What should be done to deal with the freezing injury of wheat at heading stage?

For winter wheat, which wheat is prone to freezing injury? What measures should be taken after frostbite? Let's take a look with everyone!

First of all, the conditions that winter wheat is prone to freezing injury

Temperature: Winter (late February of 65438 to mid-February of the following year) sustained low temperature or winter abnormal weather caused by alternating freezing and thawing caused by wheat freezing injury.

After wheat is sown, the temperature remains high until winter begins, and then it suddenly cools down, such as snowfall and rainfall. The low temperature drops about 10℃ and reaches below-10℃ for 2~3 days. Wheat seedlings have not been cold-resistant and have poor frost resistance, and it is easy to form early winter (165438+).

When the average temperature for more than two months in winter is more than 2℃ lower than normal, there are more days with the low temperature of-15~ 13℃, which is prone to long-term low-temperature freezing injury in winter.

During the overwintering period (from the end of 65438+February to the middle of February of the following year), wheat was dormant and had strong cold resistance. However, due to the uninterrupted growth of wheat in Huanghuai sea area in winter, wheat is in the growth stage of aboveground and underground parts at this stage. Once encountering warm weather, the seedlings begin to grow again, and their cold resistance is relatively weakened. When the cold current cools down to-15~- 13℃ again, it will cause serious freezing damage in winter.

Wheat seedlings: The types of frozen wheat are weak seedlings and strong seedlings. The rapid growth of wheat seedlings in the early stage will lead to large field population, weak seedlings and poor disease resistance and stress resistance. If you encounter low temperature during wintering, it is easy to cause freezing injury, pests and diseases, and easy to suffer losses. Moreover, if the seedling population is too large, it will produce many ineffective tillers, consume nutrients, bear no fruit and affect the yield.

Cultivated land: Wheat fields with poor soil preparation quality in the early stage, especially wheat fields and sandy wheat fields that have not been suppressed by rotary tillage in recent years, have frozen seedlings every winter. In the case of poor soil moisture, serious freezing damage can also be formed. In addition, the plots with shallow plough layer, crop roots exposed on the surface or too deep sowing, and weak wheat seedling growth are easy to cause freezing injury.

Variety: The development characteristics of different wheat varieties are quite different, the development process is fast or slow, and the degree of freezing injury is also different. There are great differences in frost resistance and cold tolerance among wheat varieties. Generally speaking, the order of frost resistance of wheat is: 1. Winter varieties; 2. Weak spring varieties; 3. Spring varieties.

Second, the characteristics of wheat freezing injury in winter

The external symptoms of frostbite in winter are obvious. At first, some or all the leaves were flooded, and then gradually dried up and died. The size of the dead area of leaves depends on the degree of freezing damage. The heavier the freezing damage, the larger the dry area of leaves, which is the basis for the division of freezing damage in Huanghuai sea area in the past. However, our experts also reminded our farmer friends not to panic. In early winter and overwintering period, the freezing injury generally shows that some leaves are damaged by freezing. Even if the symptoms of leaf tip yellowing appear, as long as the growing point is not frozen, it will not have a serious impact on the later growth and yield of wheat!

Third, how to carry out prevention and control in the later period.

Because the growing season of wheat seedlings is generally concentrated in spring, that is, in March and April of the following year, the temperature suddenly drops during this period, even if it causes slight freezing damage, it will not have a great impact. Farmers' friends must correct their mentality, prescribe the right medicine, and don't go to the doctor for illness, but do bad things.

1, to suppress Wang Miao.

Now is a good time to suppress Wang Miao. You can sprinkle a proper amount of quicklime in Wang Miao, which is hygroscopic. It has the functions of disinfection, sterilization and pest control, but it also has a little-known benefit, that is, it increases the available nitrogen in the soil (usually used before turning over the soil) and increases the release of organophosphorus. There is also a foliar fertilizer that can be sprayed.

2. Remedy after the year

① topdressing nitrogen fertilizer in time to promote the rapid growth of small tillers. In the wheat fields where the main stems and big tillers have been frozen to death, the jointing stage of wheat turning green should be combined with watering and applying jointing fertilizer and urea 10- 15 kg/mu.

② In general frozen wheat fields, only leaves are frozen and withered, and there is no tillering phenomenon. Early remedial application (spraying potassium dihydrogen phosphate+brassinolide) should be carried out in early spring to promote the greening of wheat seedlings; Topdressing and watering at the rising stage can improve tillering rate.

③ Strengthen the management of fertilizer and water in the middle and late period to prevent premature senility. Frozen wheat fields are prone to premature aging in the later stage because plants consume more nutrients.

On the basis of the first topdressing in spring, according to the growth and development of wheat seedlings, according to the needs of wheat seedlings, an appropriate amount of foliar topdressing was carried out at jointing stage or flag-raising stage to promote large panicles and more grains, improve grain weight, and strive to minimize freezing damage and improve wheat yield in that year.