Climate / Temperature: Onion plants thrive in warm and humid climates. Though primarily a rabi crop, onions can also be grown in the kharif season. It is important to sow the crop in a way that avoids rainfall during the harvesting period. Onions require minimal irrigation. Seeds germinate best at temperatures between 20°C to 25°C, while the bulbs develop optimally under long days and higher temperatures.

Water Demand: Onion crops require 400-700 mm of water. There should be no water shortage during seed sowing. Irrigation should be light and frequent, repeated every 7-13 days. Onion roots are set at a depth of 8-10 cm. Irrigation should stop 15-20 days before the bulbs mature completely.

Soil: Sandy loam soil with good drainage is ideal for onions. The soil should have sufficient fertility for better yield. The optimal pH range is 6.5 to 7.5. For soils with higher pH, add gypsum, and for lower pH soils, use lime.

Major Varieties:

Some key varieties of onions include:

• Agrifound Dark Red (Kharif)
• Agrifound Light Red (Rabi)
• Arka Pragati (for both seasons)
• N-53, Bhima Super, Bhima Red

Sowing of Crops:

Onions are sown in July-August for the kharif season and in December-January for the rabi season. Harvesting takes place in November-December for kharif and March-May for rabi. Maintain a row spacing of 10-15 cm between plants.

Suitable Time of Sowing:

• Kharif: July-August
• Rabi: December-January

Field Preparation: Deep plowing should be done to turn the soil. Level the field and create beds. Use organic manure like cow dung and compost. Irrigation should be done through drip or sprinkler systems.

Crop Cycle: The crop takes 4-5 months to mature. Onions should be harvested after the bulbs are fully developed and the leaves dry out. After harvesting, the onions should be sun-dried in the field.

Water Management: Onions require 5-8 irrigations in the kharif season and 12-15 irrigations in the rabi season. Crops sown later may need up to 12 irrigations.

Weed Management: Frequent irrigation and maintaining proper soil moisture will help manage weed growth. Mechanical weeding and the use of herbicides can also be implemented.

Harvesting: The crop is ready for harvest in 4-5 months. Bulbs should only be harvested after they have fully developed and the leaves have dried out. After harvesting, the bulbs should be dried in the field to prevent spoilage.

Diseases & Disease Prevention:

• Smudge disease: Spreads at 30-35°C and 80-90% humidity. Remove infected plants.
• Basal Rot: Caused by excess moisture at moderate temperatures. White fungal growth appears on the bulbs.
• Damping-off: Seeds rot and seedlings die due to excessive moisture. Use healthy seeds.
• Leaf spot: Appears due to fluctuating temperatures. Practice crop rotation.
• Thrips: These insects suck sap from the leaves, damaging the crop. Use neem-coated urea.
• Cutworm: Caused by a lack of irrigation. Use pheromone traps to control the pest.
• Aphid attack: Causes yellowing of leaves. Adopt crop rotation and remove infected bulbs.

Storage: Proper ventilation is essential for storing onions. The storage height should be between 90-150 cm. For storing 25 metric tons of onions, the storage area should be 4.5x6.0 meters.

This structured guide provides clear information about onion cultivation, covering essential aspects from climate requirements to storage conditions.