Efficient Seedling-raising techniques of vegetables

3. Management of sub-seedbed: The growth time of seedlings in sub-seedbed is long, and it can be generally divided into three periods for management.

① seedling stage: after seedling division, the seedling root system is damaged to a certain extent and needs 4~7D to recover, which is called seedling stage. During this period, it is necessary to maintain a higher bed temperature in management, and strive to keep the ground temperature at 18~22℃, the temperature at 25~30℃ during the day and 20℃ at night. At the same time, it is necessary to close the shed and basically not ventilate to maintain a high air humidity, reduce plant transpiration, prevent seedlings from losing too much water and wilting seriously, thus promoting wound healing and new root formation.

2 vigorous growth period: this period of seedling growth, rapid growth rate, rapid growth of leaf area, vegetative growth and reproductive growth at the same time. In the management to provide appropriate temperature, strong light, adequate water and nutrients, and reflect the promotion of control, promote steady growth. After the seedlings resume growth, the temperature control index should be slightly lower than that of the seedling stage, generally the temperature should be reduced by 4~5℃, and the ground temperature should be reduced by about 2℃. And more ventilation to see the light, improve the photosynthetic efficiency of seedlings, but also to ensure the supply of water and nutrients. In normal sunny weather, 2~3D watering once, rainy weather 4~5d watering once, strictly prevent bed soil "white". Watering should be combined with topdressing, available 0,2% NPK compound fertilizer and about 30% decomposed human excrement pouring.

③ Seedling training: In order to improve the adaptability of seedlings to the environment after planting and shorten the time of slow seedlings after planting, seedlings should be trained about one week before planting. Specific measures include:

◆ Reduce bed temperature: The temperature can be reduced to 18~20℃ during the day and 13~15℃ at night.

◆ Water control: The seedling stage is generally no longer watered, and the bed soil is "exposed".

◆ Uncovering the film ventilation: at the beginning of the seedling training, first remove part of the film; with the extension of the seedling training time, it should be gradually uncovered until the film is completely uncovered, so that it can fully adapt to the open field environment.

◆ Field with medicine: 2-3 days before planting, medicine should be applied once to prevent disease and field with insects.