Winter corn is a winter cultivated crop that is suitable for the development of South Asian tropical and tropical low-heat valleys. It is characterized by high yields, and can be used to harvest dry grains as high-quality fine feed and sell green food. After harvest, its stems and leaves are fresh and green. Rich in nutrition, it is an important source of green feed for large livestock at the turn of spring and summer, with significant economic and social benefits. In recent years, it has developed rapidly. In some areas, planting winter corn has become a new bright spot for farmers to increase their incomes. Since corn is a warm crop, winter planting in areas with long frost periods is vulnerable to frost. Adopting the following scientific antifreeze measures is of great significance to improving the yield and benefits of winter corn.
First, the corn growth and development requirements of temperature Corn seeds germinate at 6 ~ 7 °C, but the germination is very slow, easy to infect bacteria and mold rotten phenomenon. The optimum temperature for germination is 25 to 30°C. When the soil temperature is stable at 10 to 12°C in a 5 to 10 cm soil layer, the soil can be normally excavated. If corn encounters low temperature and frost during its growth and development, it will suffer frost damage and reduce its production. However, as long as the management of cultivating, top dressing, weeding, and pest control is strengthened, some losses can still be recovered. Ground temperature of 20-24°C is most suitable for root growth, and below 4°C root growth will stop. Tasseling and flowering period is a period of high temperature requirement for corn, and the daily average temperature is 25°C. During flowering and pollination, if the temperature is higher than 35°C and the weather is dry and the soil moisture is insufficient, the pollen is liable to lose its vigor, and the filaments are easy to wither, often resulting in the phenomenon of "baldness" and "rare grains." During the grouting period, if the temperature is less than 17°C, it will affect the transport and accumulation of starch, resulting in severe reduction in production.
Second, the main performance of winter corn frost damage Winter corn frost damage occurs between 17.6 ~ 20.4 °C, that is, when the daily temperature difference is greater than 17 °C, began to appear frost symptoms, the larger the difference between daily, corn freeze damage The more serious. The number of effective leaves after freezing injury of maize was reduced, the plants dwarfed, the ear was smaller, the seeds were thin, the grain weight was reduced, and the yield decreased. Mild frost damage, reduced production by 10% to 20%; moderate frost damage, reduced production by 30% to 40%; severe frost damage, reduced production by 60% to 70%; especially serious, there is no income.
Third, the winter corn frost disaster prevention measures
1. Reasonable layout. The low-heat valleys and dam areas with an average annual temperature of 18°C ​​or more can develop winter corn production; regions with an average annual temperature of less than 18°C ​​should not develop winter maize; regions with an average annual temperature of 18 to 19.5°C have annual winter maize crops. Different degrees of frost damage occur, and in the sub-suitable areas where winter corn is laid out, frost prediction and prevention must be strengthened. Areas with an average annual temperature of more than 19.5°C are basically frost-free in winter and are suitable areas for the development of winter maize. Pouring conditions and soil conditions are the most restrictive factors for the production of winter corn, and the key is to pay attention to the construction of water pouring facilities and other health care cultivation techniques.
2. Scientific selection. Corn is a cultivable dry land crop with a large amount of water. In the winter, it is necessary to choose a sandy loam soil field with good irrigation and drainage conditions.
3. timely sowing. In frost-covered areas, the best sowing dates are: open field cultivation on November 15 to 25; mulching cultivation from November 25 to December 15. In frost-free areas, they may be adjusted for market demand and may be broadcast in early or late. Whether or not there is frost, it must be done: the sowing date of early sowing is based on the stability of the daily average temperature of the winter corn during the flowering period of over 18.5°C; the sowing date of the sowing shall not affect the subsequent sowing and planting.
4. Irrigation anti-frost. After mid-January, irrigation and anti-frost began, and irrigation was performed 5 to 7 days until the end of the frost period. Through irrigation, increase the temperature and humidity to achieve the purpose of frost protection. In order to improve the anti-frost effect of ice-filling, the irrigation and drainage can be done freely. When the site is set, it is required to open the four-side ditch and the cross ditch so as to achieve smooth formation of the soil. When planting, it is required to sow at low ridges (that is, after planting cover soil, sowing and planting). This method is suitable for early and mid-term use of winter maize seedlings. The plant height is high at the post-emergence stage, and the frost protection effect on the middle and upper leaves is reduced.
5. Water spray anti-frost. The principle of water spray and frost protection: The temperature of the water in the ditch, river or pond is slightly higher than the temperature of the frozen corn leaves. When the ice leaves are sprayed with cold water, the temperature of the leaves rises slightly, and the degree of damage to leaf cells and tissue structure is significantly reduced. It can even lift the frost damage. Method of operation: After entering the frost period, stick to the field in the early morning of the morning and check the corn leaves for ice by hand. If icing occurs, use a sprayer to spray water on the leaves before the morning sun comes out (not warm water). This method is suitable for winter corn frost protection at different seedling ages.
6. Agricultural film cover top frost protection. With 60-90 cm wide plastic film or agricultural film, cut into 3 meters to 4 meters long, both ends of the 150-200 cm long arches tightly wrapped, two people operate, one end, will be tightly wrapped cover film seeded The direction of the line is over the corn seedlings (cover only the top, both sides are empty). The height of the cover film is preferably such that the corn leaves do not come into contact with the cover film (leaf blades are separated from the cover film by 10 cm). Both ends of the arch were cut into tip-shaped piles, and 10 to 15 centimeters were buried. After the frost period is over, cover the film for the next year. This method is suitable for winter corn frost protection at different seedling ages, and the height of the arch shelter can be adjusted according to the height of the corn in different growth periods.
