The Latest Methods for Preventing Low-Temperature Freeze Damage in Napa Cabbage

Winter temperatures are low, and cold air can also arrive suddenly, catching people off guard. Many people work hard for a whole season, only to see their harvest ruined by a single freeze. So how can you prevent napa cabbage from being damaged by cold? We bring you some prevention and control measures, hoping they can help you.

I. Low-Temperature Freeze Damage

1. Low-temperature damage

Low-temperature damage is also called chilling injury. It mainly occurs in the middle and late stages of head formation in autumn napa cabbage. When the temperature is below 10 degrees, napa cabbage grows very slowly, and once it is below 5 degrees it almost stops growing entirely. Therefore, in the north, because cold waves come early and the temperature drops rapidly, insufficient heat often leads to loose heads and low yield and quality.

2. Freeze damage

In the northern regions of our country in November, usually about two weeks before the harvest of autumn napa cabbage, cold waves or snow may suddenly fall, and the temperature stays below 0 degrees. At this time napa cabbage has not yet adapted, and because its water content is relatively high, the low temperature often causes ice to form in the intercellular spaces. When the temperature rises again, the water can return to the cytoplasm and the cells recover to normal. But if the temperature suddenly drops below 0 degrees, the leaves are difficult to restore after freezing, and normal freeze damage is severe.

II. Prevention and Control Measures

1. Hardening seedlings at the seedling stage

When raising seedlings for transplanting, after the seedlings have all emerged, the seedbed should be ventilated, and as the weather warms up the ventilation should be gradually increased to carry out low-temperature hardening of the seedlings, so as to improve the cold resistance of the young plants and help them adapt to a low-temperature environment.

2. Adding protective facilities

First, set up windbreaks, which can block cold wind. The spacing between windbreaks should be relatively close, generally about 2 times the height of the windbreaks. Second, dig trenches for planting and cover with plastic film. When transplanting vegetables in early spring, the trench-planting method can be used. The trench depth should exceed the height of the vegetable seedlings, and then plastic film can be laid over the trench. Note that when covering with film, do not press down on the seedlings, otherwise the tops of the seedlings will suffer freeze damage.

3. Temporary heating

When a cold wave arrives, simple coal stoves can be set up on frames in the seedling shed for temporary heating, so as to raise the temperature inside the shed and prevent freeze damage. However, open flames should not be used, to avoid causing a fire.

4. Watering

After the cold air passes, when the weather is clear, there is no wind or only a light breeze at night, and the temperature drops rapidly, especially when the ground surface temperature falls below 0 degrees and frost occurs, a large amount of well water can be poured onto the ground to raise the ground temperature.

5. Applying heavy winter fertilizer

Before overwintering, 1000-500 kg of pig and cattle manure or local mixed fertilizer can be applied per mu between the rows of napa cabbage. This can raise the ground temperature by 2-3 degrees and also serve the purpose of being applied in winter and used in spring.

6. Smoking

Before frost occurs, smoking in the field can effectively reduce and avoid frost damage. However, note two things: first, the fire and smoke should be somewhat dense, so that the smoke screen can basically cover the whole field; second, the ignition time should be appropriate, and it should be done in the upwind direction.

  The above is an introduction to how to prevent low-temperature freeze damage in napa cabbage. We hope it can help you. To learn more related knowledge, please stay tuned to us.