uterus.
Reduces blood sugar & has lipid lowering effect.
Soils
♠ Soil should be friable, fertile, well drained
and have an abundant supply of humus.
♠ A heavy soil is not desirable that bakes and
crusts after irrigation.
♠ Sandy loam and silt loams are best suited
to it.
♠ The soil pH should be in the range of 5.86.5.
♠ It is sensitive to high acidity and alkalinity.
♣ It
Climate
grows in mild climate without extremes of high and low
temperature
♣ Plants at early stage can withstand the freezing temperature.
♣ Optimum temperature for seed germination should be 20-25oC.
♣ Low temperature and short photoperiods are required for
vegetative growth.
♣ Relatively high temperature and long photoperiods are needed for
bulb development.
♣ It requires 13-21oC for vegetative growth before bulbing and 1625oC for bulb development and 25-30 oC for bulb maturation.
♣ Low temperature (<15 oC) for long period in bulb crop favours
bolting which is not desirable.
♣ Low temperature of about 10-15oC is required for seed stalk
initiation
♣ Under high temperature (18-20oC) plants do not bolt either in
short day or long day.
♣ Long day varieties do not bulb under short day whereas short day
varieties if planted under long day will develop bulbs.
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Photoperiod
Onion is normally regarded as long day plant i.e. bulb formation is promoted
by long day conditions.
The cultivars differ greatly in day length requirement.
Photoperiod requirement in onion is a quantitative character and each cultivar
needs a minimum day length for bulb formation which is known as critical
value.
This critical value in combination with temperature influences bulb initiation.
The so called short day cultivars when passed the critical value limit will
initiate bulb formation and development is continued under long day
conditions.
Conversely, a long day cultivar will not be able to initiate bulb formation unless
its longer critical value of photoperiod is reached.
If onion plants are kept under short day conditions they continue to grow for
over 3 years without bulbing.
Conclusion:
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High percentage of non-bulbous plants if a particular cultivar is exposed to day
length photoperiods less than necessary for bulbing.
Conversely bulb prematurety occurs when cultivar is exposed to day lengths
longer than the required for bulbing resulting in reduced bulb size and low
yields.
Therefore, care must be taken in choosing appropriate cultivar.
Onion cultivars
Common Big Onion (rabi)
Red Coloured
Agrifound Dark Red, Agrifound Light Red, Arka Niketan, Arka
Pragati, Hisar-II, Kalyanpur Red Round, N-2-4-1, Punjab Red
Round, Punjab Selection, Pusa Madhavi (Good Storage), Pusa
Ratnar (Fair in storage), Pusa Red, Udaipur 101, Udaipur 103,
VL-3
Kharif Onion
Arka Kalyan, Arka Pragati, Baswant-780, N=53, Arka Niketan
(can also be grown in late kharif in Mar
White skinned varieties
Pusa White Flut, Pusa White Round, N-257-9-1, Punjab-48,
Udaipur-102
Yellow skinned varieties
Brown Spanish (Long day variety, suitable for growing in hills),
Early Grano (Good for salad, suitable for green onions)
Multiplier Onion
Agrifound Red, CO-1, C-2 (resistant to purple blotch), CO-3
(resistant to thrips), CO-4 (moderately resistant to thrips), MDU-1
Small Onion
Agrifound Rose (pickling type, suitable for export), Arka Bindu
Cultivars suitable for growing in Himachal Pradesh
Patna Red
N-53
Agrifound Dark red
DPO-1 (a variety in pipe line)
Brown Spanish
DPO-1
Patna Red
Planting Time (India)
Season
Time of sowing
Time of transplanting
Harvesting
time
Northern India
Rainy(Kharif )
Winter (rabi)
May- June (July)
July- Aug (Mid Aug)
Nov-Dec
Oct-Nov (Nov)
Dec-Jan (Jan-early
Feb)
May-June
Maharashtra and Parts of Gujrat
Rainy (kharif)
May-June
July Aug
Oct-Dec
Late rainy (kharif) or
early winter (rabi)
Aug-Sept
Sept-Oct
Jan-March
Winter (rabi)
Nov-Dec
Dec-Jan
April-June
Tamilnadu, Karnataka & A.P.
