Most varieties of onion (onion) in Heze, Shandong Province were sown in the open field in early September, and the seedling raising period was about 40 ~ 50 days.

Sowing time analysis:

Due to the different climatic conditions in different places, the suitable sowing date is not the same.

Most onion varieties in Shandong province were sown in the open field in early September, and the seedling raising period was about 40 ~ 50 days.

Seeding too early, the seedlings grow very big before winter, and bolting is easy in the second year, which consumes nutrients and reduces yield and quality.

Sowing late, small seedlings, poor root growth, easy to freeze to death in cold winter.

The suitable planting period is from the middle and late June 65438+1October to1early October165438+1October. Before planting, the seedlings have 3-5 leaves, plant height 15-20 cm, and pseudostem diameter 0.5-0.7 cm, which is the suitable seedling age.

Because onion likes cold environmental conditions and has strong frost resistance, its seedlings can withstand the low temperature of -7℃. When the temperature exceeds 26℃, the onion goes into dormancy.

Leaves will die at 30℃.

The low temperature period required for onion bud differentiation varies with varieties. Common varieties can survive vernalization in 50 ~ 60 days at 2 ~ 5℃.

It takes a short time for big seedlings to undergo vernalization, and a long time for small seedlings. If the seedlings are too small, it is difficult to pass vernalization.

Therefore, some varieties are easy to bolting, and some varieties are not easy to bolting. .

Planting method of onion

I. Variety selection and land use. Qinghai province is a high latitude area, so long-day varieties should be selected. The varieties used should be selected according to the climatic and environmental conditions and cultivation habits, and the American hybrid variety "Bailuoke" can be selected. This variety has the characteristics of big pile, pure white color, disease resistance and high quality, and other varieties such as "Red Lantern" can also be selected. The main exporter of onion in China is Japanese. Cultivated land should be selected in Sichuan-water area with good soil fertility, flat terrain and good water and heat resources.

Second, sowing and seedling raising

1, timely sowing. Onion sowing is generally around beginning of autumn, and the method can be drilling or broadcasting, which requires even sowing. The seed consumption per hectare is about 1.8-2.25kg (depending on the germination rate), and each hectare of seedbed can provide about 15 hectares of transplanted seedlings.

2. Seedling management. The appearance time of onion is about 7- 10 days. When most onions appear, they should be irrigated according to the water content. After the two leaves grow out, urea105-108kg/ha can be applied together with intertillage weeding, and then irrigation can be performed. Generally, water should be poured every 10 day/time.

3, onion seedlings follow in. In the middle of June, the seedlings were raised for 5438+065438+ 10. The onion seedlings with the same seedling quality were tied into small bundles, the rootless and short seedlings were removed, and the tied onions were placed in the shade. After one row was full, the soil was moistened from the base of the onion seedlings to the middle and upper parts, and the second row was tied in for the winter.

4. Soil treatment. In the second year, onion planting plots should be treated with chemical soil before winter, and winter water should be thoroughly irrigated. For soil treatment of underground pests, 3750-6000 ml of phoxim EC can be sprayed on the ground per hectare (it should be carried out in the evening because it is easily decomposed by light) and turned into the soil evenly, or 22.5-33.75 tons of 5% phorate granules can be applied evenly. Weedy soil can be treated by spraying 2250 ml herbicide or 48% trifluralin, 2250-3000 ml acetochlor or 1875-2250 ml cauliflower per hectare and turning it into the soil evenly.

Third, adequate basal fertilizer and reasonable close planting. The root system of onion is a fibrous root system composed of string adventitious roots. The root system is underdeveloped and weak, and the root groups are mainly concentrated in the soil with a depth of 20 cm. The ability of absorbing fertilizer and water is weak, and the requirements for soil are high. Onions are not suitable for continuous cropping, and they are usually rotated once every three years.

1, soil preparation and fertilization. When preparing the soil, deep ploughing should be done, the ploughing depth should be not less than 20 cm, and the plot should be flat, which is convenient for small water irrigation (flood irrigation) without water accumulation, and the soil preparation should be very fine. Generally, 30 cubic meters of high-quality decomposed organic fertilizer, 450-600 kilograms of diammonium and phosphorus-potassium compound fertilizer are applied per hectare, and the fields with moderate fertility (dry stubble such as bean stubble and corn are better). The planting method should be flat, with a width of 0.9- 1.2m (depending on the width of plastic film) and a trench width of 0.4m, which is convenient for operation.

