Extremely cold weather may occur again this winter. Appropriate cold and cold is beneficial to wheat growth, but extremely cold weather will cause freezing damage to some wheat, affecting wheat growth and later yield. Therefore, it is necessary to prevent wheat frost damage.
Wheat frost damage refers to the stagnation of wheat growth caused by continuous low temperature weather in wheat fields. After freezing, the lighter wheat field, the main stem of the wheat plant and the young ears of the big tiller were still frozen and still normal heading and fruiting; however, the number of kernels was significantly reduced.
When the freezing damage is heavy, the main stem, the big tiller, the young panicle and the heart leaf are frozen to death, and the rest can still grow; the wheat leaves and leaf tips of the wheat field with severe freezing damage are hard and brittle, and the green leaves are dry or blue and green. Stems, young ears shrink and die.
The main factors leading to the occurrence of wheat freezing damage
Wheat varieties, sowing date, sowing amount, climatic factors, seedling conditions, lyrics, and planting quality of the land will all affect the occurrence of wheat frost damage. The main wheat fields that are susceptible to freezing damage are:
1. Sowing seedlings that are too early;
2, the group is too big and long seedlings;
3. Wang Changmiao with excessive nitrogen fertilizer;
4. Extensive grounding and overhead hanging seedlings;
5. Seeding too shallow seedlings;
6. Dehydration seedlings caused by soil drought;
7. Weak seedlings caused by freezing damage;
8. Yellow thin and weak seedlings with insufficient soil fertility.
9, straw returned to the land, poor treatment of weak seedlings.
Wheat freeze damage is divided into four levels
The primary freezing damage is mild frost damage, mainly manifested by the tip of the upper 2~3 leaves or less than 1/2 of the leaves being frozen and yellowed;
The second and third grade freeze damage mainly manifests that more than half of the leaves are frozen and yellow;
The fourth-grade freeze damage is severely frosted. The main manifestation is that more than 30% of the main stems and large tillers are frozen. They have been jointed, and the stems are partially frozen and cracked. The young ears lose water and even die.
How to prevent wheat frost damage
1. Choose anti-freeze varieties, sow seeds in a timely manner, and cultivate strong seedlings.
2, early topdressing. Wheat fertilization in early spring can make up for winter soil fertility consumption, increase nutrient accumulation, promote the growth of wheat seedlings, and resist or reduce early spring frost damage, especially in the years when winter temperatures are high, wheat seedlings continue to grow, and soil fertility is high. Fertilization in early spring is especially important.
3. Timely strokes to promote growth. When the soil is re-slurry, the topping is carried out, which can play the role of loosening soil, protecting the mites, warming and weeding, and enhancing the ability of the wheat seedlings to protect against cold.
According to the experience of the past years, the average ground temperature in the 5 cm soil layer during the day can be increased by 0.5 to 1 °C after 7 to 10 days, which is beneficial to the promotion of root development and nutrient conversion.
4, suppression and control, to ensure the steady growth of wheat. In the early spring, the wheat field can be crushed, and the cracks can be crushed to close the cracks, so that the wheat roots are in close contact with the soil, preventing cold air from invading and damaging the wheat seedlings.
At the same time, the suppression also has a lifting effect, which can increase the water content of the soil surface layer, and is beneficial to alleviate the low temperature chilling damage.
5, watering at the right time. Watering ahead of the cold current according to weather forecasts is an effective way to prevent or mitigate night frost damage. Watering can increase the humidity of the air near the plant, increase the dew point temperature, and easily cause the moisture to condense and release latent heat.
According to the experience of the past years, it is best to pour water in the first 5 days before the frost;
Watering within 5 to 10 days before frost will suffer from different degrees of freezing damage;
There is almost no antifreeze effect when watering for more than 10 days before the frost.
Wheat fields without watering conditions can be smoked and frosted in time when the cold current arrives, and there is also a certain antifreeze effect.
6. Strengthen post management. In the period of wheat returning to the body, the use of 15% paclobutrazol wettable powder 50-60 grams per acre, evenly sprayed, can inhibit the growth of wheat seedlings and enhance cold resistance. At the same time, strengthen the prevention and control of diseases, insects and waterlogging in the middle and late stages of wheat fields, prevent premature aging, and capture the harvest.
Main remedies after wheat freeze damage
1, timely topdressing, increase nutrition. After the soil with poor fertility is thawed in the field, 5 kg of urea and 2 kg of diammonium phosphate are applied per mu, preferably the ditch.
2. In the period of wheat greening and jointing, 10 kg of urea per mu is combined with pouring and water saving, and 400 g of potassium dihydrogen phosphate + 0.01% of Tianfengsu 10 ml of foliar spray per acre is used for prevention and control;
3, early spring and early strokes, improve the ground temperature, promote the return of wheat seedlings, improve the rate of tillering. Pay attention to the spraying and spraying before 15:00 in the afternoon after 10:00 in the morning. It has good control effect and therapeutic effect. The specific medication should be determined according to the actual situation of each household.
Measures taken in time after the year
1. Apply nitrogen fertilizer in time to promote the rapid growth of small tillers. The main stem and the large tiller have been frozen in the wheat field, and the wheat is fed back to the jointing stage to combine the watering and fertilizer application, and the urea is applied at 10 kg/mu.
2, generally affected by frozen wheat fields, only the leaves are frozen and dead, no dead cockroaches, early spring should be similar to the pre-winter remedy application (see above), to promote the return of wheat seedlings; in the rising period of topdressing watering, improve the tillering rate .
3. Strengthen the management of fertilizer and water in the middle and late stages to prevent premature aging. The frozen wheat field is prone to premature aging due to the consumption of nutrients in the plant.
On the basis of the first top dressing in spring, look at the growth and development of wheat seedlings, according to the needs of wheat seedlings, in the jointing stage or picking the flag period, the appropriate amount of foliar topdressing, promote the increase of grain size, increase the grain weight, and strive to reduce the damage of freezing damage to a minimum. To increase the annual output of wheat.
As wheat grows faster, the ability of wheat to withstand cold is reduced. The sudden drop in temperature is a significant feature of current temperature changes, which will have varying degrees of impact on wheat production. To this end, we must pay close attention to climate change, strengthen field management, correctly prevent wheat early spring frost damage, and ensure that summer grain increases production and income.
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