Causes and preventive measures of winter wheat seedlings in spring

Winter wheat dead seedlings refer to the freezing damage caused by wheat over winter and early spring due to low temperature, and it is one of the common disasters in wheat production. In order to achieve high yield and stable yield of wheat and achieve high quality and efficiency, it is necessary to ensure that the wheat mass is reasonable and there are enough acres of panicles, so it is particularly important to prevent the occurrence of wheat dead seedlings.

1 Analysis of the causes of winter wheat seedlings in spring

1.1 Internal cause. Mainly refers to the poor cold resistance of wheat itself. Spring wheat varieties with poor cold resistance are easy to die after cold damage, so in the selection of varieties, we must choose winter or semi-winter wheat varieties suitable for local cultivation.

1.2 External causes. Refers to external factors that cause wheat to die. Such as unfavorable climatic conditions, soil conditions or improper cultivation measures.

1.2.1 Unfavorable climatic conditions. During the winter, long-term low temperature or strong low temperature often causes wheat to die in winter, the lower the temperature, the heavier the freezing and killing phenomenon. In addition, if the temperature is high before winter, the temperature will drop sharply after winter, and wheat will not be cold-killed before winter.

1.2.2 Soil conditions. If the soil conservation ability is poor, the bottom sputum is insufficient, and the emergence of wheat after seeding is slow to form a thin seedling, the secondary roots are less, the resistance is poor, and the wintering seedlings are prone to occur. After the early spring wheat enters the greening period, the cold resistance is reduced. If it encounters a cold spring or sudden temperature change, it will easily cause freezing damage.

1.2.3 Improper cultivation measures. Grab the sowing, the bottom of the bottom is not enough, or the sowing is deep, forming a dry seedling, weak seedling; the amount of sowing is too large, the wheat field is long before winter; the sowing is too early, the amount of sowing is too large, the accumulated temperature before winter is too long, the wheat seedlings grow long, resulting in The group is too large, and there are many small cockroaches. When the temperature in spring is greatly reduced, it will cause freezing damage. It is difficult to form strong seedlings before winter sowing. After spring, the wheat is suddenly attacked by cold air and is also susceptible to freezing.

2 Defense measures

2.1 Watering. Since the heat capacity of water is larger than the heat capacity of air and soil, watering before the early spring cold current can increase the water vapor in the near-surface air, release latent heat when condensation occurs, and reduce the variation of the ground temperature. At the same time, the air humidity in the near-surface layer is also increased, and the direct invasion of the plant by the low temperature is alleviated. The survey found that irrigation before freezing can increase the ground temperature by 2-4 degrees Celsius, significantly reducing the degree of frost damage.

2.2 smoked. It can be used to burn firewood and smoked cigarettes in the fields, and can also emit CHN chemical smokers. The heat emitted by the smoke screen can raise the temperature and slow the direct invasion of the wheat tiller. The time of fumigation is generally reduced to 1 degree Celsius above the frost index, and the cigarette time should be uniformly released when the smoke is smoked to ensure the quality, in order to receive good results.

2.3 Strengthen cultivation management and improve the ability of wheat to resist freezing. 1) Choose winter and half-winter wheat varieties with strong cold resistance. Because the cold-resistant varieties have the ability to resist cold, or can quickly restore growth after the disaster, they can prevent freezing and seedling, and reduce the occurrence of winter and spring dead seedlings. 2) Timely late broadcast can delay the lifting and unwinding of wheat to protect it from freezing damage. Improve the quality of the land preparation, carry out fine arable land before sowing, pour the collapsed water, prevent the cold wind from invading, cultivate the strong seedlings before winter, timely winter irrigation, keep the seedlings safe and winter, and strive for the spring management. 3) Early spring cultivating land can be suppressed. The cultivating plan can effectively compensate the surface cracks, prevent running, and play the role of warming and protecting the roots, and can promote the growth of secondary roots. Repression can not only inhibit the growth of the upper part of the earth, but also strengthen the soil and improve the sensation, so as to achieve the purpose of reducing frost damage. 4) Rational fertilization according to seedlings. Fertilization of excessive nitrogen fertilizer, the plant is prone to freezing damage, in order to prevent freezing damage, more phosphorus and potassium fertilizer should be applied. The frozen wheat field can be sprayed with plant growth regulators such as Fengbiling and Huafu to enhance the cold resistance and stress resistance of the plants.