2. Planting in spring and autumn; Protected areas can be planted all year round except in summer; Shading nets can be planted in summer in northern mountainous areas such as Yanqing, Huairou and Miyun. Generally, it is harvested 60-80 days after sowing, and can be harvested one after another 30 days after transplanting.
3. No matter sowing or transplanting, we should carefully prepare the soil and apply sufficient base fertilizer. Apply decomposed, finely divided organic fertilizer or expanded decomposed chicken manure.
4. It can be transplanted 40-50 days after sowing. Plant a hole every 8- 10 plant, the row spacing is 12-20cm, and the hole spacing is 8- 10cm, which should be shallow but not deep, and water the planting in time. It can also be harvested directly without transplanting after sowing.
5. Before and after emergence and after transplanting, the soil can't be dry, so it's advisable to irrigate with small water frequently, control watering after 1-3 seedling stage and transplanting slowly, and intertillage 1-2 times to promote root growth, generally watering once every 7- 10 days. If the basal fertilizer is applied less, or the harvest period is too long, the top dressing should be 1-2 times, the decomposed expanded chicken manure should be applied, and the root system should be cultivated 1-2 times in the later stage. In summer, the temperature is high and the light is strong, so it is necessary to build scaffolding to cover the sunshade net.
Extended data
cultivation techniques
1, planting period
The planting period of onion is not strict, and it can be planted from early June to early July.
2, fine soil preparation, sufficient base fertilizer.
Choose plots with high and dry terrain, deep soil layer, convenient irrigation and drainage and fertile soil for planting. Before ploughing, 4,000 kg of fully decomposed farm manure should be spread or furrowed before planting, and urea 15 kg, 20 kg of calcium superphosphate or 20 kg of compound fertilizer should be mixed into the farm manure in advance, and then deep ploughing and harrowing should be carried out, furrowing and ridging should be carried out.
3. Strictly select seedlings and plant them early.
Water once two days before emergence to ensure that the seedlings are dry and wet properly. When seedlings emerge, diseased and residual seedlings should be eliminated, and strong seedlings should be planted in different grades.
4. Reasonable colonization
The row spacing is 80 cm, the plant spacing is 3-4 cm, and it is appropriate to plant 20-30 thousand plants per mu.
5. Planting method
Generally, the method of arranging onions and inserting onions is adopted. Chopped onions are suitable for short white onions, and inserted onions are suitable for long white onions. The principle of uneven planting depth should be mastered, that is, the heart leaves of onion seedlings should be 7- 10 cm higher than the ditch surface.
control of insect
Onion thrips
1, onion thrips are also called tobacco thrips and cotton thrips. It is one of the main pests that harm Liliaceae vegetables such as green onions, onions, garlic, leeks and crops such as tobacco and cotton, and it occurs everywhere every year.
2. Onion thrips mainly harm the heart leaves, buds and young leaves of the host, and both adults and nymphs can do harm. At the beginning of the disease, needle spots appeared on the epidermis of heart leaves and buds, and silver-white strip spots formed after the disease. When the pest is serious, the leaves will be twisted, yellow and withered, which will seriously affect the yield and quality of onion. The peak of this disease is from late May to mid-June.
3, prevention and control methods
(1) After the previous crop is harvested, the diseased leaves should be removed in time to reduce the source of the disease.
(2) Strengthen field management, water and topdressing in time to promote plant growth and improve its ability to resist pests and diseases.
(3) After onset, 80% dichlorvos EC 1000 times, Aphidine 2000 times, dimethoate EC 1000 times, and phoxim emulsion 50% 1500 times, once a week, for a total of 2-0 times.
References:
Baidu encyclopedia-onion