Since entering the spring, the weather has become warmer and warmer, but there are still cold air coming from time to time. It is commonly called “cold spring”, and the high and low temperature will cause great harm to the growth of crops. Then what measures should be taken to deal with the "cold spring"?

⊙ fruit tree

Due to the frequent and unexpected occurrence of night frost in recent years, it has caused great harm to fruit tree production. Although we can't control the change of natural temperature, the following measures can effectively avoid and mitigate the damage caused by night frost damage to fruit trees.

1. Pay attention to weather changes and raise awareness of prevention

The night frost damage of fruit trees should be based on prevention. The frequent and variable cold currents in spring in northern China are the climatic phenomena that occur every year. Therefore, it is necessary to set up your own temperature and ground temperature observation records in the park, and pay attention to the weather at any time. Changes and weather forecasts, especially before the fruit tree sprouts, on the basis of understanding the long-term weather forecast of the local meteorological department, pay attention to the short-term weather forecast of the flowering period, predict the time and intensity of the frost, and take emergency precautions early.

2. Select a microclimate environment that is conducive to fruit tree growth

First, choose an appropriate microclimate environment to build a garden. The correct selection of the site is an effective anti-freezing measure for the orchard. If the park should choose the southward or southeast slope of the leeward sun, avoid building a garden in low-lying areas and closed valleys. The second is to create a shelterbelt in the main wind direction of the orchard. The shelterbelt can not only effectively prevent wind, but also raise the ground temperature and prevent frost in early spring.

3. Emergency anti-frost measures

1. Smoke and anti-frost. The fumigation method is currently the most widely used method. The book "Qi Min Yao Shu" of the agronomic masterpiece summarizes the experience of preventing orchard damage in the orchard: "often in the orchard, the grass is stored on the grass, the manure is dry, the weather is new and the weather is cold, and the north wind is cold. At this time, who will set fire, if it is less smoke, it will be free from frost." The preventive effect depends on the quality of raw smoke, and the quality of the orchard is about 2 °C. The number of smokers is at least 5-6 piles per acre, evenly distributed in all directions. The grass pile is 1.5 meters high and the bottom diameter is 1.5 to 1.7 meters. When the grass is piled up, several thick wooden sticks are inserted straight and obliquely, and the venting holes are taken out after the smashing. The flammable material is placed inside the haystack by a hole, and the grass is covered with a layer of wet grass or wet mud. This amount of smoke is sufficient and lasts for a long time. The fumigation material can be used as a flammable material or a hooding agent (three parts of ammonium nitrate, 8 to 10 parts of sawdust, and 3 parts of diesel oil) which can generate a large amount of smoke such as straw, weeds, and fallen leaves.

2. Immerse and whiten in early spring. In areas where frequent night frost occurs frequently, measures such as early spring irrigation and whitening of trees can reduce tree temperature, delay sprouting and flowering, and avoid frost damage.

3. Irrigation and watering of the orchard before the frost. The irrigation of the orchard not only increases the soil water content, but also increases the heat capacity and thermal conductivity of the soil. The temperature decreases during the day and the temperature rises at night. The air close to the ground will not be hot and cold, and the temperature will be extremely strong. Regulation. Therefore, before the occurrence of low temperature, orchard irrigation can prevent and slow down the damage of frost. It is observed that the temperature of the tree after irrigation can be 1 °C ~ 2 °C higher than that of non-irrigation at night. The crown sprays water, and the water is condensed into ice, releasing latent heat, which can raise the temperature and alleviate the frost damage.

4. Spray chemicals and fertilizer before flowering. Before the flower, spray the Tianda 2116, the plant disease 863 inhibitor and other plant cell membrane steady-state agents and Bao Lifeng and other membrane amino acid series micro-fertilizer, increase the toughness of the cell membrane and improve the cold resistance of the tree. At the initial flowering stage, spraying potassium dihydrogen phosphate, amino acid calcium, borax, etc., can increase the cell liquid concentration of flower, young fruit and shoots, enhance the anti-freezing ability, and at the same time have the effect of fertilization.

