Onion Production Techniques: Cultivation, Pest Management, Harvesting, and Storage

Study Notes

Onion Production

Cultivation Techniques

Onion production involves several stages, starting with a suitable site selection. The ideal conditions for growing onions include loose, friable soils with a pH range of 5.8 to 6.6. Sandy loam and muck soils are commonly used for onion production. The different types of onions include long-day, intermediate-day, sweet Spanish, leeks, chives, and shallots. While the common dry onion (Allium cepa) is mostly grown, related species like garlic, leek, and chives are also included in onion production.

Pest and Disease Management

Effective pest and disease management strategies are crucial for successful onion production. Common pests affecting onion fields include thrips, aphids, leafminers, cutworms, and spider mites. Chemical control measures involve the use of pesticides such as azadirachtin, spinosad, and permethrin. However, the widespread availability of resistant strains of these pests necessitates the adoption of integrated pest management (IPM) approaches. IPM combines biological, cultural, and chemical practices to maintain onion yields while minimizing environmental impacts.

Diseases affecting onions include bacterial soft rot, fusarium wilt, and pink root. Prevention measures include crop rotation, crop debris elimination, deep plowing, and resistant variety selection. Additionally, biofungicide applications containing Bacillus amyloliquefaciens strain WL14 can help manage fusarium wilt.

Harvesting Methods

Onion harvesting typically occurs when the neck of the bulb falls onto the ground, indicating maturity. At this point, the leaves begin to turn brown and remain intact when bent. Manual harvesting is the most common method, although other tools like diggers and trowels can also be utilized. Ideally, onions should be harvested in the morning, avoiding rainy weather, which can cause bruises and mechanical damage.

Storage Practices

After harvesting, onions need to be properly stored to prevent spoilage. Traditional methods include spreading on the ground, storing in polyester plastic bags, or placing in wooden boxes or trays. For longer storage periods, temperatures below 7°C and humidity below 85% are recommended. Cold storage facilities are particularly effective in preserving onion quality. It is essential to ventilate the storage area to avoid anaerobic respiration, which can lead to premature sprouting.