In winter and spring season, vegetables cultivated in plastic greenhouses are prone to frost damage. Several effective antifreeze methods are introduced.
1. Multi-layer coverage According to observations, a small arch shed in a plastic greenhouse can increase the temperature in the small arch shed by 2 to 4°C and increase the ground temperature by 1 to 2°C. In the greenhouse, a plastic film is used to form a double-layer curtain at night. Covering can increase the average temperature and ground temperature within the shed by 1~2°C. It covers a layer of grasshoppers 1m high around the greenhouse and can increase the temperature of the shed by 1~2°C.
2. Covering the film with the plastic film can generally increase the ground temperature at 10 cm by 2~3°C, and the ground minimum temperature by about 1°C. At the same time, because the film is not gas-permeable, it can suppress evaporation of water, reduce the number of watering, and indirectly increase the temperature.
3. The ridge cultivation has a large ridge surface area, receives more light during the day, and absorbs more heat from the air, thus warming up quickly. However, ridges should not be too high or too wide. Generally, they should be 15 to 20 centimeters high and 30 centimeters wide.
4. Keep the shed film clean and increase the amount of heat entering the shed. The heat mainly comes from solar radiation. When sunlight enters the shed through the shed film, part of the light energy is converted into heat energy due to the “greenhouse effectâ€. Water droplets and dust on the film have a great influence on the lighting conditions in the shed. According to observations, a layer of water droplets adheres to the shed film, which can reduce the light transmittance by 20 to 30%. After the new film is used for 2 days, 10 days and 15 days, the light in the shed can be reduced by 14% and 25% due to the contamination of dust. , 28%. It can be seen that keeping the shed film clean is beneficial to increase the amount of light and increase the temperature of the shed.
5. The discharge of biogas in the plastic greenhouse can release the biogas, which can increase the temperature and replenish the gas (that is, supplement carbon dioxide gas), thereby promoting the growth and development of vegetables; According to experiments in greenhouses such as cucumbers, tomatoes, green peppers, cauliflower and other vegetables, generally can increase production 20 ~ 40%.
6. Increasing the temperature of fire by using firewood or crop straw can also increase the temperature of the greenhouse. However, it is necessary to observe changes in the temperature of the greenhouse at any time, so that timely and appropriate, to prevent excessive smoking smoked seedlings.
7.Scientifically watering vegetables in winter to water, in order to achieve "five-watering and no pouring," that is, pouring water without pouring yin (watering on sunny days, no watering on cloudy days), and not watering before pouring (watering before noon, (No watering in the afternoon), pouring a small water (not pouring water, not flooding irrigation), pouring temperature not pouring cold (winter water temperature is low, when watering, first in the shed to warm up, until the water temperature is close to the ground temperature Pouring), pouring dark not pouring (casting dark water, not pouring water).
8. Use the storage tank to store a storage tank every few minutes in the center of the heat storage greenhouse. The bottom of the tank is covered with a plastic film, then filled with clean water, and then a transparent film is placed on the upper part of the pool to prevent evaporation of water in the pool and increase the shed. The air humidity inside. Since the specific heat of water is relatively large, the heat absorbed at high temperatures at noon can be released at night.
9. Promote the use of aluminum film reflective screen Polyester aluminized film spliced ​​into 2 meters wide, 3 meters long reflective screen, hanging in the upper post of the plastic greenhouse, hanging down to the ground. In this way, the ground can be increased by 40 to 43%, the greenhouse temperature can be increased by 3 to 4°C, the ground temperature can be increased by 1.8 to 2.9°C, the cucumber can be increased by 20 to 25%, and the tomato can produce 41.8 to 58.1%, and the quality can be improved. In addition, the laying of silver gray film or aluminum foil on the ground can also increase the light intensity between the plants, so that the vegetables and vegetables can be well colored and prevent the premature decay of the lower leaves.
10. The use of straw reactor technology to standardize the operation using this method, the coldest time in winter can increase the temperature of 20 cm 4 ~ 6 °C, greenhouse temperature increased by 2 ~ 3 °C.
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