Recently, cold currents have invaded most of northern China. Heilongjiang, Jilin, and Liaoning provinces dropped the first snowstorm this year. Temperatures have also dropped sharply, and greenhouse crops are prone to freeze damage. Pepper and cucumber were reduced to 12°C at room temperature, tomatoes dropped to 10°C, and watermelons and eggplants fell to 5°C, prone to frost damage. After the occurrence of frost damage, if it is not scientifically remedied, it will cause serious losses: light, stagnant growth, yellowing of the plant, even if the growth is restored, the plant is dwarf, the leaf is small, the section is short, the fruit is small and deformed, and the yield and quality are reduced; Under heavy freezing, the plants appeared wilting and wilting, and the plants died or even died. After the crop is frozen, remedial measures can be taken according to local conditions:
After the shading and sunscreen are flowing in cold weather, it is generally sunny weather and the sun is relatively strong. If you let the sun shine on frozen plants, you can easily cause dehydration and wilting of frozen tissue, and even death. Therefore, after the sun comes out, it is necessary to cover the surface of the greenhouse membrane with a layer of light leakage grasshoppers, or to set up shade in the interior to reduce the intensity of sunlight. Before evening, be sure to cover the shed tightly to prevent freezing damage from happening again. In the strong light period around noon the next day, shades need to be properly covered and can be transferred to normal management later.
Appropriate top-dressing fertilizers can be applied by top-dressing crops and frozen crops, which can not only improve the nutritional status of crops, but also increase the concentration of cell tissue fluids, enhance their cold-resistance and antifreeze capacity, and promote the restoration of growth. Using foliar fertilizer than soil topdressing can save both fertilizer and quick results. According to the characteristics of different crops need fertilizer, reasonable fertilizer. For melons and solanaceous vegetables, the demand for nitrogen, phosphorus, and potassium in life is relatively balanced. It is advisable to use ternary compound fertilizer or potassium dihydrogen phosphate; leafy vegetables have the most demand for nitrogen and can be sprayed. Application of 1%~2% urea aqueous solution, and then the addition of an appropriate amount of gibberellin better; root vegetables, the demand for potassium, phosphorus and other elements more, can be sprayed with 0.3% potassium dihydrogen phosphate or 1% potassium sulfate solution . Spraying should be meticulous and thoughtful, so that the positive and negative sides of the blade are stained with fertilizer solution. Water can also be used in combination with fertilizing the road. Due to the decreased resistance of frozen plants and the susceptibility to diseases, the addition of suitable fungicides to the fertilizer solution is beneficial to the recovery of frozen tissues and to the prevention of disease occurrence.
Watering in time after the occurrence of freezing water damage. Watering can increase the heat capacity of the soil, inhibit the ground temperature from continuing to drop, stabilize the surface air temperature in the surface and the shed, and effectively reduce and control the development of freezing damage. Because the temperature of the well water is higher than the ground water, well water is used for irrigation. The amount of water to infiltrate the plow layer is appropriate, should not flood irrigation, so as to avoid causing damage.
In scientifically ventilated cold-shedding areas, neither the horse can warm up nor can it be ventilated prematurely. If the ventilation is too early, the freezing injury will be aggravated. If the temperature rises too fast, the crop will be dehydrated by the frozen cell tissue and the plant will die. Therefore, after the sun comes out, it is necessary to gradually open up the vents as the temperature of the greenhouses rises, so that the greenhouses will gradually warm up, so that the frozen crops will have an adaptation process. After a period of time, the vents will gradually shrink after 2 pm. Closed completely before 4 o'clock. This will ensure that the frozen tissue will fully absorb enough water to promote cell revival and restore growth.
To cut off the frozen leaves of dead branches and severe damage to cold, the branches and leaves that cannot be restored should be cut off as soon as possible and removed outside the shed. This will not only reduce the water consumption and nutrients of frozen leaves and leaves, promote the recovery of frozen plants, but also prevent mildew and induce disease. After the fruit trees in the greenhouse are cut off from frozen shoots, the effect on restoring growth is significant.
When the aircraft is immediately turned and turned over to the severely-frozen greenhouse, if the above-mentioned remedial measures cannot fundamentally solve the problem, it is necessary to take the opportunity to immediately turn the crops adapted to the season in order to avoid delays in agricultural production and greater losses.
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