Early rainy (kharif)
April-May
May-June
August
Rainy (kharif)
May-June
July-Aug
Oct-Nov
Winter (rabi)
Sept-Oct)
Nov-Dec
March-April
Nursery Sowing and Transplanting Time
Region
Nursery Sowing
Transplanting Time
Low Hills
1. Mid November (Poly-house)
2. June- July (Kharif onion)
1.December- January
2. July -August
Mid Hills
Mid October – Mid November
December
High Hills April
May - June
►Seedlings become ready for transplanting in 8-10 weeks
time.
►Seedlings must be about 15-20cm in length at the time
of transplanting.
Seed Rate
8-10 kg/ha
Sets
☻These are small dry onion bulbs produced in the previous year.
☻These mature 3-4 weeks earlier and tend to yield higher than
the seeded onions.
☻Commercially used to produce early green onions but also used
for dry bulb production.
Spacing
► 15 cm between rows and 5-8 cm between plants to plant
► Transplanting on ridges is ideal for kharif onion crop.
► Partial prunning of top is done in over-aged tall seedlings
to
augment the stand of the crop. It also provides convenience in
planting.
Soil preparation and transplanting
♣ Onion
should be planted in well pulverized
field.
♣ Plough first with soil turning plough followed
by 4 to 5 ploughings with country plough.
♣ Then carry out leveling.
♣ Onion is normally planted in flat beds however
kharif onion is planted on ridges.
♣ Transplanting should be done during late
afternoon.
Manures and Fertilizers
Open pollinated varieties
FYM (q/ha)
250
N
120
P2O5
(Kg/ha)
75
K2 O
60
☻Full dose of farmyard manure and phosphorus, potassium and
one-half of N should be applied at the time of transplanting.
☻Remaining part of N should be top dressed in two equal halves
at an interval of one month each.
☻Application of S is found to improve quality and pungency
when applied @ 20 kg CaSO4/ha.
Weed control
►Onion is a closely planted and a shallow rooted crop.
►Hand weeding is difficult which may damage the crop.
►Use of chemical weedicide along with one hand weeding at
critical growth stage is beneficial.
►The critical period of crop-weed competition is between 4-8
weeks.
►Application of Alachlor (Lasso) @ 2 litres/ha or
Pendimethalin (Stomp) @ 3 litres/ha in 750 liters of water
before transplanting is beneficial for controlling weeds.
►3 weedings are sufficient to harvest economic crop if
performed 30, 50 and 75 days after transplanting.
Irrigation
╠ Onion needs very careful and frequent irrigation as it is a
shallow rooted crop.
╠ Water requirement of the crop at the initial growth period is
less and increases during later growth stages.
╠ Irrigation is to be applied at an interval of 10-15 days in cool
weather and at a week interval during hot weather.
╠ Bulb formation and bulb enlargement stages (60-100 days
after transplanting) are the critical for water requirement.
╠ Insufficient moisture tends to slow down bulb growth while
over supply causes rotting.
╠ A dry spell may cause splitting of the outer scales.
╠ Generally, 10-12 irrigations are given in rabi season.
╠ Stop irrigation when the tops mature and start falling down.
Growing kharif onions by sets
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Onion sets are small bulbs ( around 0.25-1.0 inch in diameter) grown in
the previous year.
These sets are used as the propagating material for the production of
dry bulbs and bunching onions.
Variety recommended for this crop is N-53.
5-7.5 kg seed is enough to raise sufficient number of sets to plant one
hectare area.
Sowing of seed is done during end of January or beginning of February
(left plants at same place till April).
In April, plants form small sets due to close spacing. The plants are
uprooted and tops are removed.
The sets having 1.5-2.0 cm in diameter and disease free are selected
and stored till July.
About 10q sets are enough to plant one hectare area.
Sets are planted at 10cm apart in rows on both sides of ridges spaced
35-45 cm.
Sets are normally planted by July-August to get an early crop by early
November.
UNUSAUAL ONIONS
Some very different types of onions are available:
 Multiplier Onion or potato onion (A. cepa, Aggregatum
group): sends up multiple tops, each of which produces
small onion bulbs in clumps.