Strengthening cultivation management and improving tree resistance

1. Choose a variety that is resistant to low temperature. Generally, late-maturing varieties are more resistant to freezing, and varieties with the ability to produce buds are also more resistant to freezing.

2. Reasonable load. Excessive load, not only reduce the quality, can not sell a good price, but also cause the fruit tree new shoots are not mature or mature, thin and emptiness, extremely cold-resistant.

3. Scientific fertilization. Generally speaking, no matter the seedlings or the result garden planted in the same year, avoid applying nitrogen fertilizer in early spring to prevent excessive growth; increase the application of phosphorus and potassium fertilizer, spraying lime, potassium sulfate and growth inhibiting substances on the foliage to promote the fullness of shoots and control autumn. The formation of shoots is prolonged or prosperous; after harvesting, organic fertilizer should be added to enhance tree potential and nutrient accumulation, and to improve antifreeze ability.

4. Strengthen the trimming. It is necessary to strengthen the pruning of the growing season. For example, the growth ability of the new shoots of the grapes is extremely strong. If the heart is not topped, it can grow indefinitely until the autumn. Such new shoots are not full and are not resistant to freezing. In order to prevent freezing, it is also a good harvest for the next year. It is necessary to pick up the new shoots of the grapes in time and repeatedly, so as to cultivate new shoots with large and thick leaves, full buds and mature branches, which not only has strong results in the next year, but also is extremely resistant to freezing.

5. Control pests and diseases. Pests and diseases seriously affect the maturity of new shoots and the quality of shoots and leaves. It is necessary to prevent and control, so that the tree production can accumulate more photosynthetic products, enhance tree potential and improve resistance.

V. Innovative cultivation mode

With the frequent damage of night frost, some tree species with high output value and suitable facilities, such as large cherry, peach, plum, apricot, grape, etc., should increase the scale of facility cultivation, so as to effectively avoid the night frost while increasing the output value. Hazard.

In addition, the orchard adopts new technologies such as grass, grass covering and sprinkler irrigation, and the effect of reducing night frost damage is also significant.

⊙ wheat

Type of frost damage

At present, the types of frost damage affecting wheat production mainly include winter frost damage, early spring frost damage (cold spring cold) and low temperature chilling damage.

1. Winter frost damage. Winter frost damage is the freezing damage caused by the cold wave during the winter after wheat enters the winter season.

2. Early spring damage (falling cold). Early spring frost damage refers to the period when wheat has entered the period of rejuvenation and jointing in the “Spring” season. Due to the cold wave coming to cool down, the surface temperature drops below 0 °C, and the frost damage occurs. Because the climate has gradually warmed up and suddenly came to the cold wave, it is also called the cold spring. In the wheat field where the early spring frost damage occurs, the leaves are soaked in boiling water and dried up after being exposed to sunlight. The young cells of the young shoots on the top of the stem are more sensitive to low temperature than the leaf cells. The degree of freezing of young ears varies according to their developmental process. Generally speaking, they have entered the stamen and pistil differentiation stage (jointing stage) and are susceptible to freezing, the young ears are atrophied and deformed, and finally dried up; while in the floret differentiation stage or the double-edge stage The young ears (from the beginning) are still transparent crystals after freezing and are not frozen to death. This is why the wheat field often shows that the main stem is frozen to death, the tiller is not frozen, or a part of the ear is frozen, and the late sowing wheat is lighter than the early sowing.

3. Chilling damage. Wheat grows into the booting stage, and the damage caused by the low temperature above zero is called low temperature chilling. The reason why wheat suffers from low temperature chilling injury: after the jointing of wheat to the flagging stage of the booting stage, the ability to resist low temperature is greatly weakened when the water content is high and the tissue is young. Before and after the development of wheat spikes to the tetrad formation stage (booting stage), the average daily temperature is required to be between 10 ° C and 15 ° C. At this time, it is extremely sensitive to low temperature and water shortage, especially to low temperature. If the minimum temperature is lower than 5 °C-6 °C will suffer. The characteristics of low temperature chilling injury in wheat are that the stems and leaves are not affected by the damage, and there is no abnormal performance. The damaged part is all or part of the spikelets of the ear, which is characterized by delayed heading or extraction of empty white spikes, or partial spikelets in wheat ears. Oh, only part of it is strong, which seriously affects production.

