The vegetable farmers should be vigilant against cold air after the beginning of the spring and do a good job in preventing cold. Cold spring cold and late spring frost are two types: Low temperature cold damage mainly occurs in early spring, causing damage to spring vegetables such as rot, dead seedlings, falling and fruit falling, and early convulsions; late spring frost usually occurs in mid-late April, causing the field to grow. Frost on the surface of vegetable plants causes damage. Here are some precautionary measures against cold spells: First, low-temperature refining seedlings After the seedlings emerge, the seedbed should be ventilated, and gradually increase ventilation with warmer weather. The seedlings should be subjected to low-temperature exercise to improve the cold resistance of the seedlings and to adapt to outdoor low-temperature environment. Second, increase protection facilities There are two ways to increase protection facilities: First, build wind barriers. The wind barrier has a blocking effect on the cold air and prevents the surface from further cooling. The second is planting trenches and covering the mulch. When planting vegetables in early spring, the ditching planting method can be adopted, and the ditch depth requires more than the height of the seedlings, and then the dura can be covered with a plastic film. Third, temporary warming In the production of protected land, when the cold current comes, temporary heating can be carried out in the nursery shed or production shed by means of building a simple coal stove or installing electric lights to increase the temperature inside the shed and prevent freezing damage. IV. Water well water When strong cold air passes, the weather is clear, there is no wind or breeze during the night, and the temperature drops rapidly, especially when the local surface temperature falls below 0°C. When the frost occurs, well water can be poured on the ground to increase the ground temperature. This method can increase the ground temperature from 0 °C to 8 °C, to avoid frost. V. Smoke On a frosty night, smoking in the fields can effectively reduce or avoid frost disasters. But pay attention to two points: First, the fireworks should be more dense, so that the smoke screen basically covers the whole park; Second, the lighting time should be appropriate, should be in the wind direction, from midnight to 2 o'clock in the morning, until the sunrise, there is smoke enveloped On the ground, this works best. Six, the amount of water spray Before the occurrence of frost, spraying the water on the surface of the plant with a sprayer can slow down the body temperature and increase the content of water vapor in the atmosphere. The water vapor condenses and releases heat to mitigate frost damage. Seven, timely cultivator Cultivating before frost can reduce the degree of frost damage. Because the spring temperature gradually rises, after the clay is loosened, more solar energy can be absorbed and stored. Once the frost comes, the frost can be alleviated because some of the heat has accumulated in the soil. Nucleic Acid Extraction Reagent Kit 64T(auto) extraction kits,DNA purification Kit,reagents rna extraction,rt-pcr ki Shenzhen Uni-medica Technology Co.,Ltd , https://www.uni-medica.com