Onions have the characteristics of strong adaptability and storage resistance, therefore, they are cultivated in most parts of China, and their cultivation techniques are as follows:
<h1 class= "pgc-h-arrow-right" >, onion planting variety selection</h1>
When selecting varieties, we must choose varieties that are suitable for the light conditions in the region, and most of the long-day varieties are cultivated in the northern region; while the autumn and winter cultivation in the southern regions is mostly short-day varieties. This requires that when we introduce seeds, we must introduce seeds from areas close to our own latitude, and we cannot introduce seeds from areas with vast differences in latitude.
The varieties of onions can be divided into yellow-skinned onions, white-skinned onions and red-skinned onions according to the color of the outer skin, and different varieties have different characteristics, so onion farmers must combine local consumption habits and climatic characteristics to choose the onion varieties to be planted.
< h1 class = "pgc-h-arrow-right" > second, management during onion sowing and seedlings</h1>
1. Sowing time
Whether the choice of sowing period is suitable for the yield and quality of onions is extremely related, the minimum temperature in winter is below minus 20 °C in the northeast region, generally sown in late summer and early autumn, transplanted and colonized in the spring of the second year; north china central and southern China, east China, middle China mostly use autumn sowing, pre-winter transplanting and colonization; in South China, generally sown in late autumn. The following takes East China and Central China as an example to take the cultivation technology of onion.
2. Fertilize the land before sowing
Choose a field with fertile soil, convenient irrigation, and far from industrial waste, and apply the bottom fertilizer appropriately about a week before sowing the seedbed, and the amount of bottom fertilizer should not be too much to avoid excessive growth of seedlings. Each acre of seedbed to apply organic fertilizer about 2000kg, calcium superphosphate about 40kg, after sowing deep ploughing, the depth of ploughing is greater than 20cm, after the completion of ploughing, it is necessary to make furrows, the width of the furrow surface is about 1 meter, the distance between the ridge surfaces between the two furrow fields is also required, the ridge height is about 15 cm, the ridge width is about 20 cm, and after the raking is leveled, it is watered to make a good foundation for the germination of onion seeds.
3. Sowing
The amount of onion sowing and seed germination rate, colonization area, unit area of colonization of plants, etc. have a certain relationship, in the actual planting to consider the elimination of part, should add 20% more of the amount of seed, the general mu sowing amount is controlled at about 5kg, the seed can be sown in the way, after sowing with fine sand cover on the seed surface, the thickness of the cover is about 2cm. After sowing, a small arch is erected to maintain the temperature of the onion nursery.
4. Seedling management
After the onion is sown, before the seedlings are unearthed, the following management tasks should be done:
Temperature management: after sowing, it is kept at 20 °C ~ 25 °C during the day and 13 °C at night; when the onion seedlings are out, it is necessary to cool down appropriately to prevent the seedlings from growing, and maintain 15 °C ~ 20 °C during the day and 10 °C at night. When the onion grows above 15 cm, the small arch can be uncovered to allow the seedlings to adapt to natural temperature changes.
Water and fertilizer management: Water management at the seedling stage is extremely important, and soil moisture should be maintained at about 60%. Found that the seedbed is dry to be watered immediately to prevent soil panel knots from affecting seed germination and seedling emergence; fertilization at the seedling stage is the key to cultivating strong seedlings, and the application of farm manure supplemented by other inorganic fertilizers can basically meet the needs of seedling growth.
Weeding seedlings: When the seedlings emit 2 to 3 true leaves, it is necessary to weed in time and carry out inter-seedlings, and the inter-seedlings follow the principle of leaving the weak and leaving the strong, leaving the small and leaving the large, to ensure that the seedlings are uniform and prevent slow growth due to the over-dense seedlings.
< h1 class = "pgc-h-arrow-right" > three, the colonization of onions</h1>
Base fertilizer application before colonization is very important, the type and amount of fertilization have a great impact on onion growth and the size of the bulb, here to the onion farmer friends first introduce a small knowledge of onion growth.
