Occurrence and remediation of the latest spring frost injury of wheat

In February and March of every spring, cold air often breaks out to the south in the north, and the process of cooling is large, and the wheat jointing prematurely often suffers from freezing injury. At this time, for overgrown seedlings, measures should be taken to suppress their growth; to reasonably fertilize and promote the weak seedlings to become strong, so as to enhance their ability to resist cold; at the same time, we should pay attention to listen to the weather forecast and irrigate water before the cold wave comes. or organize a large area of unified fumigation, in order to prevent and reduce frost damage.

Wheat is not tolerant to cold after jointing.

Wheat is a relatively low temperature tolerant crop, but its cold resistance is related to its developmental stage. In the seedling stage, the cold resistance was the strongest in the "vernalization" stage, and further decreased after the completion of "vernalization". When the freezing injury occurs, under the action of low temperature, the water in the wheat cell tissue will freeze. When the wheat cell freezes, the volume will increase and the cell will be damaged. If the temperature further drops, the cell will also freeze, resulting in death. After jointing, the young spikes may freeze to death or form abnormal spikes when they meet the low temperature of-1 ℃-4 ℃. The greater the extent and steepness of the cooling process, the longer the duration of low temperature, the more serious the damage.

Check the degree of damage after freezing

The damage degree of wheat should be checked in time after freezing, and the focus of the inspection is on young spikes. Where the young ear frozen to death of the plant, the heart leaf no longer elongate, most rolled into a trumpet shape, a few directly withered and died. However, some frozen plants give people a false impression, the leaves can still remain turquoise, and some even do not wither until 10-15 days later, so it is necessary to further peel off the young ear, if it is found that the young ear is milky white and opaque, it is already frozen to death.

Remedial measures

1. Don't plough the frozen wheat fields at will. Spring frost injury occurs in spring, when the root system of wheat seedlings is well developed and the tillering nodes are relatively sturdy. Even if all the aboveground parts of the plant freeze to death, the roots and tillers will not die. As long as the management is strengthened, with the same rise of air temperature, new tillers will soon grow and still be able to spike and bear fruit.

2. Do not cut frozen yellow leaves and "dead tillers". The study shows that after wheat is frozen, the fertilizer absorption capacity of the root system of "dead tiller" is stronger than that of living tiller within a certain period of time. After the main stem and large tiller are frozen to death, the nutrients absorbed by the root system can be transferred to the living tiller. This is very good for frozen wheat seedlings to restore vitality and increase tillers into spikes.

3. Topdressing and watering. After the wheat is frozen, the nutrient consumption in the body is too much, and the seedling potential is very weak. With the rise of the temperature, new stems and tillers grow rapidly, which requires a lot of water and nutrients. Timely watering, topdressing, and topdressing urea 5-7.5 kg / mu according to the seedling condition, or foliar spraying 1% 2% urea solution to promote the recovery of growth.