Recently, the temperature has gradually decreased, and cold waves may strike at any time. In such weather, the vegetables in the greenhouse often suffer from frost damage. In order to minimize losses, farmers' friends must do a good job in the management of greenhouse vegetables from the following three aspects:
First, strengthen the greenhouse before the cold wave approaches
Rainy and snowy days, cloudy days and cold waves are the three major meteorological disasters in winter greenhouse vegetables. They can damage plastic greenhouses, so vegetable farmers should take precautionary measures early.
1. Always check the tightness of the film line. The south end of the film line is fixed on the ground anchor, and a sandbag tied at the north end is poked outside the north wall. The elasticity of the film line can be adjusted at any time, which has a good windproof effect.
2. Repair the greenhouse film. Use transparent tape to repair the damaged part of the shed film at any time to prevent strong wind from blowing in and damage the shed film.
3. Prepare relevant materials. Prepare a certain number of sand bags with a thickness of 10 cm and a length of about 1 meter, and place them on the back slope. When the wind blows the shed film up and down, it will be pressed on the shed film in time, which has a good windproof effect.
2. Strengthen timely management of greenhouses during the cold wave
1. Light transmission. When there is no light during the rainy and snowy daytime, part of the grasshopper must be opened to allow the scattered light to penetrate, and the vegetable seedlings can still perform weak photosynthesis to maintain the slow growth and development needs. Don't leave the rice dumplings uncovered all day long, so that the vegetable seedlings can spend the day in the dark, which is very unfavorable for vegetable seedling growth and easily causes various diseases. Failure to expose the rice dumplings for more than two days will result in the wilting and death of vegetable seedlings.
2. Cover the pupae in time to clean up. When the rainfall and snow temperature is not too low, if it starts to snow or rain during the day, immediately lift the pupa and clean the snow on the shed film after stopping the snow; if it is snowing at night, after the snow is cleared in the morning It is also necessary to immediately lift the pupae; if it is snowing and raining for several consecutive days, cleaning it continuously, and only revealing half or half of the flower calyx, remember not to expose it. There are continuous cloudy days for more than two consecutive days. After sunny days, you must not open all the grasshoppers at once to prevent the thin seedlings that have passed through the catastrophic weather from seeing bright light. In addition, the temperature in the shed has increased sharply, and the seedlings have increased water evaporation. The soil temperature is low, and the root system absorbs water very slowly, which causes the body to lose moisture and temporarily wither. At this time, part of the grasshopper should be lowered as soon as possible to block the temperature and cool down. After the vegetable seedlings resume to grow, they should be opened again. After repeated two or three times, the vegetable seedlings can grow normally. Otherwise, temporary wilting can be turned into permanent wilting and death, which is also one of the important reasons for the failure of some greenhouse vegetables. In this period, people cannot be separated from the shed every day, and the flowers or half of the flowers should be exposed at any time, that is, the cover and the cover should be exposed until the plants or seedlings return to normal.
3. Ensure the low temperature limit in the shed. As long as the temperature in the rainy and snowy shed is above the minimum limit, it is not necessary to increase the temperature. For the vegetable varieties of solanaceous fruits, melons or beans, the minimum limit for the temperature of the shed in the nursery and growing period is not less than 5 ℃ The lowest temperature is not less than 10 ℃; the light intensity of the greenhouse is not less than 50Klux, so in the management of severe weather, the warm light should be done according to the above minimum standards, so that the vegetable seedlings can survive the severe weather at low temperature, reducing Nutritional consumption in the body is conducive to the recovery and growth after sunny days. Otherwise, bad results will occur.
3. Measures to be taken after the cold wave affects the vegetable
1. Cut off the frozen stems and leaves to increase the greenhouse temperature.
â‘ Cut off the injured stems and leaves, so as not to cause mildew and disease.
② Increase the greenhouse temperature. The first is to temporarily create a stove or brazier in a greenhouse, but there must be a chimney to prevent CO poisoning of the plant body, and the leaves of the frozen plant body are thin yellow or wilting. Can increase the shed temperature by 3 ℃ -5 ℃. The second is a greenhouse with a power source: laying ground heating lines on both sides of each trench to increase the ground temperature and the temperature of the shed; using a hot blast stove to blow hot air to increase the indoor temperature; Fluorescent tube; discharge hot gas, etc. Can increase the temperature of the shed 5 ℃ -7 ℃. The third is to add a layer of pupa to the front window outside the greenhouse; use No. 8 iron wire as a support frame in the greenhouse, and then cover a layer of shed film; A small supply shed, which forms a double-layer cover, and can also be covered with a thermal insulation curtain on the pupa. This measure can increase the room temperature by 3 ℃ -5 ℃. However, during the heating process, care should be taken to slowly increase the temperature of the shed to allow the frozen tissue to fully absorb water and promote cell resuscitation. Do not close the shed immediately to warm up. If the temperature rises too fast, the frozen tissue will dehydrate and die. Set up a shade in the shed to prevent the frozen vegetables from losing water due to direct sunlight.
2. Watering in time to increase soil heat capacity. Watering can increase the soil heat capacity, stabilize the air temperature on the ground and in the shed, restrain the temperature drop, and effectively reduce and control the development of frost damage. The key to water management is to coordinate the relationship between watering and raising the ground temperature and reducing the humidity in the shed. It is necessary to ensure the normal demand for soil moisture and nutrients by the vegetables, and to maintain a suitable soil temperature. Watering requires "three attentions". First, pay attention to watering on sunny days, and ensure that there is at least 2 days of fine weather after watering. And it should be watered in the morning, not at noon or in the afternoon, so the water temperature is close to the ground temperature, and it will not greatly reduce the ground temperature. At the same time, underground well water should be used for watering. The temperature of well water is generally about 14 ° C, which is beneficial to maintaining a high ground temperature in the shed, and the distance of the water flow should not be too long. Second, pay attention to watering methods. When watering, we must consider not only the water demand of the vegetables, but also the humidity of the shed. Therefore, it is advisable to use underground watering under the film for watering, as well as small trenches and small water. Third, pay attention to management after pouring. On the day of watering, in order to restore the ground temperature as soon as possible, the greenhouse is generally closed to quickly increase the indoor temperature. After the ground temperature is raised, the air is released in a timely manner to reduce humidity to a suitable range. Such as cucumbers, closed the shed to warm up after watering, so that the temperature in the shed reached about 33 ℃ before the release of air, and the next day to continue to close the shed to raise the ground temperature.
3. Top-up fertilization. Combined with watering of frozen plants, an appropriate amount of quick-acting fertilizer can be applied retrospectively, which can improve the nutritional status of the crops, enhance the cold and freeze resistance of the plants, and promote the early restoration of the plants. Foliar spraying is faster and faster than soil topdressing, and should be reasonably sprayed according to the characteristics of fertilizer requirements of different crops. When spraying foliar fertilizer, it is better to add appropriate amount of gibberellin.
4. Spray some protective agents and insect control agents in time. After the plants are frozen, the diseases and insects are prone to invade. Spray some protective agents, disease control and insecticides in time, and cut the frozen stems and leaves in time to avoid moldy disease and induce disease. Optional protective pesticides, such as 500% solution of 80% complexed mancozeb, 50% of hydrazine 1000 times, 64% of imported antiviral alum 500 times, 50% of Nongli Ling 500 times .
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