1. The smoking characteristics of onions
After the onion bulb expands, it has the characteristics of early extraction, which not only causes the decline in onion production, but also seriously affects the quality of onion. There are two factors in the early extraction of onions: the first is the need for a certain low temperature, low temperature is the dominant factor inducing the differentiation of onion buds, most varieties can complete the vernalization after 40 to 70 days at a low temperature of 2 to 5 ° C, and begin to smoke out the flowers; the second factor is the size of the onion seedlings, if the thickness of the onion leaf sheath is greater than 0.6cm, after about 40 days or so, it can complete the springing and flowering.
From the above two factors, we can see that in order to obtain fat bulbs and achieve higher yields, we must not grow onions too vigorously before the winter freeze in North China, Central China and Northeast China.
2. Fertilize and prepare the land before colonization
In East China and Central China, in late autumn and early winter, you can transplant and colonize, and the fertilizer can not be applied too much before colonization, let alone nitrogen fertilizer, all in order to prevent onions from growing too vigorously before winter freezing. In addition, in order to adapt to the characteristics of the onion whisker-like root, the base fertilizer used must be fully decomposed, and manure ripening, shallow application and even sprinkling are the technical points of using base fertilizer. Since onions are shallow root crops, the root system is mainly concentrated in the soil layer of 20 to 30 cm deep, so when fertilizing the land, it is necessary to turn the soil deeply, and the depth is generally about 50 cm to ensure that the root system can grow easily.
3. Raise the ridge as a furrow
After the land is leveled, the work of making ridges can be carried out. In general, the width of each field is about 1.5 meters, and the height of the ridge is about 20 centimeters and the width of the ridge is about 25 centimeters.
4. Watering and laminating
The day before colonization, water the field once to ensure that there is enough water after the seedlings are colonized, and after the underwater infiltration, it is necessary to spray 1 herbicide, and then coat the film, and the film on both sides of the field should be tightened and compacted to ensure that the lamination can play a role in maintaining soil temperature and humidity.
5. Seedlings
In the late autumn and early winter in East China and Central China, when the onion seedlings grow to 3 to 4 leaves, they can be transplanted and colonized. When raising seedlings, it is required to use a seedling shovel or shovel to raise seedlings, and the seedlings that emerge are graded according to large, medium and small, and the standard of seedlings of moderate size is to have 3 to 4 true leaves, the height of the plant is about 30cm, the diameter of the leaf sheath is 6 to 7mm, and the weight of each plant is 4 to 6 grams, and then planted separately, which is convenient for later management.
6. Colonization
Because the onion plant is upright and the leaves have little shade, it is suitable for dense planting. Generally speaking, the row spacing of onion colonization is 15 to 18 cm, the plant spacing is 10 to 13 cm, and about 30,000 plants are planted per mu. The depth of colonization is based on burying small bulbs and not pouring the seedlings after watering.
15 days after onion colonization is the slow seedling period of the onion, after the slow seedling period, which seedlings grow vigorously and which seedlings do not survive has been seen very clearly, then you can take the method of supplementing seedlings to replace weak seedlings and dead seedlings with robust seedlings.
After the slow seedling period, the weather in the northern region of Our country gradually becomes cold, from this period until the spring before the green, the growth of onions is relatively slow, mainly in the accumulation of nutrients, in order to supply the growth of the root system, so this period is also called the squat seedling period by onion farmers, before the winter soil is frozen, it must be watered once, and after watering the frozen water, there is no need for other management.
Winter to spring, along with the spring warming, onions also quickly entered the rapid growth period, they began to grow roots and leaves, the absorption capacity of the plant increased, this time of fertilizer management should also keep up in time.
<h1 class = "pgc-h-arrow-right" > iv. Management of onion nutrient growth</h1>
After the spring comes, the onion enters a rapid growth period.
Water management: In general, when the soil temperature at a depth of 10cm is stable above 10 °C, it can be watered back to green water. Starting from the watering of the rejuvenation water, it is necessary to water once every 6 to 9 days according to the climate and soil quality.