 Egyption
onion or tree onion (A. cepa, Proliferum
group): produces bulblets at the tops of the stalks
instread of flowering.
 Pickling
onions or pearl onions: produces small bulbs
which are pickled & used as condiments.
Harvesting
☻ Onions are ready for dry bulbs harvesting when the tops get dried
(or neck fall stage) and bulbs are mature.
☻ Harvesting at this stage results in higher yield, longer storage life of
bulbs and less neck rot.
☻ The green onions can be harvested from the time they reach pencil
size up until bulbing begins.
☻ To hasten the maturity process, the tops can be rolled down with a
light weight roller when about 10% of the tops have fallen naturally.
☻ Late harvesting results in thick necked bulb, sunken and also poor
storage life.
☻ Desirable to leave 1.5-2.0 cm of the tops attached to the bulb as it
helps to close neck and reduce storage loss.
Yield (q/ha)
Rabi crop
Kharif crop
250-300q/ha
200-250q/ha
Curing
☻Curing or drying of bulbs is an important process to
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remove the excess moisture from the outer skin and
neck of onion.
This helps in
reducing the infection of diseases
minimizes shrinkage due to removal of moisture
from the interiors.
An additional measure for the development of skin
colour.
Practiced to remove field heat before storage of
onion bulbs.
Cont……
Curing cont……
◙ Bulbs are either cured in field or in open shades or by artificial
means before or in storage.
◙ Onions are considered cured when neck is tight and the outer
scales are dried until they rustle.
◙ Thorough curing is essential for 2-3 weeks (kharif crop) alongwith tops when the temperatures are low during winters.
◙ In winter crop, bulbs are cured in field for 3-5 days in wind
row method and cured in shade for 7-10 days to remove field
heat.
◙ Bulbs are artificially cured by passing hot air at 46 oC for 16
hours when temperature is low.
◙ Shade curing improves bulb colour and reduces losses during
storage.
Storage
◙ Onion bulbs have a rest period for about 2 months.
◙ Proper storage is important as higher temperature
induces
sprouting.
◙ Essentials for successful storage are
Thorough ventilation, uniform comparatively low temperature,
low humidity, proper maturity, optimum application of fertilizer,
freedom from disease infection
◙ Bulbs are stored in special houses with thatched roof and sides
covered by bamboo sticks with provision for good air circulation.
◙ Periodical turning is necessary.
◙ Losses in the range of 25-60 %.
◙ Cold storage at 4-6 oC and 65% RH.
◙ RH is lower than the most vegetables
because dampness in
storage cause considerable rot and mold growth.
PHYSIOLOGICAL DISORDERS
1. Bolting
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means emergence of seed stalk prior to time of bulb formation and
adversely affects the formation and development of bulbs.
Possible Reasons
♣ Transplanting of aged seedlings
♣ Early sowing of seeds in the nursery beds which results in
the formation of small sets.
♣ Late transplanting of seedlings
♣ Restricted or poor vegetative growth also leads to bolting.
♣ Sharp fluctuations in temperatures at bulb initiation
stage.
♣ Low temperature (10-12 oC).
♣ Poor supply of nitrogen in nursery and field.
Management
► Time of planting should be adjusted in such a way that the crop may expose
to moderate temperature at bulbing.
► Sowing of nursery at proper time
► Transplant healthy and 6-7 weeks old seedlings.
► Supply recommended dose of nitrogen.
2. Sprouting
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important disorder in storage of
onion and garlic and results in huge
losses.
☻ It is associated with excessive moisture at
maturity and supply of nitrogen.
Management
◙ Adjust
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time of planting in such a way
that harvesting can be done in dry
period
Stop irrigation as soon as bulbs reach
maturity
Spray Maleic hydrazide 2000-2500 ppm
or iron sulphate or borax @ 500-1000
ppm 2-3 weeks prior to harvesting.
Disease Management
Purple Blotch (Alternaria porri)
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disease occurs during favourable environmental
(temperature 28-30 oC & RH 70-90%).
☻ Higher incidence during kharif (62%) as against 38% in rabi.
► Small, sunken, whitish flecks with coloured centers
occur on leaves and flower stalk. Further, large
purple area develops forming dead patches.
