Horticulture :: Vegetables :: Small onion

Small Onion/Aggregatum
Allium cepa var. aggregatum
Alliaceae

Varieties
Co 1, Co 2, Co 3, Co 4 and MDU 1, Co (On) 5 (free flowering and seed setting type) are commonly cultivated.

Co 4 CO(On) 5

Soil
Red loam to black soils with good drainage facilities is highly suited for onion cultivation. It performs well at a soil pH range of 6-7 and a mild season without extremes of heat and cold.

Season
Sow the medium sized bulbs during April – May and October – November. It requires sufficient soil moisture during its growing period but heavy rains during bulb germination and bulb formation affects the crop growth.

Seed rate
1000 kg/ha is required. Medium sized bulbs are to be chosen for planting. Seeds @ 8kg/ha.

Raising seedlings and transplanting
This is the most common method practiced for irrigated crop as it results in high yield and large size bulbs. In plains, seeds are sown during October-November for a rabi crop. In hills, seeds are sown from March to June. Seeds are first sown in well prepared nursery beds of 90-120 cm width, 7.5-10.0 cm height and convenient length. Ratio between nursery area and main field is about 1:20. Seed rate varies from 8 to 10 kg/ha. Seedlings of 15 cm height and 0.8 cm neck diameter are ideal for transplanting and this is achieved in 8 weeks. However, it varies from 6-10 weeks depending on soil, climate and receipt of rain. There is a practice of topping seedlings at the time of transplanting if seedlings are over-grown.

Preparation of field
Plough the land to a fine tilth and form ridges and furrows at 45 cm spacing. Sow the bulbs on both the sides of the ridges at 10 cm apart.

Irrigation
Irrigate at the time of planting of seedlings and third day and later at weekly intervals. Withhold irrigation 10 days before harvest.

Application of fertilizers
Apply FYM 25 t/ha, Azospirillum 2 kg and Phosphobacteria 2 kg/ha, N 30 kg, P 60 kg and K 30 kg/ha as basal and 30 kg N/ha on 30th day of sowing.

Fertigation
Apply a dose of 75% of the total recommended dose of superphosphate i.e. 285 kg/ha as basal dose. Azospirillum and Phosphobacteria each @ 2 Kg/ha along with FYM 50 Kg and Neem cake @ 100 kg are applied before last ploughing. Raised beds of 120 cm are formed at an interval of 30 cm and the laterals are placed at the centre of each bed.

Planting design
Bulbs or seedlings are planted in rows of 20 cm spacing and 12 cm between plants. Planting is done at 6 rows in each bed, thereby it accommodates 55,560 plants in one hectare. Irrigation is done after transplanting or planting the bulbs. Complete wetting is necessary to maintain uniform moisture level.

Plant protection
Pests
Thrips and onion fly

Spray any one of the following insecticides based on the ETL of 1 maggot/hill

Insecticide Dose
Dimethoate 30 % EC 7.0 ml /10 lit
Oxydemeton –Methyl 25 % EC 1.2 ml/lit.
Quinalphos 25 % EC 1.2 ml/lit.


Cutworm
Drench the soil with Chlorpyriphos @ 2 ml/lit. for control.

Diseases
Leaf spot
Spray Mancozeb 2 gm/lit or Copper oxychloride 2.5 gm/lit and add Teepol 0.5 ml/lit to the spray fluid.

Basal rot
Seed or bulb treatment with Trichoderma viride, @ 4g/kg and basal application of T. viride,@2.5kg/ha along with VAM 12.5 kg/ha.

(or)

Follow the following IPM practices for pest and disease management

  • Growing two rows of maize as barrier crops around field border.
  • Selection of healthy onion seed bulbs.
  • Bulb treatment –Pseudomonas fluorescens (5 g/kg) + Trichoderma viride (5 g/kg)
  • Soil application of P.fluorescens (1.25 Kg/ha) + T.viride (1.25 kg/ha) + AM Fungi (VAM) (12.5 kg/ha) + Azophos (4kg/ha) + Neem cake 250 kg/ha.
  • Installation of Yellow sticky traps 12/ha for thrips and leaf miner trapping.
  • Installation of Pheromone traps 12/ha for cut wrom (S.litura).
  • Spray application of P.fluorescens (5 g/l) + Beauveria bassiana (10 g/l) on 30 DAP.
  • Spray application of Azadairachtin 1% (2 ml/l) on 40 DAP.
  • Need based application of Profenophos (2 ml/l) or Dimethoate (2 ml/l) or Triazophos (2 ml/l) for thrips/leaf miner/cut worm management.
  • Need based application of Tebuconazole (1.5) ml/l) or Mancozeb (2 g/l)/Zineb (2g/l) for purple blotch disease management.

Harvest and Yield
Spray Cycocel @ 200ppm + carbendazim @ 1000 ppm 30 days before harvest to extend the shelf life of onion. Harvesting is done by pulling out plants when tops are drooping but still green. During hot days when soil is hard, bulbs are pulled out with a hand-hoe.12-16 t/ha in 70 to 90 days. 18 t/ha in 90 days for CO (On) 5 onion. Clean and dry the bulbs for 4 days in shade soon after harvest.

Market Information

Crop Growing districts

:

Perambalur, Trichy, Dindigul, Namakkal, Coimbatore, Erode, Tirunelveli

Major markets in Tamil Nadu

:

Dindigul, Palani, Palladam, Madurai, Trichy, Ottanchathiram, Coimbatore and Chennai

Preferred Varieties

:

Co (On) 5

Grade Specification

:

Shape, Size, skin colour, moisture content

Updated on : 26.08.2013

 

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