How to avoid seedling injury of protected vegetables in low temperature season

(1) Strictly guard against wind, rain and snow disasters.

The meteorological disasters caused by the super cold wave will vary from place to place, and all localities should strengthen their prevention. First, prop should be appropriately added in the shed with weak skeleton to strengthen the shed skeleton and improve the shed's ability to resist snow and ice disasters. The second is to close the shed, compress the shed film, and fix the external thermal insulation cover to prevent the wind disaster. Third, clear the snow on the shed in time to prevent the shed from collapsing due to heavy snow and blizzard. Fourth, we should dredge the drainage ditch in the shed area to ensure the smooth drainage system and prevent rainwater from flowing backwards into the shed.

(2) Strengthen heat storage and insulation measures.

1. Proper heating and heat storage during the day. The characteristic of this cold wave is that although the cooling intensity is large, it comes and goes quickly, and it will not be accompanied by continuous rain, snow, fog and low temperature. However, it is now in the cold season, and the temperature will slowly rise after strong cooling. All localities should take advantage of the short process of this super cold wave and the rainy and snowy weather. After the weather clears up, the temperature management index of greenhouses during the day should be appropriately improved to increase heat storage and cope with the continuous low temperature. Cucumber, towel gourd, bitter gourd, cowpea, watermelon, melon and other heat-resistant vegetables should be kept at 30 ~ 35℃ in the greenhouse as far as possible; Tomatoes, zucchini and other vegetables that like temperature and are not heat-resistant, try to keep the temperature in the shed at 24 ~ 28℃ during the day; For other vegetables that like temperature, try to keep the temperature in the greenhouse at 28 ~ 32℃ during the day; Vegetables that like cold should also be raised at room temperature during the day. In the afternoon, the temperature index of the outer insulation cover is 2 ~ 3℃ higher than that before the cold wave strikes. The above are emergency heating and heat storage management measures. When the weather warms up to the cold wave, the greenhouse temperature will return to the conventional management index.

4. Increase the coverage of external insulation. Before the cold wave strikes, a layer of plastic film should be covered on the external thermal insulation covering such as grass, moisture absorption and thermal insulation quilt to prevent the external thermal insulation covering from reducing the thermal insulation effect after absorbing water, so as to help clear the snow on the shed.

3. Strengthen internal thermal insulation measures. Heat preservation curtain is added in the shed, which is opened during the day and hung at night. A thick thermal curtain is hung on the communication door between the buffer room and the greenhouse. The shed room is added with a simple middle shed and a small arch shed to form three sheds and four pieces at night; If there are idle sun-shading nets or non-woven fabrics, you can also cover the sun-shading nets and non-woven fabrics on the inner thermal insulation small arch shed at night.

(3) Take emergency temperature compensation measures.

When the greenhouse temperature of warm-loving vegetables is continuously lower than 5℃ and cold-loving vegetables are continuously lower than 0℃, temporary temperature compensation measures such as electric fans and hot stoves should be taken, or geothermal lines should be laid in the cultivated border soil in advance, and if necessary, electricity should be applied to raise the ground temperature and air temperature.

(4) Enhance the stress resistance of plants.

1. Spray foliar nutrition. In order to enhance the stress resistance of plants, 0.3% potassium dihydrogen phosphate +0.3% calcium nitrate+1% glucose solution should be sprayed in sunny afternoons after the cold wave, together with insect-repellent chemicals.

2. Strictly control irrigation. It is forbidden to water in the low temperature period before and after the cold wave, so as not to reduce the ground temperature and aggravate the freezing injury. After the weather gets warmer, normal water management will be resumed. Watering vegetables in winter and spring facilities should be "three watering and three not watering", that is, watering on sunny days, not watering on cloudy days, watering before noon, not watering in the afternoon, until the end of watering.