Planting techniques of heading lettuce with fertile soil and organic fertilizer

Heading lettuce likes to be cold and avoid high temperature. Lettuce seeds can germinate at more than 4 ℃, and the optimum temperature for germination is 15-20 ℃. The seedlings can tolerate low temperature and grow healthily when the daily average temperature is 12 ℃. The optimum temperature for leaf bulb growth is 13-16 ℃. Although leaf lettuce has wide adaptability to soil, in order to obtain good leaf balls, heading lettuce must choose fertile loam or sandy loam. If the soil is sandy, barren and insufficient organic fertilizer, it is easy to cause a variety of physiological diseases.

Seedling raising of heading lettuce

First, varieties: choose more heat-resistant and early-maturing varieties, such as Emperor and Jingyou 1. If you want big leaf balls, you can choose Alpan medium-cooked lettuce varieties.

Second, cultivation techniques:

1. The choice of sowing time: heading lettuce likes low humidity and cool, and the autumn sowing time is from late September to mid-November. Seedlings can also be raised in the protected field in early spring and planted from late April to mid-May.

two。 Sowing and raising seedlings: first soak the lettuce seeds for a few minutes, wrap them in a wet cloth, pay attention to ventilation, put them in an environment of 15: 20 ℃, germinate in 2 to 3 days, and then sow. The method of raising seedlings with nutrition cup has the advantages of small amount of seeds, high survival rate, strong seedlings, intact root system, fast growth after planting and early capping. Nutrition cup seedling soil formula: 6 parts of soil, 3 parts of compost, 1 part of grain husk (or vermiculite), and add a small amount of borax, mix well and put into the cup. Sow 2-3 seeds per cup. Cover with a thin layer of soil after sowing, then cover with straw and sprinkle with enough water. In addition, in some areas, the effect of raising seedlings with acupoint plates is also good.

3. Seedling management: sprouting 2-3 days after sowing, the straw can be removed, the straw is not uncovered in time, and it is easy to produce tall seedlings. Sowing and raising seedlings in summer, it is necessary to build a shade shed, which can not only prevent the impact of Rain Water, but also shade. After emergence, water is drenched in the morning and evening every day. The seedlings were carried out about 2 weeks after sowing, the weak seedlings and high-footed seedlings were removed, and one strong seedling was retained. Dilute urea can be applied after 15 days of seedling age. Generally, the seedling stage is 25-30 days.

4. Soil preparation and planting: before planting, carefully prepare the soil and apply sufficient basic fertilizer to loosen the soil layer to facilitate the root growth of lettuce and the absorption of fertilizer and water by fibrous roots. Early-maturing species were planted in double rows, row spacing 35cm, plant spacing 25~30cm, planting 4000-5000 plants per mu; medium-maturing and late-maturing species were sparsely planted properly in order to fully grow. It can be cultivated with high border, row spacing 40cm, plant spacing 30~35cm, planting 3 000 to 3 700 plants per mu. Three to four days after planting, appropriate amount of water was watered in the morning and evening every day to improve the survival rate. If missing plants are found, seedlings should be replenished in time.

5. Field management: the growing period of heading lettuce is long, so it is necessary to apply fertilizer several times, usually once every 7 to 10 days. 4-6 days after planting, available nitrogen fertilizer was applied thinly to promote the root and leaf growth of lettuce. When you start to keep your heart, you should apply more potash fertilizer. Before the lettuce is closed, heavy fertilizer should be applied. 20 kg compound fertilizer plus 7.5 kg potassium chloride per mu can be applied in a shallow trench between the two rows, and then cover the soil to avoid fertilizer contact with the root system. Planting to the rosette stage, you can use irrigation or irrigation to keep the soil moist. When entering the rosette stage, moisture should be strictly controlled to avoid the occurrence of diseases. During the heading period, avoid border area water or lettuce contact with water, so do not sprinkle water or sprinkler irrigation, but use "horse-running" ditch irrigation or water between rows. Water control was carried out 15 days before harvest. The root system of heading lettuce is shallow, mid-tillage should not be too deep, so as not to damage the root system, and mid-tillage should be carried out before lettuce is closed. When lettuce is cultivated in a large area, the method of covering black plastic film is adopted, which has a good effect on cooling and moisturizing, preventing fertilizer loss and weeds.

6. Harvest: from planting to harvest, early-maturing, middle-maturing and late-maturing lettuce took about 55 days, 65 days and 75-85 days respectively. But it is better to harvest a few days in advance. According to the harvest standard, press obliquely from both sides of the leaf ball with both hands, and it is appropriate to feel firm and not loose. Control water 15 days before harvest. When harvesting, the lettuce with compact leaf ball was cut from the ground, the old leaves were removed, 3-4 outer leaves were left to protect the outer leaves, or all the outer leaves were stripped, packed with polystyrene film, and transferred to the refrigerated car in time for sale. The suitable temperature for transportation and storage was 1-5 ℃.