Scientific Defense and Management Techniques for Vegetable Production Under Cold Wave Weather

The sudden onset of cold waves poses a serious threat to vegetable production, especially under conditions of protected agriculture and open-field cultivation. Extreme weather factors such as low temperatures, frost, snow, and strong winds can lead to freezing of plants, disease outbreaks, and facility damage. A scientific response to the impact of cold wave weather on vegetable production requires a systematic strategy in areas such as facility reinforcement, temperature control, water and fertilizer management, pest and disease control, light management, and post-disaster recovery.

1. Reinforcement and Maintenance of Facilities to Improve Cold Resistance

Before the cold wave arrives, a comprehensive inspection and reinforcement of the physical defenses of protected agriculture facilities must be conducted:

• Reinforcement of Greenhouse Structures: For older greenhouses or facilities with large spans, additional support columns should be added, and damaged greenhouse films should be repaired to enhance wind and snow resistance. For greenhouses with deformed frameworks, steel pipes or rope tensioning methods can be used to improve stability.
• Insulation and Wind Protection: A highly efficient insulating cover should be placed on the exterior of the greenhouse’s lighting surface, and multiple layers of cold-resistant curtains should be added inside to optimize heat storage. The greenhouse film should be sealed to reduce heat loss, and wind barriers should be set up at air inlets and low-lying areas to reduce the impact of cold air on crops.
• Heating and Supplemental Lighting: Install heating devices (such as hot air stoves, electric heating tubes, or ground heating cables) to maintain appropriate temperatures. In case of insufficient light, reflective films should be hung on the north wall of the greenhouse to improve light utilization. LED supplemental lights can also be installed if necessary to promote photosynthetic efficiency.
• Soil Temperature Increase: Organic mulches such as rice husk ash, wood ash, and straw should be spread on the bed surface to reduce soil heat loss and improve root environment temperatures. For open-field vegetables, non-woven fabrics, plastic films, or shade nets can be used to cover the plants and mitigate frost damage.

2. Rational Water and Fertilizer Management to Enhance Plant Resistance

Under low-temperature stress, reasonable control of water and fertilizer management helps improve the cold resistance of vegetables:

• Leaf Anti-Freezing Treatment: Before the cold wave, plant growth regulators such as Brassinolide, Seaweed Acid, or a 0.3% solution of potassium dihydrogen phosphate should be sprayed to enhance cell activity and improve frost resistance. Additionally, supplementing magnesium, zinc, boron, and other trace elements can improve photosynthesis and cell wall stability.
• Water Management Strategy: During low temperatures, irrigation should be strictly controlled to avoid root damage caused by reduced soil temperatures. Follow the “three irrigation and three non-irrigation” principle: irrigate on sunny days, not on cloudy days; irrigate before noon, not after; irrigate with small amounts of water frequently, not large amounts at once. For low-lying fields with poor drainage, drainage systems should be cleared in advance to prevent waterlogging and frost damage.
• Optimize Light Utilization: During the cooling period, timely pruning and branch management should be done to reduce shading between plants and ensure adequate light penetration. The greenhouse film surface should be regularly cleaned to improve light transmission. For prolonged cloudy weather, artificial lighting can be used to increase light levels.

3. Timely Snow Removal and Drainage to Reduce Frost Damage Risks

Under extreme weather conditions, snowfall and water accumulation may cause disastrous effects on both protected agriculture and open-field vegetables:

• Snow Removal in Facilities: During snowfall, a “snow removal while it snows” strategy must be adopted to prevent snow accumulation from collapsing the greenhouse. Night-time snowfalls should be monitored in shifts to ensure timely snow removal from the greenhouse roof to avoid pressure deformation of the greenhouse film. If the snow is too heavy and there is a risk of collapse, the film should be punctured to release the load and reduce structural damage.
• Open-field Water Accumulation Diversion: In southern regions, the drainage systems of open-field vegetable fields, such as surrounding ditches, ridge ditches, and furrow ditches, should be cleared in advance to ensure quick drainage of rainwater and snowmelt, preventing waterlogging and frost damage. For fields with poor drainage, ditches can be deepened or even mechanical water pumping systems can be used to reduce water quickly.

4. Pest and Disease Control to Improve Plant Health

Under low-temperature and high-humidity conditions, the risk of pest and disease outbreaks significantly increases, requiring comprehensive control measures:

• Humidity Control: Ventilation should be timed, and moisture-absorbing materials (such as dry hay or rice husk ash) should be used to reduce humidity accumulation inside the greenhouse. For weather with poor ventilation, smoke or powder-based agents (such as Bacillus subtilis smoke agent, sulfur fumigation) can be used to control gray mold, downy mildew, and other diseases.
• Pest and Disease Monitoring and Response: After the cold wave, plant resistance declines, making them more susceptible to soft rot, gray mold, and downy mildew. Health monitoring of plants should be strengthened, and low-toxicity, low-residue broad-spectrum fungicides such as Thiophanate-methyl and Chlorothalonil should be applied promptly to prevent disease spread. Simultaneously, frozen and dead plants should be removed to reduce the breeding sources of pathogens.

5. Scientific Management of Light and Prevention of Light Stress

Once the weather clears, the light management of vegetables should be gradually adjusted to prevent sudden exposure to strong light, which can cause wilting:

• Gradual Removal of Covering Materials: After sunny weather, the insulating cover of the greenhouse should be gradually removed to avoid excessive stimulation of photosynthesis, which may lead to plant dehydration and wilting. If plants show signs of wilting, the cover should be immediately replaced, and once recovery occurs, it should be slowly removed in cycles until the plants adapt.
• Adjust Environmental Humidity: After light recovery, small ventilation should be provided to dissipate fog and increase light transmission, preventing excessive humidity from causing diseases. A 1% seaweed acid solution or plain water can be sprayed at noon to alleviate plant water deficits and improve cold resistance.
• Open-field Management: For open-field vegetables, after the snow and ice melt, the coverings should not be removed immediately. The covering should be gradually removed after the day-night temperature difference stabilizes and the soil temperature rises to reduce frost damage risks.

6. Rush Harvest and Replanting to Minimize Economic Loss

To reduce the impact of the cold wave on vegetable production, harvest and replanting strategies should be optimized:

• Rush Harvest of Mature Vegetables: Before the cold wave arrives, vegetables that are already mature should be harvested as soon as possible to reduce losses. For vegetables that have been frozen but still have commercial value, they should be harvested and brought to market promptly to minimize economic losses.
• Handling of Frozen Crops: Severely frozen plants should be removed from the field immediately to avoid rotting and contamination of the soil. Vegetables with slight frost damage can be trimmed to remove damaged parts, which will promote recovery growth.
• Replanting Fast-Growing Vegetables: After the disaster, production should be quickly restored. Fast-growing, cold-resistant vegetables such as Chinese cabbage, lettuce, mustard greens, spinach, and chrysanthemum greens, which have short growing cycles and strong cold resistance, can be replanted to make up for losses and improve land utilization efficiency.