Every winter and spring, due to factors such as cold currents, inadequate insulation of greenhouses, excessive ventilation, and so on, greenhouse vegetables suffer from cold or cold injury. Therefore, farmers are reminded to take precautions.
The performance of vegetables after freezing
Leaf victim. It belongs to mild freezing injury. In the cotyledon stage, the damage of the cotyledon appears as chlorosis on the edge of the cotyledon, with “white borderingâ€, and the true leaf growth is not affected after the temperature returns to normal. After the colonization, a short-term low-temperature or cold-air invasion occurs, and the leaf edges of the plants are frozen. Dark green, gradually dry.
Root victimization. The root growth was stopped and no new roots occurred. Some old roots were yellow and gradually died. A sudden increase in temperature causes plants to wilt or slow down. Plants with severe damage are difficult to recover.
Growing point victim. Belong to the more serious freezing injury, often cause the top buds to be frozen, do not send new leaves, if the weather can not be restored after the warm weather.
Fruit and fruit damage. The cold weather during the flowering period of vegetables will affect the pollination and fertilization effects, resulting in a large number of flowering, falling, or malformed fruits.
Precaution
1. Seedlings should be prepared at low temperature. During the growth of the seedlings, strict control of temperature is required to prevent the seedlings from being overly thin, and the seedlings will not be allowed to grow in size, and a large temperature difference will be taken to increase the resistance of the seedlings. The seedling bed needs to be ventilated for seedlings and planting two days before the seedlings are planted to carry out the seedlings. Cold exercise.
2. Strictly grasp the time of colonization. In order to promote the timely planting of the planted vegetables, the cold-cold-head warm-weather weather should be selected in the winter and spring seasons in order to facilitate rapid seedling growth after planting and improve resistance.
3. Strengthen the coverage of insulation. After low-temperature planting, a small shed can be buckled in the shed, a bamboo frame can be used as an arch, and the film can be covered at night. If necessary, the grass can be covered on the film; in the shed, the film can be warmed and moisturized; Using a plastic film as an apron, can significantly reduce the cold air at the bottom of the invasion; can also be set in the greenhouse canopy, and enhance the insulation effect; cold seasons, attention to block the gaps throughout, to minimize heat dissipation gap.
4. Artificial temporary warming. When the daytime temperature in the greenhouse is lower than 15°C and the nighttime temperature is lower than 8°C, cold or freezing damage may occur. At night, temporary warming measures must be taken. The specific method is to ignite dry stalks or sawdust in the shed. Such as smoke, or burning honeycomb coal stove, can temporarily increase greenhouse temperature, but it should pay attention to timely ventilation to eliminate harmful gases. It can also be heated by lighting in the shed. Conditional use can be made of temporary heating equipment to artificially supplement heat energy.
5. Management after cold hazards. After suffering various degrees of cold damage or frost damage, vegetables should actively take remedial measures. The first is to avoid light. Frozen vegetables cannot receive light immediately, and they should be covered with straws or quilts on the shed film, or covered with frozen foods such as newspapers, so that the frozen vegetables will thaw slowly and resume growth; Slowly warming. In the greenhouse, no rapid warming measures can be used to thaw. In addition to shading, measures such as appropriate air release can be used to increase the temperature of the greenhouse slowly. Third, supplement water. After the vegetables are frozen, they can be properly watered, or they can spray water on the vegetables and the ground immediately after freezing, to prevent the ground temperature from continuing to drop and the dehydrated and dried vegetables from drying out. Fourth, spraying and preventing diseases. After the vegetables have grown up, cut off the frozen parts, spray them with 50% Suo Ke Ling WP 2000 times, or fumigate with 10% SuoQing smoker to prevent gray mold; Fifth, strengthen management. After the frozen vegetables are thawed, they should be prevented from re-freezing, loosen the soil in time, apply the quick-applied fertilizer in an appropriate amount, and promote growth.