Cultivation technology of head lettuce

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

2. Sowing seedlings, soak the seeds for a few minutes, then wrap them with a damp cloth, pay attention to aeration, put them in a 15-20℃ environment to germinate, and germinate after 2-3 days before sowing. The nutrient cup nursery method uses less seeds, the seedling survival rate is high, the seedlings are strong, and the root system is kept intact during the planting, and the plant grows fast after planting and the heart is early. The nutrient cup nursery soil formula is 6 parts of soil, 3 parts of compost, 1 part of chaff (or vermiculite), and a small amount of borax is added, mixed well and put into the cup. Sow 2-3 seeds per cup. After sowing, cover with a layer of thin soil, and then cover with straw, soak the water. In addition, some areas use plug trays to raise seedlings, and the effect of growing seedlings is also very good.

3. Seedling management The sprouting can be peeled off 2-3 days after sowing, and it is easy to produce tall seedlings if the grass is not timely released. In summer, when planting seedlings, it is necessary to build a shade shed, which can prevent the impact of rain and shade. After emergence, water every morning and evening. About 2 weeks after sowing, thin seedlings were removed. Weak seedlings and high-footed seedlings were removed, and a strong seedling was retained. After 15 days of seedling age, thin urea can be applied. The general seedling period is 25-30 days.

4. Site preparation and planting Carefully prepare the site before planting and apply sufficient base fertilizer to loosen the soil layer to facilitate root growth and fibrous roots to absorb fertilizer and water. Early maturity seeds are planted in two rows, with a row spacing of 35 cm, a plant spacing of 25-30 cm, and 4000-5000 plants per mu. Medium-mature and late-mature seeds are properly thinned to allow full growth. It can be cultivated with high borders, with a row spacing of 40 cm, a plant spacing of 30-35 cm, and 3000-3700 plants per mu. 3-4 days after planting, water every day in the morning and evening to increase survival rate. If a missing plant is found, the seedlings should be replenished in time.

5. Field management of lettuce heads grows for a long period of time. It needs to be topdressed several times, usually once every 7-10 days. 4-6 days after planting, a thin nitrogen fertilizer is applied thinly to promote hair root and leaf growth. Potassium fertilizer should be added when starting to be confident. Before the plants are sealed, heavy fertilizer should be applied. Use 20 kg of compound fertilizer per acre and 7.5 kg of potassium chloride, which can be applied in shallow trenches between the two rows, and then covered with soil to avoid the fertilizer from contacting the root system. It can be irrigated or irrigated from the planting to the beginning of the heart (rose stage) to keep the soil moist. When entering the rosette period, we must strictly control the moisture to avoid the occurrence of diseases. During the heading period, the area water or plants are not exposed to water, so it is not possible to use water spraying or sprinkler irrigation. You can use "horse race" ditch irrigation or spray water between the rows. Water control should be carried out 15 days before harvest. The root system of head lettuce is shallow, and the mid-tillage should not be too deep to avoid damage to the root system. Mid-tillage should be carried out before the plants are sealed. When cultivating head lettuce in a large area in Japan, the black mulch method is used to cool and moisturize, prevent fertilizer loss and weeds.

6. Harvest and lettuce from planting to harvest, early maturing seeds about 55 days, medium maturing seeds about 65 days, late maturing seeds 75-85 days. But it is better to harvest a few days in advance. The harvesting standard can be pressed diagonally from both sides of the leaf ball with two hands, which should be firm and not loose. Water control 15 days before harvest. When harvesting, choose plants with tightly condensed bulbs to cut off the ground, strip off the old leaves, leave 3-4 outer leaves to protect the bulbs, or strip all outer leaves, use polystyrene film for single-ball packaging, and transfer in time The refrigerated carriages are shipped out for sale, and the suitable temperature for transportation and storage is 1-5℃.

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