Occurrence and remedy of Frost injury in Spring of Wheat

In February and March of every spring, cold air often erupts southward in the north, and the cooling range is large in the process. The wheat that jointing prematurely often suffers from freezing injury. At this time, for the seedlings that grow too much, we should adopt suppression methods to inhibit growth; rational topdressing of weak seedlings, promotion of weak and strong, in order to enhance cold resistance, at the same time, we should pay attention to listening to weather forecasts, irrigation before the arrival of cold waves, or organize large-scale unified smoking, in order to prevent and reduce freezing damage.

Wheat after jointing is not cold resistant

Wheat is a relatively low temperature tolerant crop, but the cold resistance of wheat is related to its development stage. At seedling stage, cold resistance was strongest at vernalization stage, and decreased further after vernalization. When freezing occurs, under the action of low temperature, the water in wheat cell tissue will freeze, when the ice between cells increases, the cell is damaged, if the temperature drops further, the cell will freeze, resulting in death. After wheat jointing, when it encounters low temperature of-1℃-4℃, young ears may be frozen to death or form abnormal ears. The greater the amplitude and steepness of cooling process and the longer the duration of low temperature, the more serious the harm will be.

Post-freeze inspection of damage

After the wheat is frozen, the damage degree should be checked in time, and the focus of inspection is on the young ears. Where the young panicle freezes to death the plant, the heart leaf no longer elongates, most rolls into the trumpet shape, a few directly withers and dies. However, some frozen plants give false appearance, the leaves can still maintain green color, and some even to 10-15 days later before wilting, so to further peel the young ears to see, such as the young ears were found milky opaque, that is, frozen to death.

remedies

1, frozen wheat fields do not plow at will. Spring frost damage occurs in spring, when the root system of wheat seedlings is already very developed, tiller nodes are also relatively strong, even if the aboveground part of the plant is completely frozen to death, root system and tiller will not die, as long as the management is strengthened, with the same temperature rise, new tillers will soon grow, and still heading and bearing fruit.

2, frozen yellow leaves and "dead tillers" do not cut. The results showed that after freezing, the root system of "dead tiller" had stronger ability to absorb fertilizer than that of live tiller in a certain period of time. After the main stem and big tiller were frozen to death, the nutrients absorbed by the root system could be transferred to the living tiller, which was beneficial to the recovery of vitality of frozen wheat seedlings and the increase of tillers into ears.

3. Topdressing and watering. After freezing, the nutrient consumption in wheat is too much, and the seedling potential is very weak. With the rise of temperature, new tillers grow rapidly, which requires a lot of water and nutrients. It is necessary to water and topdress in time, and apply urea 5-7.5 kg/mu according to the seedling situation, or spray 1%-2% urea solution on the leaves to promote the recovery growth.