Key points of lettuce cultivation in solar greenhouse in winter

Lettuce (var. Ramosa Hort.) Leaf lettuce, also known as goose lettuce, shipping mark lettuce, lettuce, belongs to the genus Asteraceae lettuce. For annual or biennial herbaceous crops, leaves long Obovate, dense into cabbage-like leaf balls, edible, crisp, tender and refreshing, slightly sweet.

Morphological characteristics of lettuce according to the color of leaves, lettuce can be divided into green lettuce and purple lettuce. For example, according to the growth state of leaves, there are two kinds of lettuce: loose leaf lettuce and heading lettuce. The former leaf lettuce made (20 pieces) scattered, the latter leaf clasped into a ball. If subdivided, there are three types of heading lettuce, one is creamy lettuce with Obovate leaves, smooth leaves, soft texture and slightly corrugated leaf edges, and the other is crisp lettuce with Obovate round leaves, wrinkled leaves, crisp and tender texture and serrated leaf edges.

The latter cultivation is more common; bitter leaf lettuce leaves thick, long oval, leaves entire, semi-globular. The weight of single plant of loose leaf lettuce is 250ml 500g. The growth period of heading lettuce is longer than that of loose leaf lettuce, and the weight of single plant is higher than that of loose leaf lettuce, which is generally 400ml 750g. The late ripening varieties with long growth period can reach more than 1000 grams. The root system of lettuce is shallow, the whisker root is well developed, the main root group is distributed in the 20 cm soil layer on the surface, the stem is short, the leaves are alternate, there are lanceolate, oval, oval, etc., the leaves are green, yellow-green or purple, the leaf surface is spreading or wrinkled, the leaf margin is wavy or shallowly lobed, the outer leaves are unfolded, the heart leaves are loose or clasped into leaf balls, the seeds are gray-white or black-brown, and the weight of a thousand seeds is about 1 gram.

The medicinal value of lettuce: the nature of lettuce is sweet and cool, because it contains lettuce in its stems and leaves, so it tastes slightly bitter, and it has the effects of clearing heat and refreshing, analgesia and hypnosis, lowering cholesterol, auxiliary treatment of neurasthenia and so on. Lettuce contains mannitol and other active ingredients, which is beneficial to urine and promote blood circulation, clearing liver and gallbladder and nourishing stomach.

The edible value of lettuce: lettuce is rich in nutrition, containing a lot of β-carotene, antioxidants, vitamin B1, B6, vitamin E, vitamin C, as well as a lot of dietary cellulose and trace elements such as magnesium, phosphorus, calcium and a small amount of iron, copper and zinc. Strengthen the digestion and absorption of protein and fat, improve the blood circulation of intestines and stomach, you can often eat lettuce.

Key points of lettuce cultivation in solar greenhouse in winter

Variety selection

Middle and late ripening heading lettuce varieties with strong cold resistance should be selected for cultivation.

Cultivation date

Cultivation in solar greenhouse can be planted from mid-late November to late January of the following year, and harvested from the first and middle of January to early March.

Raising seedlings

Choose fertile sandy loam, fine and make a flat bed. Then apply 100 kg of sifted high-quality manure and 0.5 kg of potassium dihydrogen phosphate every 10 square meters, mix well, level the border surface, water, and sow seeds. Generally use dry seed sowing, can also soak seeds to accelerate budding after sowing. Dry seeds should be sowed with 75% chlorothalonil wettable powder equivalent to 0.3% of the seed weight, but should not be placed for too long. The seeds should be soaked in 20 ℃ warm water for 6-7 hours, then wrapped in a cloth bag after being removed, placed under 20 ℃ to promote budding, rinsed with clean water once a day, and budded after 2-3 days. Choose to sow seeds on a windless and sunny morning, sowing 3-5 grams of seeds per square meter of seedling bed. After sowing, it is covered with a layer of fine soil 3-5 mm thick.

Soil preparation and fertilization

Before planting, 5000 kg of rotten organic fertilizer and 30kg of compound fertilizer were applied per mu. After turning deeply, flat beds can be made, and those covered with plastic film can be made into small high beds.

Colonization

Solar greenhouse cultivation generally row spacing of 40 cm, plant spacing of 30 cm, watering and cutting tuo before seedling, bring more soil. Open ditches or dig holes for planting, close ditches and flat beds and pour enough water for planting.

Post-planting management

After planting, the daytime temperature was kept at 20 ℃ ~ 24 ℃, and the night temperature was above 10 ℃. During the slow seedling period, the soil was ploughed and loosened for 1 and 2 times. After slowing down the seedling, the appropriate temperature should be 15 ℃ ~ 20 ℃ during the day, and the slow seedling water should be irrigated 7-10 days after slow seedling, at the same time, chemical fertilizer should be applied lightly, about 10 kg per mu. After that, ploughing again and squatting seedlings properly. About 15 days later, when the rosette leaves had grown and the heart leaves began to cover the heart, compound fertilizer or ammonium nitrate was applied 15-20 kg, and topdressing was applied again in the heading period. Watering times in winter should not be too much, in case the ground temperature or humidity is too high. When entering the pilling stage, the water supply should be uniform, do not suddenly dry and wet, so as not to crack the ball or make the ball leaf open and grow. Stop watering 3-5 days before harvest.