Fertilizer management: After the onion returns to green, the plant enters the vigorous growth period of the leaves, and the application of some nitrogen fertilizer during this period can promote leaf growth, and urea 15 to 25 kg and potassium sulfate 15 to 20 kg can be applied per mu of land.
<h1 class= "pgc-h-arrow-right" >5, onion bulb expansion period management</h1>
The onion begins to expand from the leaf sheath to the time of harvest, which is called the expansion of the onion bulb. As temperatures rise and hours of sunshine increase, the nutrients accumulated by onions begin to be transported to the leaf sheath, making the leaf sheath expand day by day to form bulbs.
1. Water management during bulb expansion
During the bulb expansion period, the water demand gradually increases, so timely watering according to the climate and soil conditions is still the focus of management. During this period, watering is done every 5 to 7 days to keep the moisture content of the soil between 60% and 80%.
2. Topdressing at bulb expansion stage
Apply potassium sulfate fertilizer 5 to 10 kg and urea 10 to 15 kg per mu, and water in time after fertilization to promote the absorption of nutrients by onions. There are many onion farmers who tend to apply too much nitrogen fertilizer during the onion expansion period is not right, if too much nitrogen fertilizer is used, the onion will be greedy and prosperous and affect the development of the bulb.
3. Pest control
The onion expansion period is also a high incidence of diseases and insect pests, so when conducting field management, it is necessary to pay attention to the occurrence of various diseases and insect pests, and once the diseases and insect pests occur, the combination of physical, biological and chemical control should be taken in time to carry out comprehensive control to ensure the healthy growth of onion seedlings. Common diseases of onions are downy mildew and gray mold, and insect pests are mainly the harm of ground maggots.
Downy mildew: mainly harmful to onion leaves, initially, onion leaves will appear oval spots, these places will become lighter in color, yellowish green, gradually become gray-white, in the later stage, often lead to the onion leaves dry and die.
Onion downy mildew is a high incidence period when the temperature is between 15 ~ 20 ° C, if it is found that there is a downy mildew disease, you can spray aluminum acephosphonate, bacillus, downy mildew and other agents for prevention and control, every 7 to 10 days once, continuous spray 2 to 3 times.
Gray mold disease: When it occurs, the leaves are covered with white oval or nearly round spots, mostly developing downward from the tip of the leaf, and gradually connecting into pieces, so that the onion leaves curl and die. Gray mold is easy to circulate in the spring when the soil moisture is too large, and can be controlled by spraying carbendazim, methylthiopramine and other agents.
Ground maggots: the common name of the fly larvae, the maggots that harm the onion are the larvae of the gray ground fly, if there is a maggot hazard, it can be controlled by 40% octyl thiophosphate emulsion 1000 times liquid irrigation.
< h1 class = "pgc-h-arrow-right" >6, onion harvesting</h1>
The lodging of onion plants is a sign of harvest. When the leaves gradually wither and begin to lodging, the outermost layer of the onion bulb 1 to 3 scales begin to dry and shrink, like a film can be harvested. Harvesting should choose sunny weather, and the harvest period of onions in different regions varies greatly, so it should be determined according to the growth of onions.
In addition, it is also necessary to take into account the weather conditions at that time, it is best to have a few sunny days after harvesting, in order to dry, hold the onion plant with your hand when harvesting, gently lift the plant, the onion head is also brought out, in the harvesting process, you must be careful not to touch the onion, otherwise the onion wound infection will cause decay.
Harvested onions can not be rushed to transport, must be fully dried, the onion bulb skin becomes dry when it can be stacked, generally to dry for about 10 days, drying must avoid rain, and finally store or sell.
In recent years, the market demand for onions is getting bigger and bigger, onions have also become a characteristic industry in many places with strong adaptability, high yield, storage resistance, etc. If you want to grow onions well, you must also learn from experienced onion growers according to the actual situation in the local area to be able to better apply the experience to actual production.