When the weather turns cold, cucumbers get cold easily. How to remedy after freezing?

The reason of cucumber freezing is that the temperature is too low, which causes freezing injury. When the temperature of the environment around the main stem of the seedling decreases to the extent that the aqueous solution in the intercellular space of cucumber seedlings produces ice crystals, the water content decreases and the solution concentration increases, which leads to the capture of water in the cell, the loss of water in the cell fluid and the freezing in the intercellular space. Because the volume of ice is larger than that of water, it is accompanied by the continuous expansion of ice bodies between cells, squeezing cells. It is destroyed by mechanical equipment and protoplasm in cells. At the same time, due to the lack of water in cell fluid, protoplasm aggregation will cause freezing injury, causing partial or total withering or death.

The sudden drop in temperature is easy to cause frostbite. Under the condition of slow cooling, the flour of seedling body is converted into sugar under hydrolysis. Because sugar is soluble in water, it can increase the concentration of cell fluid, so the cold resistance of seedlings is gradually improved. If the climate changes suddenly, the temperature will suddenly drop a lot, because the wheat flour contained in the seedlings can not be converted into sugar as much as possible, and the seedlings are very vulnerable to freezing injury.

The lowest temperature for all normal development of cucumber is 10℃ ~ 12℃. When the temperature is lower than 10℃, physiological activities such as photosynthesis, photosynthesis, the operation of photosynthetic products and fertilization will be damaged or even stopped. The main stem of cucumber is tender, and generally -2℃ ~ 0℃ is the cold death temperature. However, the adaptability of cucumber to lower temperature is often different due to the order of cooling and the level of ultra-low temperature exercise. The main stem without ultra-low temperature exercise will suffer from chilling injury at 5℃ ~ 10℃ and die of cold at 2℃ ~ 3℃.

Cucumber suffered from freezing injury in the growth process, and the following countermeasures should be taken to save it:

Pruning dead branches: immediately prune frozen leaves and stems to prevent mildew and diseases, resulting in pests and diseases.

Manual watering: Sprinkling water can improve the relative humidity of air in the arch shed, stabilize the shed temperature and reduce the evaporation of water surface when the freezing mechanism slides and dehydrates.

Watering: After the cucumber is frozen, it is not allowed to close the shed to raise the temperature immediately, but only water the flowers to lower the temperature, so that the temperature of the arch shed will rise slowly and prevent the freezing mechanism from shrinking due to the sharp rise in temperature.

Water injection for thermal insulation: Water injection can improve the thermal conductivity of soil layer, avoid soil temperature drop and stabilize the near-surface temperature. This is beneficial to the steady rise of temperature and the repair function of freezing mechanism.

Shading in shed: An arched shed was set up to shade cucumber, so as to avoid being exposed to sunlight after freezing and alleviate the water shortage of freezing mechanism.

Topdressing: After the emergence of the main stem is delayed due to freezing injury, topdressing and quick-acting fertilizer should be applied. Spray the leaves with 2% urea solution or 0.2% potassium dihydrogen phosphate solution.