Planting techniques of lettuce in open field

Variety selection: cold-tolerant varieties should be selected in early spring, while heat-resistant and bolting-resistant varieties should be selected in summer and autumn. Planting method: first raise seedlings and then plant, per mu can apply appropriate amount of mature manure, ternary compound fertilizer, potassium sulfate. Water management: keep the soil moist and fertilize with water every time. Control downy mildew: control field humidity and spray enylmorpholine. Prevent stem cracking: spray borax solution.

I. Variety selection

There are many varieties of lettuce, and the excellent varieties are Hangzhou tip lettuce and Jinan white lettuce. Generally speaking, cold-tolerant varieties should be selected in early spring, while heat-resistant and bolting-resistant varieties should be selected in summer and autumn.

II. Planting methods

The main results are as follows: 1. Generally, lettuce is planted first and then planted. The seedling age is about 40-50 days. When the seedlings grow to 4-6 true leaves, soil preparation is needed before planting. 2000kg, ternary compound fertilizer 50kg and potassium sulfate 30kg can be applied per mu of rotten manure.

2. Applying more potassium fertilizer during the period can effectively improve the taste of lettuce and make it more sweet, crisp and tender, then turn the ground and rake flat to make a flat bed, the row spacing of lettuce is 30cm × 30cm, water should be watered thoroughly after planting, and squat seedlings should be properly carried out.

III. Water management

1. When lettuce grows to about 8 true leaves, it will begin to grow. At this time, it is necessary to end squatting seedlings, and the amount of water should not be too large, generally watering every 7 days or so.

2. When the stem begins to expand, the demand for water and fertilizer will gradually increase, during the period to keep the soil moist, each watering should follow the water to fertilize, generally per mu of land can apply compound fertilizer 5kg or so.

IV. Scientific topdressing

The main results are as follows: 1. After planting slow seedlings of lettuce, it is necessary to apply fertilizer to extract seedlings in time, apply 2 square of rotten manure water and urea 10kg per mu of land, and do not apply chlorine-containing fertilizer to lettuce, otherwise it will affect the taste.

2. Bolting fertilizer can be applied when the fleshy stem of lettuce begins to expand, urea 10kg and potassium sulfate 15kg are applied with water per mu, while the mid-late maturity varieties can be fertilized again after 15-20 days.

Prevention and control of downy mildew

1. Downy mildew is a common disease in growing lettuce, which is generally caused by excessive watering during the expansion of the succulent stem of lettuce, hypertrophy of leaves and poor ventilation between rows.

2. During the period, the humidity in the field should be controlled and 1000 times of duofu or 1000-1500 times of enamylmorpholine should be sprayed for control.

VI. Prevention of stem cracking

If the lettuce is seriously boron deficient, it is easy to cause the fleshy stem to crack. Generally, 0.2% borax solution can be sprayed on the leaf surface for 2-3 times after the fleshy stem is enlarged, and when the terminal core leaf at the top of the lettuce is flat with the rest of the leaves, it can be harvested, otherwise the lettuce will easily grow old, resulting in more fiber.