2. Plastic film mulching. Plastic film mulching can increase ground temperature and yield. Irrigation should be carried out on the plot before film mulching. After the soil is slightly dry, the film mulching should be harrowed to keep moisture, and the edge of the film pressing should be tight. Before planting, drill holes according to the row spacing of 20cm× 15cm. Punching can be done by yourself, and 12 holes can be made at a time.

Step 3 plant. In February of the following year, onions can be planted when the topsoil melts about 5 cm, and the planting depth is subject to no burying of heart leaves and no dropping of seedlings, and watering is subject to no dropping of seedlings and no accumulation of water at the border. The seedlings should be straight and shallow (about 2 cm), and the roots should be closely combined with the soil. If planted too deep, it will easily affect the expansion of bulbs. Onions enter the slow seedling stage after planting, where conditions permit, they can be watered with planting water, and then watered when new leaves grow after slow seedling.

4. Reasonable close planting. Density is an important factor in yield. Onion has few leaves and strong upright, which is suitable for close planting. The experiment shows that reasonable close planting can improve the yield per unit area of onion, and the planting density depends on the variety characteristics, soil conditions and production objectives. Generally, there are 330,000-600,000 medium-mature varieties per hectare. If the row spacing is 20cm× 15cm, 495,000 plants will be planted per hectare.

Fourth, on-site management. After planting, the relative humidity of soil should be kept at 60-80%. If it is lower than 60%, it needs water, which is limited to dry soil. Topdressing water also depends on seedling conditions and soil fertility, and generally it is necessary to "irrigate small water frequently". Fertilizer and water management should master the principle of "control before the year, promote after the year", and topdressing should be carried out in addition to base fertilizer during the growing period to ensure the growth of seedlings. For plots with poor fertility, combined with watering, urea 105- 150kg can be applied per hectare.

1, leaf vigorous growth period. Onion enters the vigorous growth period when the leaves are 6 1. At this time, the fertilizer demand is large, and 300 kilograms of urea and 300 kilograms of 48% nitrogen, phosphorus and potassium compound fertilizer can be sprayed on each hectare of film surface, which can meet the nutrient demand of onion in the vigorous growth period.

2. Bulb expansion period. When the above-ground part of onion reaches 9 leaves, it enters the stage of bulb expansion, the plant no longer grows, the assimilate of leaves is transferred to the bulb, and the bulb expands rapidly. This stage is another peak of fertilizer demand, especially for phosphorus and potassium fertilizer. Practice has proved that the normal expansion of bulbs can be ensured by applying 450 kg 48% NPK compound fertilizer per hectare.

3. Pest control. Onions are prone to downy mildew, purple spot and rust, and the downy mildew and purple spot are more serious in rainy and humid weather. Downy mildew and purple spots can be sprayed with 600 times solution of 75% chlorothalonil or 500 times solution of 64% antiviral alum; 600 times of 25% virulent bacteria or 65% mancozeb can also be sprayed. Spraying 15% triadimefon 1500-2000 times, every 10- 15 days, 3-5 times in a row to prevent rust. The interval between the last use of the above pesticides and the harvest period should be 7- 10 day. 800 times of 40% omethoate or 300g/ha of 10% imidacloprid can be sprayed to control garlic thrips. These two pesticides are only allowed to be used once in the growth period, and the interval between them and the harvest period should be greater than 15 days.

Fifth, timely harvest

1. Before harvesting, spraying 500 mg/kg of fresh blue element (MH) on leaves can prevent germination during storage.

2. Don't water the onion 7- 10 days before harvesting, so as to avoid that the onion absorbs enough water in the ground and can't stand storage.

3. The best harvest time is after the tubular leaves above ground naturally lodging 30%. At this time, the first and second leaves at the base of the plant are yellow, the third and fourth leaves are still green, the pseudostem is dehydrated and soft, and the aboveground part naturally lodging. Harvesting should be done on a sunny day. Pull out the roots of main plants and dry them in the field for 1-2 days. When drying, the onion is covered with leaves, only the leaves are dried, and the yield per hectare is 60-90t. In order to improve the commodity rate, the market in the morning can also be harvested in advance.