Cultivation techniques of lettuce

1. Climatic conditions

Lettuce likes the cool climate, and the lowest temperature for seed germination is 4 ℃ for a long time. The optimum temperature for germination was 15: 20 ℃, germinated at 3: 4 days, and was blocked at more than 30 ℃. Therefore, low temperature treatment should be carried out when sowing in summer to promote the activity of enzymes and the transformation of other substances in the seeds. The optimum temperature for stem and leaf growth of heading lettuce was 11-18 ℃, and the optimum temperature for heading stage was 17-18 ℃. The seedlings can withstand low temperature of-5 ℃. It is not easy to form a leaf ball above 21 ℃ or the internal temperature of the leaf ball is too high, which leads to necrosis and decay of the heart leaves. When the temperature is above 30 ℃, the growth is poor. The temperature adaptation range of non-heading lettuce is wider than that of heading lettuce. For the sensitivity to sunlight, the early-maturing variety was the most sensitive, the middle-maturing variety was the second, and the late-maturing variety was slow.

2. Soil conditions

Lettuce is suitable for slightly acidic soil, which is planted in soil rich in organic matter, with strong water and fertility conservation and high yield. for example, when planted in dry and water-deficient soil, the root system is underdeveloped, the growth is not full, the vegetable taste is slightly bitter and the quality is poor.

3. Water condition

Lettuce in different growth periods, different moisture requirements, seedling stage can not be dry can not be too wet, too dry seedlings easy to aging, too wet seedlings easy to grow in vain. In the budding stage, the moisture should be properly controlled, the moisture in the heading period should be sufficient, the water deficiency leaves are small, and the taste is bitter. Do not have too much water in the late stage of heading, so as not to crack the ball and lead to disease.