Frost damage prevention measures

1. Select suitable varieties. In areas where freezing damage occurs frequently, the area of ​​semi-winter varieties with better cold resistance and late jointing should be appropriately increased. In particular, dryland wheat should control the area of ​​weak spring varieties and prevent frost damage.

2. Strictly control the appropriate sowing date. The best sowing date for winter wheat is October 8-12, and the best sowing time for weak spring varieties is October 15-20.

3. Watering at the right time. According to the local weather forecast, irrigation is carried out before the cold current strikes, and the temperature near the ground and the foliage is increased to form a microclimate that can prevent or mitigate the hazard. Generally, the irrigation effect is best 1-3 days before the temperature is lowered, and the effect of selecting the breeze or the calm wind is significant.

4. Smoked smoke and frost. When frost occurs, the method of fumigation in the field has a good anti-frost effect.

Regardless of irrigation and antifreeze, or smoke and frost protection, priority should be given to key areas that are prone to frost damage and those that are susceptible to frost damage.

Remedial measures after freezing damage

Wheat has a strong adaptability. When the main stem and the big tiller are frozen and dead, the root system still absorbs nutrients and water. The latent buds of the base part are rapidly sprouting and growing. If they take timely remedial measures, they are likely to be sharp. Timely apply a small amount of quick-acting nitrogen fertilizer, apply 5-7.5 kg of urea per acre, combine irrigation, cultivating and loosening soil to ensure remediation.

⊙ vegetables

There are two kinds of cold and cold damage and cold spring frost in spring and cold: the cold damage mainly occurs in March-April, causing damage to spring vegetables, such as rotten roots, dead seedlings, falling flowers and fruit, and early convulsions; late spring frost generally occurs in the middle and late April, making the field The surface of growing vegetable plants is frosted and damaged. In the event of cold spring, the damage in the arch shed is heavy, followed by the greenhouse; the adult plants are more harmful than the seedlings, and the flowering results are the heaviest. Most leafy vegetables have stronger tolerance to low temperature and lighter damage, while melons and solanaceous vegetables have poorer cold tolerance, so they are more affected when they are cold. The effects of cold spring on different growth stages of vegetables and their countermeasures are summarized below.

Seedling stage

Most of the current arch shed vegetables are in the slow seedling stage or the germination stage. If this period encounters a cold current, the aboveground leaves are firstly victimized. The seedlings of the seedlings are chlorotic at the edge of the cotyledon, and the appearance of "white borders" appears. The normal temperature recovery will not affect the true hair growth. True leaf damage often manifests as dark green leaves and gradually dry up. The growth point is more serious, which often causes the top bud to be cold and does not produce new leaves. This will greatly prolong the slow seedling period. If the seriously damaged plants cannot recover after the weather turns warm, they must be supplemented separately. In particular, seedlings that are planted on the edge of the shed film often suffer from growth points.

Response measures: Vegetable farmers should promptly prevent cold springs, become passive and take the initiative to improve the stress resistance of seedlings in sunny weather, even if it occurs, it can significantly reduce the impact on vegetable seedlings. Suggest:

First of all, seedlings should be cultivated. Seedlings are strong and their ability to withstand adverse environments will be greatly enhanced. Cultivate strong seedlings, seedling management should pay attention to strengthen the light and control the temperature of the seedbed. In general, most vegetable seedling temperature should be controlled at 25 ° C ~ 30 ° C, night 18 ° C ~ 20 ° C. Pay attention to reducing the humidity, and the soil of the seedbed should not be too wet. Also need time and seedlings to prevent the formation of "high feet". In the seedling stage, there is generally no topdressing. In order to supplement the nutrition of the seedlings when the seedlings are used for seedlings, it is necessary to carry out the top dressing according to the seedlings. Generally, 0.2% potassium dihydrogen phosphate solution is sprayed. If the seedling leaves are light, the 0.2% urea solution can be sprayed together, and the seedling period can be sprayed 2 to 3 times.

