Onion Farming in Polyhouse for Maximum Profits

A step by step guide to onion farming in polyhouse

Cool, so you have decided to grow onions for profit and more yield right?, well you are i roght place to learn the Onion farming in polyhouse. Onion is considered as one of the main important vegetable crops. It occupies an economically very important place among vegetables in the country. Onion is also called as the bulb onion or common onion. Onion is a vegetable that is the most commonly cultivated species of the genus Allium. Onions are bulb-shaped vegetables that produce underground.

Today, India is the second-largest onion growing country in the world. Indian onions are famous for their pungency and are obtainable round the year. Indian onions have two crop cycles, first harvesting starts in November to January and the second harvesting from January to May.

Onion can be used generally chopped or sliced in almost every type of foods. It is one of the fundamentals of Indian cooking. It is generally used as a base for curries or made into a paste and eaten as a main course or as a side dish.

The major Onion producing states in the country are Maharashtra, Madhya Pradesh, Karnataka, Gujarat, Rajasthan, Bihar, Andhra Pradesh, Haryana, West Bengal, Uttar Pradesh, Chhattisgarh, Odisha, Tamil Nadu, Jharkhand, and Telangana.

Varieties of onion for polyhouse production:

Let us discuss different varieties of Onions;

• Multiplier Onion – Co­ 1, Co­ 2, MDU­ 1, Agrifound Red
• Spanish Brown – Bhima Light Red, Bhima Kiran, Phule Suvarna, Arka Niketan, Arka Kirthiman
• Small Common Onion – Agrifound Rose, Arka Bindu
• White Onion – Bhima Shubra, Bhima Shweta, Bhima Safed, Pusa White Round, Arka Yojith, Pusa White Flat, Udaipur ­102, Phule Safed, N­257­9­1, Agrifound White.
• Red onion – Bhima Super, Bhima Red, Bhima Raj, Bhima Dark Red, Bhima Shakti, Punjab Selection, Pusa Red, N­2­-4­-1, Pusa Madhavi, Arka Kalyan, Arka Lalima.

Site Selection for Onion farming in polyhouse:

Onions must be grown on friable soils, which contain high amounts of organic matter and have good water-infiltration rates and good moisture-holding capacity. The soil should not be compacted, and the pH level should be 5.8 to 6.6. Sandy loams and muck soils are often used for Onion production in polyhouse. For sweet Spanish onion production, soils with low sulfur levels (below 40 ppm) should be recommended.

Climate for Onion production:

Although it is a temperate crop, Onion cultivation in polyhouse can be possible under sub-tropical, temperate or tropical climate. Mild, gentle weather that is not too rainy, too cold or too hot is ideal for Onion farming. However, Onion can withstand extreme weather conditions at the younger stage. Short day onions that need 10 to 12 hours of day length are grown in plains while long-day onions requiring 13 to 14 hours of day length are grown in the hilly areas.

Seedling stage:

Age of the seedlings is very important for the establishment and higher final bulb yield. Seedlings are ready for transplanting at 45 to 55 days after sowing or when 3-4 true leaves emerge; this is just before bulb formation starts. If seedlings overstay on beds for more than 60 days after sowing, bulb formation starts and potential for bulb size development reduced with consequent important yield reduction.

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Onion seed rate per hectare:

The seed quantity required to the seedling for the one-hectare main field is about 5 to 7kg purchased from some reliable source. For direct sowing, the seed required in the main field is about 1.6 to 2.0 kg of certified seed.

Irrigation requirement for Onion farming:

Onion crop irrigation depends on the season of planting, type of soil, irrigation process and age of the crop. Normally, irrigation is done at the time of seedling plantation, during the transplantation period, 3 days after transplantation and subsequently at regular intervals depending on the moisture content in the soil.

The last irrigation is done ten days before harvesting Onion. Being a shallow-rooted crop, onions require small amounts of irrigation at regular intervals. This helps to keep optimal soil temperature and moisture for growth and bulb development.

Excess irrigation followed by dry spell would effect in bolter formation and splitting of outer scales. Modern irrigation techniques like drip irrigation and sprinkler irrigation are used as they help prevent excess water loss. These techniques help keep the ideal moisture level in the soil. Also, dispensing water through drip or sprinkler irrigation emitter would ensure water at the root of the plant. It prevents water seepage into the soil and hence water loss to a great extent.

