This year, Heilongjiang Province continued to experience low temperatures and heavy rain in spring. In some areas, snowfall over a long period of May holiday also caused vegetables to suffer cold damage or frost damage at different temperatures. The lighter ones caused the reduction of production and income, and the severer plants were frozen to death. What are the symptoms of low-temperature chilling injury and how do farmers' friends respond? First, the main performance of low-temperature hazards is the damage to the above-ground leaves (mainly the leaves and the growing point). Victims of the leaves are often mildly affected. If they are victimized at the cotyledon stage, the edges of the cotyledons become chlorotic, with white borders, and normal temperature does not affect the production of true leaves. After planting, the plant suffered a short-term low-temperature or cold-wind invasion, and the leaves of some plant parts were frozen and dark green and gradually dried off. The damage at the growing point is a more serious freeze injury. It often causes the top buds to be frozen without new leaves. If this condition cannot be restored after the weather has warmed up, it must be supplemented separately. The second is root damage. The temperature in the shed is low, and the ground temperature also falls below the minimum temperature for root growth. Root growth stops, new roots do not accumulate, some of the old roots turn yellow, and they gradually die, causing sapling roots. When the temperature suddenly rises, the plants show wilting or growth rates. Slow down. If it is seriously affected and it is difficult to resume growth, it is necessary to change the seedlings again. Second, the greenhouse protection to prevent cold damage measures First, seedlings to do a good job at low temperature hardening. In the seedling stage, low temperature exercise can start from the seed germination. When the seeds are germinated, the temperature is slightly lower, and then gradually (8 to 26° C.) is increased to the appropriate germination temperature of various vegetable seeds. After the seedlings germinate, the temperature is then lowered. Stout and get exercise. During the growth of seedlings, the temperature is strictly controlled, the seedlings are not allowed to grow too thin due to excessive temperature, and the measures for raising seedlings are adopted to increase the resistance of the seedlings. The seedbeds need to be ventilated for seedlings and planting two days before the seedlings are planted. Cold exercise. The second is to strictly grasp the time of planting. In order to promote the timely easing of seedlings after planting, the cold tail warmer should be selected to weather the planting in order to facilitate rapid seedling growth after planting and improve resistance. The third is to strengthen the coverage of insulation. Covering the film at night, conditions can also cover grasshoppers on the film; the bottom of the shed with a plastic film for the apron, can significantly reduce the cold air at the bottom of the invasion; also pay attention to block the gaps throughout, to minimize heat dissipation gap. Fourth, artificial temporary warming. In the vegetable greenhouse, the daytime temperature is lower than 15°C, and when the nighttime temperature is lower than 8°C, cold or freezing injury may occur. At night time, temporary heating measures must be taken. The concrete method is: stay away from the vegetable in the shed, burn the honeycomb coal stove or Heating with lighting in the shed can temporarily increase the temperature of the greenhouse. Conditional use of temporary heating equipment can be used to artificially supplement heat energy. Third, the low-temperature hazards of pharmaceutical treatment measures with high-efficiency plant growth regulator Tianfengsu 10 ml water 30 to 40 kg evenly sprayed on the crop leaf, but also after 3 to 5 days and then spray once. They can promote the development and regeneration of plant roots, restore plant growth, and have a definite healing effect on cold hazards. At the same time, in order to promote the easing of seedlings, we must also pay attention to raising the ground temperature, and we should appropriately control the amount of watering, timely soil loosening, and increase the lighting time as much as possible every day, but we must pay attention to the seedlings gradually see light, so as to avoid the phenomenon of “flash seedlingsâ€.
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