Cultivation technology of heading lettuce

1. Selection of sowing period The heading lettuce prefers low humidity and cold environment. The fall cultivation period is from late September to mid November. Seedlings can also be raised in the protected area in early spring and planted in late April to mid-May.

2. Sowing and seedling first soak the seeds for a few minutes, then wrap them with a damp cloth, pay attention to aeration, and germinate in the 15-20 ℃ environment. After 2-3 days germination, you can sow. The nutrient cup seedling method uses a small amount of seeds, has a high survival rate and strong seedlings, and keeps the root system intact during planting. The formula of nutrient cup nursery soil is 6 parts of soil, 3 parts of compost, 1 part of chaff (or vermiculite), and a small amount of borax is added, and mixed into the cup. Sow 2-3 seeds per cup. Cover one layer of thin soil after sowing, cover with straw, and drown enough water. In addition, some areas use plug trays to raise seedlings, and the seedling formation effect is also very good.

3. Management of seedling stage: 2-3 days after sowing, the straw can be removed, and it is not easy to produce tall seedlings in time. In the summer, seeding and seedlings should be set up in a shaded shed, which can protect against rain and shade. After emergence, sprinkle water every morning and night. About 2 weeks after sowing, thin seedlings are removed, and weak and tall seedlings are removed, and a strong seedling is retained. 15 days after seedling age, thin urea can be applied. Generally 25-30 days of seedling stage.

4. Site preparation and planting Before planting, prepare the site carefully, apply enough base fertilizer to loosen the soil layer, so as to facilitate the growth of the root system and the absorption of fertilizer and water by the roots. Early maturing species are planted in two rows, with a row spacing of 35 cm, plant spacing of 25-30 cm, and acres of 4000-5000 plants. Mid- and late-maturing species are properly sparsely planted for adequate growth. It can be cultivated with high indica, with row spacing of 40 cm, plant spacing of 30-35 cm, and 3000-3700 plants per mu. After 3-4 days of planting, water in the morning and evening every day to increase the survival rate. If the lack of plants is found, seedlings should be replenished in time.

5. Field management The growth period of lettuce is longer, and it must be topdressed several times, usually once every 7-10 days. 4-6 days after planting, apply thin-film quick-acting nitrogen fertilizer to promote hair root and leaf growth. When you start filling, add potassium fertilizer. Before the plants are sealed, heavy fertilizer should be applied. 20 kg of compound fertilizer per acre plus 7.5 kg of potassium chloride can be applied in shallow trenches between the two rows, and then covered with soil to avoid the fertilizer contacting the root system. Irrigation or watering can be used to keep the soil moist. In the rosette stage, moisture must be strictly controlled to prevent disease. During the balling period, avoid water in the area or plant contact with water, so do not use water spray or sprinkler irrigation. You can use "horse race" furrow irrigation or water between rows. Water control should be carried out 15 days before harvest. The root system of the heading lettuce is shallow, and the mid-cultivation should not be too deep, so as not to damage the root system. The mid-cultivation should be carried out before the plants are sealed. When large-scale lettuce is cultivated in Japan, the black mulch method is adopted, which has a good effect on cooling and moisturizing, preventing the loss of fertilizer and weeds.

6. Picking lettuce from planting to harvest, early maturing is about 55 days, middle maturing is about 65 days, and late maturing is 75-85 days. But it is better to harvest a few days in advance. The harvesting standard can be pressed obliquely from both sides of the leaf ball with both hands, and it is advisable to feel firm and not loose. Control water 15 days before harvest. When harvesting, choose plants with tight leaf balls to cut from the ground, strip old leaves, leave 3-4 outer leaves to protect the leaf balls, or strip all the outer leaves, use polystyrene film for single-ball packaging, and transfer in time The refrigerated cars are shipped out for sale, and the suitable temperature for storage and storage is 1-5 ° C.

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