The freezing damage occurred during the seedling and returning stages of winter wheat has a great impact on the yield. The freezing damage in these two periods has frequently occurred in wheat production in Xinji and other places in recent years, causing large economic losses to farmers. If we can understand the causes of frost damage, take precautions and take measures after the occurrence of frost damage, we can minimize the damage caused by frost damage.
First, the main cause of frost damage in wheat
1. The reason for the climate. Due to global warming, the temperature of wheat before sowing and the temperature before overwintering are higher than in the past. As a result, some wheat grows too fast and the cold resistance weakens, causing freezing damage to wheat.
2. The quality of the site is poor. In recent years, the method of sowing wheat field sowing has generally adopted ploughing, rotary tilling, sowing, or directly using a rotary cultivator to spin plough twice and direct sowing. This kind of soil preparation method caused the soil to be loose, the water in the soil was seriously dispersed, and the heat capacity of the soil was small. After entering the winter, it caused freezing damage to the above-ground wheat leaves and roots, which was the main reason causing the large-scale cold damage of wheat.
3. Improper sowing date. In recent years, a large number of rural laborers have migrated from rural areas. After the harvest of autumn crops, regardless of the characteristics of wheat varieties, farmers sow seeds when they are solicited. Some sowing seeds need to be planted in advance, resulting in madness and prolonged growth in wheat years ago. The cold resistance is reduced. Cause a large area of ​​cold damage.
4. The use of nitrogen fertilizer is too large. Nitrogen fertilizer is an indispensable fertilizer for wheat growth, but excessive use and one-time application of basal fertilizer can easily cause seedlings to prosper, leaves are tender, and the tillers cannot store enough sugar, and they are susceptible to freezing injury during wintering.
Second, preventive measures
1. Based on the selection of cold-resistant varieties and fine soil preparation, timely repression after sowing and before overwintering, to achieve virtual reality, ground leveling, which can reduce water loss and increase the heat capacity of the soil, thus greatly reducing the occurrence of wheat freeze injury .
2. Cultivate strong seedlings. Prevent the seedlings from forming too early or planting weak seedlings too late. Avoid excessive use of nitrogen fertilizers. Nitrogen fertilizer is an indispensable fertilizer for wheat growth, but the use of too much can easily lead to prolonged seedlings, delicate leaves, can not store enough sugar in the tillering festival, winter susceptible to frost damage. If the above situation occurs, measures such as water control, suppression or deep plowing should be taken immediately to control their growth.
3. Strengthen management, freeze and protect seedlings. The first is winter irrigation. Pour well frozen water before winter to supplement soil moisture. Adequate soil moisture can stabilize low temperatures, seal topsoil, and reduce cracks and wind extraction. Winter irrigation should generally be carried out at a daily average temperature of about 3°C, when watering can be done in time. Sand land should be poured properly late, and clay ground and low-lying land should be properly poured. Water content in the arable layer can reach 80% or more of the field capacity without pouring. If the irrigation is too early, surface compaction will be formed, and the wintering tillering festival will be easy to be in the dry soil layer. If the irrigation is too late, surface ice will be easily formed and freezing disasters may occur.
4. Winter suppression. In the early winter sunny day, it can be crushed and repressed to crush the topsoil, seal the earth seams, reduce the cold wind and promote the increase of the lower layer of water, so as to lift, protect roots and prevent freezing.
5. Coverage. In winter, it is covered with soil miscellaneous fertilizer or comminuted straw, and after the growth of the wheat is stopped at the ground, the soil ridge on the field ridge can be covered in the wheat row, which can be heat-preserved to reduce the frost damage. After the return of green, it must be cleared and ridged. In order to prevent freezing, Qing ridge should choose cold tail warm weather.
6. Try to reduce the adverse effects of late spring on the return of green wheat. First, timely watering before the onset of the cold, because the specific heat of water is large, can ease the sudden drop in temperature and reduce hazards. Second, in the early morning before the onset of the cold current, in the field waterways and roadsides, more points of burning wood grass smoked, expelling the cold.
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