Secondly, low temperature refining is carried out before planting. The purpose of the seedlings is to increase the adaptability and stress resistance of the seedlings to the cultivation environment. The method is to gradually reduce the temperature of the seedbed 7 to 10 days before planting, control at 18 °C ~ 20 °C during the day, control at 10 °C ~ 12 °C at night, and shorten the resistance of 8 °C ~ 10 °C for a short time to enhance the stress resistance of the seedlings, colonization After the easy to survive. Try to increase the amount of ventilation, pay attention to shading at noon, so that the seedlings are in a cool environment. Also pay attention to controlling the amount of water.

Adulthood injury

When the cold spring occurs, the greenhouse vegetables are exposed to low temperature hazards, and often the leaves are dry, the plants are wilting, and the young leaves are chlorotic and yellow. In severe cases, the growth point is dry, and the roots of the ground do not have new roots.

Response measures: Vegetables have strong plants, and their resistance is naturally high. They also suffer from cold springs, and their damage is much lighter. Therefore, robust plants should be cultivated. The following points should be done:

First, the seedlings of vegetable seedlings are very important after slow seedlings. Due to the high temperature of the shed in the current sunny weather, and the sufficient slow seedling water, it is easy to cause the seedlings to grow long, so it is necessary to carry out temperature control seedlings to promote the growth of the seedling roots. The focus is on controlling the night temperature. If the temperature in the shed is high during the day, the night temperature is controlled at around 14 °C. If the weather is not high during the rainy weather, the night temperature should be controlled at around 16 °C. In a few sunny weather, the night temperature can be controlled at around 12 °C to prevent the seedlings from growing.

Second, it is important to cultivate a strong root system. Robust root system is the basis for improving the resistance of vegetables. After slow seedlings, it is necessary to diligently promote the development of roots. After the watering of the seedlings is poured, it is necessary to carry out early tillage as much as possible. For the first time, shallow tillage is necessary to promote root extension. For the second time, proper deep cultivating is needed to promote the lowering of the root system.

The third is scientific fertilization, which promotes roots and strong trees. According to soil moisture combined with watering and fertilization. It can be used to promote the fruit and attack the fruit type 5 to 7.5 kg/mu, or to apply the special formula fertilizer of Bailingke. This can not only meet the needs of vegetable growth, but also enhance the effect of ground temperature on root growth.

Damaged during flowering

When the cold spring occurs, the vegetables in the flowering stage are affected by the low temperature, which affects the pollen activity of the flowering at this time, thus affecting pollination and fertilization, often leading to falling flowers and fruit. The low temperature during the flowering period often leads to poor flower bud differentiation, which causes the subsequent flower or fruit to become a deformed flower or a deformed fruit. If a heavy cold spring occurs, the melons may even have a flower topping.

Response measures: Due to the delicate flowering period of vegetables, most of them will fall into the fruit or deformed flowers and fruit when they are victimized. Therefore, taking precautionary measures as soon as possible is the key to maintaining the quality of flowers during the cold spring. Suggest:

First of all, pay attention to the weather forecast in time when the cold spring often occurs, so as to take preventive measures as soon as possible. And pay attention to the temperature before the weather, it is best not to water in the greenhouse, in order to prevent the spread of various diseases caused by low temperature and high humidity.

Secondly, it is necessary to increase the insulation measures when encountering the cold weather, which requires multi-film coverage. Therefore, the insulation film inside the shed should not be removed early. In recent days, the weather has improved significantly and the temperature has risen very quickly. As the temperature rises, many vegetable farmers have removed the insulation film (two membranes, three membranes, etc.) in the shed early. Remind the vegetable farmers that due to the cold springs in the late March to the beginning of April, the external temperature will often drop to around 0 °C, and the temperature inside the shed will also decrease. Suddenly, the temperature drop is too large, which often adversely affects the growth of vegetables in the shed. It is also necessary to cover the second film to increase the temperature inside the shed. Therefore, it is not possible to remove the insulation film in the shed. If the vegetable farmer is afraid that the temperature of the shed is too high, the insulation film in the shed can be placed on both sides of the shed, so that when the cold spring occurs and the temperature in the shed becomes low, the insulation film is fixed on the steel wire on the shed with a clip. It is much better to blindly remove early.