First, the onion is cold-resistant vegetables, long growth period, requiring long days and high temperature conditions. Onion seedlings grow slowly, occupy a long time, and generally adopt seedling transplanting in production. Therefore, the cultivation of age-appropriate seedlings is the key to the high yield of onions. The criteria for strong seedlings are: about 50 days of seedling age, 20-25 cm of seedling height, 4 to 5 leaves, and 0.6 to 0.8 cm thick stems. The roots are well developed and free of pests and diseases. Henan Province can choose short-day varieties of summer crops. Under normal circumstances, the open field planting is planted in the middle and early September, and the greenhouse is planted in late March.
Second, the seedbed preparation onion seedling nursery bed site selection within three years did not plant onion and garlic vegetables can be poured into the dry canopy can be ranked flat, loose texture, fertility above average neutral or slightly acidic soil. Sand soil, clay soil, alkaline soil and low-lying land are not suitable for seedbeds. 10 to 15 days prior to sowing, clean the pastoral land, plough the land, combine the deep-rooted farmyard manure into a base fertilizer, apply 2,000 to 3,000 kilograms of farmyard fertilizer and 20 kilograms of superphosphate per 667 square meters, and then plough the land. The machine is made of flat trenches, which are 1 to 1.2 meters wide and 20 to 25 meters long.
3. Before Seed Processing Seed Onion The onion seeds are soaked in formalin 300 times for 3 hours, rinsed with water, dried after sowing, or soaked in warm water at 50°C for 25 minutes, then placed in cold water to cool and dry After sowing.
Fourth, sowing in order to speed up the emergence, onion seeds can be soaked germination, specific methods are as follows: The seeds soaked in cold water for about 12 hours, remove and wrap with a damp cloth, germination at 20 ~ 22 °C, rinse with water every day 2 This time, when most of the seeds are white, they can be sown. Under normal circumstances, the ratio of seedling nursery area to planted field area is 1:10~12, and the seeding rate per 667 square meters of seedbed is 2.5~3kg.
V. Seedling management The purpose of seedling management at the seedling stage is to cultivate age-appropriate seedlings, not only to prevent seedlings from growing too large and to bolt in advance, but also to avoid delicate seedlings that affect the progress and quality of transplanting. To achieve this goal, the growth of seedlings can be controlled by controlling the water and fertilizers, so as to achieve the age-matching standard.
1. Fertilizer and Water Management: Watering according to soil moisture, keep soil moist after emergence, and stop watering before planting; when the seedling grows to 10-15 cm high, topdressing nitrogen fertilizer or compound fertilizer to cultivate strong seedlings.
2. Temperature management: The emergence period of onion is 10 to 15 days, and the daytime temperature in the greenhouse is maintained at 20~30°C and 15°C at night. After the seedlings are in full bloom, they must be cooled to prevent seedlings from growing indefinitely. The daytime temperature should not exceed 20°C and nighttime should not be less than 5°C.
3. Ventilation: When the seedlings grow to 3 to 4 centimeters in height, the ventilation volume can be gradually increased. Ventilation is strengthened 7 to 10 days before planting. The soil moisture of the seedbed should be kept between 60% and 80%. If it is less than 60%, the water should be replenished.
4. Weed removal: Weeds were removed once every 15 days throughout the seedling period to ensure normal growth of onion seedlings.
6. Colonization When the age of onion reaches 50 to 60 days, it can be transplanted and planted.
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