Technical points of raising seedlings of onions

First, choose the superior species. In the onion producing areas of central and southern Hebei Province, vegetable farmers can choose early-maturing red-skinned onion varieties, such as Zixing, Ziyu, Ziyan and other varieties. These varieties are highly spicy, high output, excellent quality, best-selling exports, and are favored by foreign merchants. Generally, the yield per mu is about 5000 kg, and the high yield can reach more than 7500 kg.

Second, prepare the seedbed. The nursery bed should choose the land with loose and fertile soil, strong water retention and no spring onions and garlic vegetables in 2-3 years. Each mu of field requires a seedbed area of about 35 square meters, with a general seed consumption of 0.5 kg. Before sowing, 1000 kilograms of fully mature farm manure should be applied, and then 20-30 kilograms of compound fertilizer should be applied, and then ploughing and fine soil preparation should be made into a 1.5-meter-wide bed, which should be watered thoroughly for sowing.

Third, sowing seeds at the right time. The time of sowing directly affects the size of seedlings, which ultimately affects the yield and benefit of onions. The growth period of early sowing seedlings is prolonged, resulting in oversized seedlings and easy bolting, while late sowing seedlings are weak, low cold tolerance and easy to die in winter. Therefore, in order to achieve high yield, we must master the best sowing time. According to experience, in the central and southern part of our province, the most suitable sowing time is 3 days before and after White Dew. Dry seed sowing is often used to cover fine soil after sowing, and it is appropriate to see no seeds. After covering the soil, 33% of the herbicide per mu of the seedbed can be sprayed with 100ml spray to prevent weeds in the seedbed.

Fourth, seedling management. The center of seedling management is to cultivate strong seedlings. After sowing, cover a layer of wheat straw or shade net on the border surface, which is conducive to moisturizing, high temperature and rain protection. The soil should always be kept moist before emergence. When about 60% of the seedlings grow on the seedling bed, the mulch can be removed and sprinkled in time according to the weather conditions. Prevent seedling bed hardening, and can be combined with watering 1% urea, through fertilizer and water control to cultivate strong seedlings of the right age. It is not only necessary to prevent the seedlings from growing too large, causing early bolting, but also to avoid the weak growth of the seedlings and affect the overwintering. In general, onion seedlings can be planted when they reach 4 true leaves, the plant height is 20cm, and the leaf sheath diameter is 6mm.

Fifth, planting at the right time. When planting, the onion seedlings should be transplanted separately according to the size of the onion seedlings so that their growth is consistent, and the large seedlings with a leaf sheath diameter of more than 8 mm and weak seedlings and diseased seedlings with a diameter of less than 3 mm should be removed. The colonization is generally completed from the end of October to the first ten days of November, and the daily average temperature is 4 ℃ ~ 5 ℃. Since onion takes about 30 days from planting to resuming growth, it is necessary to promote its root system to grow well and prevent dead seedlings caused by soil freezing before the severe cold. The planting density is generally about 20,000 plants per mu, with a row spacing of 20 cm and a plant spacing of 15 cm. The planting depth is better without burying heart leaves (that is, farmers commonly known as "pentagonal strands"). After planting, pour water thoroughly to promote the survival of onion seedlings, avoid flooding in the field, so as not to cause soil consolidation.