Onion cultivation technology in open field in autumn and winter

Onion is not only a good fine vegetable, but also has a high health value. Some developed countries also use onion for pharmaceuticals, and it can play a role in preventing cancer and cardiovascular diseases. According to the characteristics of onion growth and development, in order to obtain high yield and high efficiency in production, the following points should be mastered in cultivation technology.

1. Variety and land selection. Qinghai Province is a high-latitude region, and long-day sunshine varieties should be selected. The variety used should be selected according to climatic and environmental conditions and cultivation habits, and the American hybrid variety "White Rock" can be selected. This variety has the characteristics of large, tall piles, pure white color, good disease resistance, etc., and other varieties such as "red lantern" can also be selected. China's main exporter of onions is Japan. Cultivated land should be selected in Sichuan and Sichuan areas with good soil strength, flat terrain and good water and heat resources.

Second, sowing seedlings

1. Timely sowing. Onion seeding is generally around the beginning of autumn. The method can be seeded or spread. It requires uniform seeding. The amount of seed per hectare is about 1.8-2.25 kilograms (according to the germination rate, which can be increased or decreased as appropriate). The seedbed per hectare can be used for transplanting seedlings of about 15 hectares.

2. Seedling management. The onion emergence period is about 7-10 days. When most of the onion emerges, it will be irrigated according to the condition. After growing 2 leaves, it can be combined with cultivating barnyard grass to apply 105-108 kg / ha of urea, and then irrigate. Water is usually irrigated every 10 days.

3. Fake onion seedlings. Start seedlings in mid-November. Put the onion seedlings of the same seedlings into small handles, remove the rootless, too short young seedlings, place the lined onions in a row and place them in the shade. Yong to wet soil from the base to the upper middle, and then set up a second row of false wet soil to overwinter.

4. Soil treatment. In the following year, the onion plantation site should be treated with underground soil pests and weeds before winter, and drenched with winter water. For soil treatment of underground pests, 3750-6000 ml of phoxim emulsifiable concentrate can be sprayed per hectare on the ground (because of its visible light decomposition, it should be carried out in the evening), and evenly turned into the soil, or 5% methyl phosphate mixed granules 22.5-33.75 Tons are evenly applied into the soil. Weed soil treatment can be sprayed with field herbicides or 48% fluroxyline 2250 ml per hectare, or 50% acetochlor 2250-3000 ml or caocaotong 1875-2250 ml, and evenly spread into the soil .

3. Apply sufficient basal fertilizers and plant them reasonably. The root system of the onion is a fibrous root system composed of string-shaped adventitious roots. The root system is underdeveloped and weak. The root group is mainly concentrated in soil that is 20 cm deep. The ability to absorb fertilizer and water is weak, and it requires higher soil. Avoid continuous cropping of onions, usually once every 3 years.

1. Land preparation and fertilization. When preparing the land, plough deeply. The ploughing depth should not be less than 20 cm. The land should be level to facilitate small-water irrigation (diffuse irrigation) without water accumulation, and the land preparation must be very fine. Generally, medium-fertility fields (dry stubble such as soybean stubble and corn are better) apply 30 m3 of high-quality rotten organic fertilizer per hectare, and 450-600 kg of diammonium and phosphorus-potassium compound fertilizer are used as base fertilizer. The planting method should be flat loquat. The general loquat width is 0.9-1.2 meters (depending on the mulch film width), and the trench width is 0.4 meters for easy operation.

2. Lamination. Laminating can increase ground temperature and increase yield. Before mulching, irrigate the plot. After the soil is slightly dry, follow the rake and mulch to protect the mulch. After mulching, eyelets were planted at a row spacing of 20 cm x 15 cm before planting. The eye punch can be made by yourself, 12 eye punches at a time.

3. Colonization. In February of the following year, the onion can be planted when the surface soil melts about 5 cm. The depth of the planting is not buried, and the seedlings are not buried. Planting seedlings should be straight, shallow (about 2 cm), and the roots and soil should be tightly combined. If it is planted too deeply, it will easily affect the swelling of the bulb. After planting, the onion enters the slow seedling stage. Water can be planted in the place where conditions permit. When the seedlings are slowed down, new leaves will be watered.

4. Reasonable dense planting. Density is an important factor in yield. Onions have few leaves and strong uprightness, and are suitable for dense planting. Experiments show that reasonable dense planting can increase the yield per unit area of ​​onions, and the planting density depends on the characteristics of the variety, soil conditions, and production goals. Generally, mid-maturing varieties are 330,000 to 600,000 plants per hectare. If the distance between rows is 20 cm x 15 cm, 495,000 hectares will be planted.

Fourth, field management. The relative humidity of the soil after planting should be maintained at 60-80%. Below 60%, water is needed, and the soil is limited. Watering and topdressing should also depend on seedling conditions and soil fertility, and generally should be "small water diligent irrigation". Fertilizer and water management should grasp the principle of "controlling the year before and promoting the year after year". In addition to the base fertilizer during the growth period, topdressing must be performed to ensure the growth of seedlings. For poor land, 105-150 kg urea can be applied per hectare in combination with watering.

1. Ye Wangsheng's growing season. Onion 6 leaves and 1 heart will enter the vigorous growth period, at this time, a large amount of fertilizer is required. 300 kg of urea can be sprayed on the film surface and 300 kg of 48% nitrogen, phosphorus, potassium compound fertilizer can be added to meet the vigorous growth period of onions. Demand for nutrients.

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

3. Pest control. Onions are susceptible to downy mildew, purple spot, and rust. In rainy and wet weather, downy mildew and purple spot are more serious. Downy mildew and purple spot disease can be sprayed with 600 times liquid of 75% chlorothalonil or 500 times liquid of 64% antiseptic alum; it can also be sprayed and sprayed with 600 times liquid of 25% rufamycin or 65% mancozeb zinc. Rust control with 15% triazolone 1500-2000 times liquid spray, spray once every 10-15 days, spray 3-5 times. The last use of the above pesticides should be 7-10 days after the harvest time. Thrips onion can be controlled with 800% solution of 40% omethoate or 300 g / ha of 10% imidacloprid. These two pesticides are allowed to be used only once during the growing season and should be separated by more than 15 days from the harvest time.

Five, timely harvest

1. When the leaves are not withered before harvesting, spray the leaf surface with 500 mg of chlorophyllin (MH) to prevent germination during storage.

2. Stop watering 7-10 days before harvesting to prevent the onions from absorbing enough water when in the field and not resistant to storage.

3. The harvest period is 30% after the tube leaves in the ground are naturally lodged. At this time, the plant base *, the two leaves are yellow, the third and fourth leaves are green, the pseudostems are dehydrated and soft, and the ground is naturally lodged. Harvest should be carried out on a sunny day. The main plant is uprooted and air-dried in the field for 1-2 days. The onion is covered with leaves during the sun. Only the leaves are left without the sun. The yield per hectare is 60-90t. In order to improve the commodity rate, the market can also be harvested in advance in the morning.

The market requires a large bulb, crisp and tender texture, fine organization, and excellent quality. Order purchases are classified according to order requirements. Generally, the first-grade product has a transverse diameter of 8 cm or more, the second-grade product has a transverse diameter of 6-8 cm, and the defective product has a diameter of less than 6 cm. Leave the fake stems on the bulbs and cut them 1-1.5 cm. It is required that the shallots are intact, the surface is clean, and there is no disease and mildew spots, no mechanical damage, no dryness or softness.

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