Procedure for Onion farming in polyhouse:

• Check the temperature for Onion farming in polyhouse. Green onions are cool-season crops that grow best when the temperature ranges from 55 to 75°F.
• Sweet and dry onions thrive at this temperature range before the bulbs form. Lower the polyhouse temperature by opening louvers, running exhaust fans or by using a cooler. Increase the temperature by turning on a heater.
• Start sweet and bulb onion plants in the polyhouse 10 to 12 weeks before transplanting outside. Plant sweet and bulb onion seeds in flats and green onion seeds in six-inch deep containers.
• Fill the flats and containers with a sterile potting soil mix or soilless media to begin the onion seeds. Select soil with a pH level of 5.8 to 6.6. Apply a fertilizer with a grade of 5-10-10. Sow seed 1/2 inch deep and sets one to two inches deep.
• Place a heating mat or cable under the flats and containers of newly planted onion seeds to hasten seed germination. At 70 to 72°F, the plants emerge through the soil in 6 to 12 days. When the plants emerge, give a 60 to 65°F daytime and 55 to 60°F night time polyhouse temperature. They will grow best in at least ten hours of sunlight per day.
• Harvest onions when the plants are at least 6 inches tall and 1/2 inch to 1 inch in diameter. In a polyhouse, harvest onions about 30 days after planting sets or 40 to 50 days from planting a seed.

Transplanting method:

The Onion seeds are planted in the nursery beds, and the seedlings, thus raised are then carefully lifted and planted in the field. As per the cultivation practices, seedbeds are 125 cm wide and 300 cm long should be raised above the ground level. 5 to 6 Kg of seeds are broadcast uniformly or sown in rows for one hectare. After 6 to 8 weeks time seedlings are ready for transplantation. The spacing depends on the variety and size of the bulbs. Majority of the farmer’s transplant the seedlings in flat plots of several sizes which depending on the level of the field. Onion is grown as an intercrop with banana, spinach.

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Fertigation:

Apply a dose of 75% of the total recommended dose of superphosphate that is 285 kg/ha as a basal dose. Azospirillum and Phosphobacteria each quantity 2 Kg/ha along with FYM 50 Kg and Neem cake @ 100 kg are applied before the last plowing. Raised beds of 120 cm are produced at an interval of 30 cm and the laterals are placed at the center of each bed.

Weed control measures of onion:

Onions do not compete well with weeds. Good weed control requires the integration of cultural methods and chemical methods. Herbicides will give preemergence and postemergence control of annual weeds but repeat applications may be necessary. Cultivation and hand weeding are generally required to supplement chemical control. Onions must be planted in soil where the annual weed seed population has been reduced by cultural procedures such as crop rotation, fallowing or stale seedbed.

Specialty onions can be successfully developed by transplanting through black plastic mulch. This process provides excellent weed control and crop growth.

Care should be taken to avoid fields where residual herbicides from previous years persist in the soil as crop injury may occur.

Onion pests and diseases:

Pests

Thrips- Spray Malathion or Nuvacron (0.1%).

Borer- Spray Endosulfan (0.1%).

Maggot- Apply Thimet 10G to soil and spray Malathion (0.05%).

Diseases

Downy mildew- Spray Difolatan (0.1%) or Dithane M-45 (0.2%).

Smut – Spray Captan, Biltox or Thiram 75%.

Harvest and Storage of onions:

• Most dry onions are generally harvested when one-third to one-half of the tops have fallen over. Bulbs are normally pulled from the soil after being loosened with a disk. They are then topped approximately one inch above the bulb.
• To prevent rot organisms from entering the bulb, onions should be adequately cured in the field, in open shade, or by artificial means before being placed in storage.
• Curing may require 2 to 4 weeks, depending on weather conditions. In high humidity and wet regions, Onions are generally removed from the field for curing.
• To ensure that you are marketing a high-quality product, grade Onions by size and color and test them for insect damage.
• Onions that are maintained at 32°F and 65 to 70 percent relative humidity can be stored for approximately 1 to 8 months, depending on the variety.

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