Thaw the soil in early spring, sow seedlings directly as soon as possible, choose bulbs with a diameter of more than 3cm in summer, store them for wintering, and sow and harvest them in the next year.
It takes about 16- 19 months from sowing to harvesting, which shortens the seed collection cycle and reduces the cost. It can be used in breeding and production, but without the selection of mature bulb traits, the seed traits have deteriorated.
Extended data:
Onion is a long-day crop, which needs more than 14 hours of long-day sunshine during bulb expansion and bolting flowering. Under the condition of high temperature and short sunshine, only leaves grow and onions cannot form.
Onion should get sufficient water supply during germination, seedling growth and bulb expansion. However, water should be controlled at seedling stage and before overwintering to prevent seedlings from growing white and suffering from freezing injury.
Irrigation should be controlled before harvest 12 weeks to enrich bulb tissue, accelerate maturity and prevent bulb cracking. Onion leaves are drought-tolerant, suitable for 60% ~ 70% humidity, and diseases are easy to occur if the air humidity is too high.
References:
Onion-Baidu Encyclopedia