Cold current and cold weather are the biggest threats to the success or failure of watermelon cultivation in cold season. How to prevent watermelon from freezing injury?

Watermelon is a kind of crop that likes temperature and is heat-resistant. Low temperature, especially at night, is the most unsafe factor in greenhouse production, and it is the main restrictive factor that causes chilling injury and freezing injury and affects the growth and development of watermelon. How to prevent freezing injury and cold injury is a systematic project.

(1) Building a greenhouse facility with external thermal insulation protection layer, complete cold ditch inside, brick-wrapped composite hole wall, internal support and external pressure, reasonable structure, high light transmittance, rapid temperature rise and good thermal insulation performance is the primary condition for successful greenhouse overwintering cultivation.

(2) Improve the resilience and self-protection of crops. Crops can have strong resistance to cold and freezing, which is of special significance for overwintering cultivation in greenhouse to resist cold injury and freezing injury. The methods to improve the stress resistance of crops are as follows:

(1) Select varieties with low temperature tolerance and strong stress resistance.

(2) Exercise at low temperature when watermelon seeds germinate to improve the adaptability of seedlings to low temperature.

③ Use "Tianda -2 1 16" to irrigate the roots, coat the stems and spray the plants continuously to improve the frost resistance and low temperature resistance of watermelon plants.

(3) Ridge planting should increase the surface area of soil, so that the soil can absorb more heat, raise the temperature quickly, increase the ground temperature, make the hot soil layer thick, and accumulate more heat. High soil temperature is conducive to the development of watermelon root system, improve root activity, and achieve the goal of deep root growth and prosperity. Moreover, higher soil temperature can release more heat at night, stabilize the temperature at night and reduce the occurrence of freezing injury. Generally, the ridge height should reach about 25 cm.

(4) Covering the whole area with plastic film can increase soil temperature, inhibit soil moisture evaporation, reduce greenhouse heat loss, and improve and stabilize greenhouse temperature. It is not only an effective measure to reduce indoor air humidity and diseases, but also one of the most effective measures to improve and stabilize indoor temperature, maintain heat balance and prevent crop freezing injury.

(5) Tightly sealed to eliminate heat dissipation from pores.

(6) Improve the thermal insulation quality of opaque coating. Minimize the night heat dissipation of the lighting surface.

(7) Ignition and heating. For detailed methods, please refer to "What can I do to improve the temperature in the greenhouse and effectively prevent freezing injury and freezing injury?"

(8) Try to increase the indoor temperature during the day. After entering the severe winter season, as long as the indoor temperature does not exceed 35 degrees, ventilation is prohibited during the day to maintain and stabilize the temperature in a high range. Use high temperature to raise soil temperature, and use high soil temperature to stabilize indoor temperature at night to prevent low temperature injury.