► The intensity was observed from 5-25% on bulb crop
& 10-45% on seed crop.
► Disease appears from mid Feb-April.
► The leaves and stem fall down from point of attack.
► Serious constraint in onion seed production in India.
Management
♣ 3 summer ploughings reduce the disease severity.
♣ Dithane-M-45 (0.25%) is effective.
♣ Mancozeb @ 0.25% at 15 days interval is effective &
also cuprous oxide 75WP (0.25%) is effective.
♣ Ecofriendly method: 2 sprays of palma rosa oil
(0.1%) first at the time of appearance and second 15
days later.
conditions
Stemphylium Blight
☻ Appears on onion leaf as well as on leaf stalk.
☻ Infection appears as small yellow to pale orange
spots or streaks in the
middle of leaves/flower stalks on one side.
Management
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Dithane-M-45 (0.25%) alongwith sticker triton can control the disease.
Basal Rot
☻ Rotting of bulbs is caused by Fusarium fungus & bacteria. Basal rot caused
by Fusarium oxyysporium f.sp. cepae is wide spread disease.
► The common symptoms are wilting & rapid
dying of leaves from tips as the plants approach
maturity & roots turn pinkish.
► Later on most of roots rot.
► The bulbs become soft &
► On cutting, a semi watery decay is found
advancing from base of the scales upward.
Management
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Satisfactory control can be achieved by
flooding in non-growing season.
Patna Red, N-257-7-1, Udaipur-103 are
resistant.
Downy Mildew (Peronospora destructor)
☻ Caused in high humid location on the surface of leaves or flower stalk, violeet
growth of fungus is noticed which later become pale green yellow and finallu
the leaves or seed stalk collapse.
☻ In storage, bulbs of infected plant become soft, shrivelled & outer scales
become amber in colour.
► The common symptoms are wilting & rapid dying
of leaves from tips as the plants approach maturity
& roots turn pinkish.
► Lateron most of roots rot-off.
► The bulbs become soft & when cut, a semi watery
decay is found advancing from base of the scales
upward.
Management
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Crop rotation with a 4 year break in onion
cultivation.
Good weed control and field hygine.
Removal of primary infected onion plants.
Spray of 0.2% Zineb.
Onion Smut
☻ Soil borne disease.
☻ It appears as elongated dark slightly thickned areas at the base of seedling.
The black lesions appear near the base of the scales on planting.
☻ The affected leaves bend downward abnormally.
Management
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Seed treatment with 55-85 g of arsan
per 4.5 kg of seed before sowing.
Treatment of soil with thiram
alongwith methocal sticker.
Insect-Pests
Thrips
☻ Thrips tabaci is the major injurious pest of onion & garlic.
► Onion infested with thrips develop spotted appearance on the leaves which
turn into pale white blotches due to drainage of sap.
► The adults hibernate in soil on grass and other plants in the onion field.
► The thrips also over winter in bulbs and act as a source of infection in the
following year.
► Thrips multiply in large number during March and April both on seed and
bulb crop in North India whereas in Nasik area, thrips incidence was even
observed in the Jan & Feb.
Management
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Application of carbosulfan (0.1%)/
malathion(0.05%) or fenitrothion(0.05%)
has proved effective.
Among
synthetic
pyrethroids,
cypermethrin @ 0.0075% has also been
found effective.
Head Borer
☻ The larva cuts the pedical of flower and feeds on stalk
Management
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Spray cypermethrin@ 0.0075%/ [email protected]% or oxy demeton methyl@ 0.025%.
Onion Maggots (Hyleuria antiqua)
☻ Adult appears like housefly.
☻ Maggots are small white and devoid of legs.
► Maggots enter the bulbs through roots and attack the
tender portion.
► Infested plants turn yellowish brown and finally dry
up.
► The affected bulbs rot in storage as infestation leads to
secondary infection by pathogenic organisms.
Management
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Crop rotation should be followed.
Application of folidol M 2%@
Mites
☻Suck sap
☻Turning plants yellow with sickly appearance.
Management
♣ Infested
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bulbs should be
exposed to sun for 2 days.
Dusting of S @ 22 kg/ha is
recommended.