1 Variety selection: Choose varieties with strong cold resistance, disease resistance and strong adaptability, such as the emperor, Salinas, and Great Lakes 659. The nursery should choose fertile sandy loam with strong water retention and fertility.
2 Seedling preparation: As the seeds of lettuce are small, the seedbed cultivation requires strict, the site preparation should be fine, and the bed and soil should be fine and flat. 10 kg of farmhouse manure, 10 kg of diammonium phosphate, and 0.3 kg of potassium dihydrogen phosphate were thoroughly crushed and used per 10 m2 of seedbed. Spread the ground evenly, plowing 10-12 cm, plowing and plowing and leveling and practising.
3 Seed treatment: lettuce seeds can be sowed, but also soaked germination. When seeds are sown, they should be seeded with 75% chlorothalonil wettable powder equivalent to 0.3% of the dry weight of the seeds before sowing. Immediately after sowing, seeds should be sown overnight.
When soaking germination, first soak seeds in water at about 20°C for 3 to 4 hours. After washing, drain the water, put it in a wet gauze bag or pot, and germinate at 20°C. Rinse with water once a day. After germination, germination will continue. Buds can be budded in 2 to 3 days. When the temperature is too high under natural conditions, the germination can be placed on the wellbore or at a cave or the like, and the temperature is controlled at 15 to 20°C.
4 Seeding: Before seeding the seedbeds, pour in enough water. When the drowning water does not seep through, sifted soil shall be leveled. After the water seeps, sieve 0.1-0.2 cm thick fine soil and sow. Use 375-450 grams per hectare. In order to nurture strong seedlings and prevent seedlings from becoming leggy and forming tall or weak seedlings, sowing should not be too dense. It is generally advisable to broadcast 1 gram per square meter of seedbed. For uniform seeding, the seeds can be mixed and spread in 2 separate shots, and the sieved soil is then covered with 0.3-0.5 cm. To prevent the loss of water, straw, wheat straw, or mulch can be applied to the surface according to the ground temperature. In order to prevent ants, cockroaches, etc. from eating seeds, sow dimethoate and dichlorvos on the bed after sowing.
5 Seedling management: generally keep the bed temperature after sowing 20 ~ 25 °C, wet surface, 3 ~ 5 days can Qimiao. If the temperature is too high, it should be shaded properly to create a cold and moist environment for the seedlings to grow robustly. When the seedlings have just been excavated, the coverings on the surface shall be promptly removed to prevent the formation of tall plantlets with excessively elongated embryonic axes.
After the emergence of 18 ~ 20 °C, 8 ~ 10 °C at night. After emergence, 7 to 10 days, when the young seedlings have a two-leaf heart, they should be divided in time and the seedlings should be 3 to 5 cm apart. After seedling, it should be sprayed with 500 times potassium dihydrogen phosphate solution or watered with water. At the seedling stage, it is necessary to spray 1 to 2 times of 75% chlorothalonil WP or 70% thiophanate-methyl wettable powder 600 to 800 times to control seedling diseases. The seedling age is 25 to 35 days, and it can be planted when there are 4 to 5 true leaves.
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Plastic centrifuge tubes are commonly used in the laboratory. Since glass centrifuge tubes cannot be used in high-speed or ultra-high-speed centrifugates, plastic centrifuge tubes are generally used more.
Scientists often use centrifuge tubes to separate solids, liquids, and gases. You can separate solid particles from liquids, like plasma and blood cells. You can do this by spinning the Centrifuge tube that carries the material at high speed. The centrifuge tube allows centrifugal force to push heavier material to the bottom of the tube. The centrifuge tube facilitates the preservation of samples to be separated by centrifugation. Typically, these centrifuge tubes can handle a small number of samples. Researchers used different types of centrifuge tubes for different tasks and procedures.
Centrifuge tubes are essential for sample separation, delamination, or density gradient separation using centrifuges. Centrifuge tubes have a variety of applications in biology, particularly cell culture and microbiology, chemistry, clinical healthcare, and wider industrial Settings.
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