(Allium cepa L) |
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Onion is an important crop used widely both as a Condiment and
vegetable. It occupies an Area of 19025 (87-88) hectares in Andhra
pradesh. Kurnool, Mahaboobnagar and Cuddapah are important districts.
Onion is rich in riboflavin and calcium.
There are two main seasons
Rabi (Main Crop) - December to April
Kharif June-July to October-November Onion crop is progated mostly by seed and in some parts bulbs are also used.
Loamy soil are highly suited for proper
development of bulbs.Good drainage and irrigation facilitates better crop growth.
Alkalinity or water loggging are not tolerated by onion. Big bulb, 1-2 split under each bulb. Less pungent,suitable all over the state. Similar to Bellari red, popular in North India. Big size, not very high yielder, more pungent. Medium size, red colour bulbs,
pungent tubers, popular in Maharashtra One or more splits small in size, sweetish, the
bulbs are pungent grown extensively in visakhapatnam area. Nursery has to be raised during December, 7-8 kg
of seed/ ha is sown in 500-600 sq m are to transplant one hectare
Plough thoroughly and ad 100 kg of well rotten FYM for 40 q. meteres
area raised in nursery beds of 120 com width and 3 metre lenth are
formed. Seeds are sown in lines. The beds are to benot watered and
hand weeded. In the nursery 0.5% Bordeaux Mixture is to be sprayed at
10 days intervals to prevent damping. The seedlings will be read
with in 45 days.
The land is prepared in to ridges and furrows or
beds and channels depending upon the conditons. The ridges are to
be made at 30 cm apart. The seedlings are planted on both sides of
the ridges at half way on the slope at 7.5 cm distance. In black
soils, they can be placed at a little wider space up to 10 cm. For
seed production a spacing up to 30 cm either way is given. At the
time of transplanting the seedlings are to be dipped in 1% Bordeaux
Mixture. In addition to the FYM, 50 kg N, 40-50 kg P2O5
and 60 kg K2O per hectare are to be given. Nitrogen is appplied in
one or two doses at monthly intervals afer transplanting a top
dressisng Split appliation is recommended for light soils. Damage : Both nymphs and
adults remain at leaf baes and whorls and feed by suckling.
The infestation causes pale witish blotches on leves and in
cases of severe attack, the leves dry from tip downwards.
The development of onion or Garlic bulbs is afected to a great
extent. Spray Methyl parathon 50 EC, 0.05%
1 ml/l or Dimethoate 30 EC 0.06% 2 ml/l of water. In some areas the leaf eating
caterpillars are found. Spray Endosulfan 0.07% 2ml/l of water This is the most common and devastating
disease of onion in the state and is noticed at all stages
of the crop fron November to May. Purple to dark clooured spots
appear on the leaves and as the spots increae in the size and
colour, the leaves turn yellow and whither. In severe cases
the leaf girdle out at the infecteed region, and dry up.
Incidence up to 48% has been observed. It is noticed in the off seson crop in the
form of large oval and grey spots on the leaves.In this case the affected leves gradually turn pale
and dry up. The leaf infection was found up to 3%. The incidence of the above two leaf diseases can be minimised by timely sprays
of Bordeaux mixture 1% fortnightly intervals. This affects the germinating seeds and seedlings in the nursery beds.
The important commercial varieties like Bellary big, Sattenapalli,
Devanapalli, and rayadurga are found susceptible. Drendching the soil with 1% Bordeaux mixture
or wettable Ceresan 0.3% reduces the disease incidence. The onions While in storage are subject to rotting caused y a
bactirium and fungus resuling in a loss upto 30%. Storing of the bulbs in proper aerated and well
ventilated storage structures and eliniating the rotted buls by
periodical turning of the storage heaps are recommende n minising
the losses during storage. Remove debris and disinfect walls of
warehouse with Formaldehye (1 pint in 10 gallons of water )
or copper-sulphate 0.5 kg in 25 lit of water. The seedling transplanted crop comes to harvest
in about 100 days. While raised from bulbs it takes 120 days.
The last irrigation is to be given e days before harvestisng to
facilitate pulling of bulbs. The yields, in case of Bellary variety
ranges from 20-25 t/ha and the smaller bulbs range 10-15 t/ha.
In case of seed production the flower heds are to be harvesed as
and when fipe and dried under shade.About 500 kg of seeed can be
obtained/ha. Two metods are used mostly commonly for the
production of onion seed. The most common is bulb to sed method.
Which involves first producing buls for the market and then
replanting them for seed production, Medium sized bulbs are
selected (2.5 to 3 cm diameter) about 15oo kg/ha of bulbs are
required to transplant. The bulbs are planted by the fist fortnight
of October at a spacing of 30 cm with in the row and 45 cm between
the rows in ridges. About 850 kg of seed can be produced from one
hectare . If large sized bulbs are planted more seed yield can be
obtained (about 1000kg) but it requires more seed rate and larger
space. For nucleus and foundation seed production, the bulb to seed
method shoulod be followed. The storing and transplanting of bulbs
provide an opportunity for selection and roging. However seed to
seed method may producea higher quanity of seed but rouging becomes
problem. |