Heavy rainfall cools down! How does wheat deal with "cold spring"? Experts from the Ministry of Agriculture and Rural Affairs teach you to take precautions.

Rain and snow occurred in many places in the north, heavy rainfall occurred in many places in the south, and large-scale precipitation began in the central and eastern regions. According to the forecast of the Central Meteorological Observatory, from 16 onwards, there were frequent rains and cooling weather from north to south, with the cumulative decline in many places in the central and eastern regions exceeding 20℃.

According to the weather forecast of 17, the rainfall is still decreasing. There are small to moderate rains in parts of central and northern Shaanxi, central Henan, southern Shandong, Jianghuai, most of the south of the Yangtze River, most of southern China, southeastern Southwest China and Taiwan Province Island, among which there are heavy rains in parts of central and southern Jiangsu, southeastern Anhui and Shanghai.

In addition, the temperature drop in southeast Henan, south-central Anhui, southwest Jiangsu and northeast Hubei can reach more than 12℃.

It can be seen from the rainfall and cooling forecast map that many wheat planting areas are included in the range of heavy rainfall and strong cooling. According to people in the meteorological industry, the cooling phenomenon in many places has met the definition of "late spring cold", and it can basically be judged that many areas have formed "late spring cold".

"Late spring cold" is bound to affect the normal growth of wheat. In view of this, the wheat expert guidance group of the Ministry of Agriculture and Rural Affairs gave some guidance on how to scientifically prevent "late spring cold".

Details are as follows:

First, understand the harm of "cold spring"

Late spring cold usually occurs in March-April. According to the growing period of wheat, it is often encountered from jointing stage to booting stage.

At the jointing stage of wheat, if the surface temperature drops below minus 2 degrees, the main stems and big tillers of wheat will easily freeze to death, and the yield will be reduced by about 10%-30%. If the temperature drop is large, the main stems and tillers will freeze to death too much, and the yield will be reduced by more than half.

At the booting stage of wheat, if the surface temperature drops below 0 degrees, it will affect the development of spikelets and florets, from "half-ear" to "no grain in ear" or even no grain in ear.

When the number of wheat ears decreases, the number of grains per ear decreases, and the 1000-grain weight decreases, the yield is also reduced.

Second, how to prevent the harm of "late spring cold"

1. For the wheat fields that are in the turning green stage and have not yet started jointing stage, soil cracks can be filled by soil suppression, so as to make the root system of wheat more closely combined with soil, prevent drying and water loss, thus improving the cold resistance of wheat itself and reducing the harm of "late spring cold".

2. For the wheat fields that have not yet entered the jointing stage, if the wheat grows vigorously, it is also necessary to control the growth of wheat to improve the resistance and promote the normal growth.

On the basis of the first point, chemical agents such as Zhuangfeng 'an and paclobutrazol can be sprayed for chemical control treatment, which not only improves the cold resistance, but also reduces the probability of subsequent lodging.

3. For normal growing wheat, brassinolide and leaf fertilizer of medium and trace elements can be sprayed before cooling to improve the cold resistance of wheat and reduce the harm of "late spring cold".

4. For wheat fields with dry soil, irrigation and watering can be carried out before the cooling comes, which can adjust the microclimate of soil and near-surface layer, reduce the amplitude of ground temperature and buffer the influence of cooling on wheat.

Third, how to remedy the influence of "late spring cold" on wheat?

1. If the wheat suffers from "late spring cold" at jointing stage, and freezing injury occurs, observe the degree of freezing injury of young ears of wheat within 2-3 days after freezing injury.

If the freezing rate of leaves or young spikes of main stems is less than 10%, there is no need for excessive management. After the temperature warms up, wheat grows normally, which has limited impact on yield.

If the freezing rate reaches 10%-30%, an acre of land can be topdressed with about 5 kg of urea; If the freezing rate reaches about 30%-50%, 7-10 kg of urea can be topdressing one mu of land; If it exceeds 50%, it can be topdressing 12- 15 kg of urea.

The purpose of topdressing urea is to promote the continuous growth of wheat seedlings that have not been frozen to death and reduce the losses caused by freezing injury.

2. If wheat suffers from "late spring cold" before and after booting stage, 3-4 kilograms of urea can be applied to one mu of land, or potassium dihydrogen phosphate and brassinolide can be sprayed with pesticides and fungicides, which is beneficial to increase the number of grains per ear and increase the grain weight.

The above is about how to prevent the "cold spring" of wheat. According to the weather forecast, the rain and cooling will last until the end of March.

Therefore, for wheat growers, more attention should be paid to the growth of wheat after cooling. If there is freezing injury, you can go topdressing or spraying plant growth regulators until there is no rain at noon and the temperature is suitable.

To prevent the "cold in spring" of wheat, we should follow the principle of "prevention first, combining prevention with rescue, and promoting growth with fertilizer and water", strengthen management, reduce harmful losses, and go all out to promote a bumper harvest of summer wheat.