7. Improve the frost-protection micro-environment by increasing the temperature of the plastic film. The winter corn planted with mulching film was used. After the membrane was released, the membrane opening was temporarily covered with clay. In this way, the heat absorbed by the soil, moisture, and air under the membrane during the day is released from the membrane opening at night and early in the morning, so that the air around the maize seedlings maintains a high temperature, which can reduce frost damage. After the frost period is over, cover the membrane with fine soil to facilitate warming, water conservation, and fertilizer maintenance. This method is suitable for early frost protection of winter corn seedlings.
8. Select high yield and middle-maturing hybrid corn varieties, increase the quality of farmyard manure, rational allocation of chemical fertilizers, timely pest control, weeding, cultivating strong seedlings, enhance the resistance of corn seedlings, and help prevent freezing injury.
Even if all the leaves below the ear of corn were frozen to death after corn frost damage, there are only 4 to 5 leaves of corn seedlings above the ear position. As long as the cultivator, weeding and top-dressing are strengthened, there will still be 20% to 30% of the yield.
First, the corn growth and development requirements of temperature Corn seeds germinate at 6 ~ 7 °C, but the germination is very slow, easy to infect bacteria and mold rotten phenomenon. The optimum temperature for germination is 25 to 30°C. When the soil temperature is stable at 10 to 12°C in a 5 to 10 cm soil layer, the soil can be normally excavated. If corn encounters low temperature and frost during its growth and development, it will suffer frost damage and reduce its production. However, as long as the management of cultivating, top dressing, weeding, and pest control is strengthened, some losses can still be recovered. Ground temperature of 20-24°C is most suitable for root growth, and below 4°C root growth will stop. Tasseling and flowering period is a period of high temperature requirement for corn, and the daily average temperature is 25°C. During flowering and pollination, if the temperature is higher than 35°C and the weather is dry and the soil moisture is insufficient, the pollen is liable to lose its vigor, and the filaments are easy to wither, often resulting in the phenomenon of "baldness" and "rare grains." During the grouting period, if the temperature is less than 17°C, it will affect the transport and accumulation of starch, resulting in severe reduction in production.
Second, the main performance of winter corn frost damage Winter corn frost damage occurs between 17.6 ~ 20.4 °C, that is, when the daily temperature difference is greater than 17 °C, began to appear frost symptoms, the larger the difference between daily, corn freeze damage The more serious. The number of effective leaves after freezing injury of maize was reduced, the plants dwarfed, the ear was smaller, the seeds were thin, the grain weight was reduced, and the yield decreased. Mild frost damage, reduced production by 10% to 20%; moderate frost damage, reduced production by 30% to 40%; severe frost damage, reduced production by 60% to 70%; especially serious, there is no income.
Third, the winter corn frost disaster prevention measures
1. Reasonable layout. The low-heat valleys and dam areas with an average annual temperature of 18°C ​​or more can develop winter corn production; regions with an average annual temperature of less than 18°C ​​should not develop winter maize; regions with an average annual temperature of 18 to 19.5°C have annual winter maize crops. Different degrees of frost damage occur, and in the sub-suitable areas where winter corn is laid out, frost prediction and prevention must be strengthened. Areas with an average annual temperature of more than 19.5°C are basically frost-free in winter and are suitable areas for the development of winter maize. Pouring conditions and soil conditions are the most restrictive factors for the production of winter corn, and the key is to pay attention to the construction of water pouring facilities and other health care cultivation techniques.
2. Scientific selection. Corn is a cultivable dry land crop with a large amount of water. In the winter, it is necessary to choose a sandy loam soil field with good irrigation and drainage conditions.
3. timely sowing. In frost-covered areas, the best sowing dates are: open field cultivation on November 15 to 25; mulching cultivation from November 25 to December 15. In frost-free areas, they may be adjusted for market demand and may be broadcast in early or late. Whether or not there is frost, it must be done: the sowing date of early sowing is based on the stability of the daily average temperature of the winter corn during the flowering period of over 18.5°C; the sowing date of the sowing shall not affect the subsequent sowing and planting.
4. Irrigation anti-frost. After mid-January, irrigation and anti-frost began, and irrigation was performed 5 to 7 days until the end of the frost period. Through irrigation, increase the temperature and humidity to achieve the purpose of frost protection. In order to improve the anti-frost effect of ice-filling, the irrigation and drainage can be done freely. When the site is set, it is required to open the four-side ditch and the cross ditch so as to achieve smooth formation of the soil. When planting, it is required to sow at low ridges (that is, after planting cover soil, sowing and planting). This method is suitable for early and mid-term use of winter maize seedlings. The plant height is high at the post-emergence stage, and the frost protection effect on the middle and upper leaves is reduced.
5. Water spray anti-frost. The principle of water spray and frost protection: The temperature of the water in the ditch, river or pond is slightly higher than the temperature of the frozen corn leaves. When the ice leaves are sprayed with cold water, the temperature of the leaves rises slightly, and the degree of damage to leaf cells and tissue structure is significantly reduced. It can even lift the frost damage. Method of operation: After entering the frost period, stick to the field in the early morning of the morning and check the corn leaves for ice by hand. If icing occurs, use a sprayer to spray water on the leaves before the morning sun comes out (not warm water). This method is suitable for winter corn frost protection at different seedling ages.
6. Agricultural film cover top frost protection. With 60-90 cm wide plastic film or agricultural film, cut into 3 meters to 4 meters long, both ends of the 150-200 cm long arches tightly wrapped, two people operate, one end, will be tightly wrapped cover film seeded The direction of the line is over the corn seedlings (cover only the top, both sides are empty). The height of the cover film is preferably such that the corn leaves do not come into contact with the cover film (leaf blades are separated from the cover film by 10 cm). Both ends of the arch were cut into tip-shaped piles, and 10 to 15 centimeters were buried. After the frost period is over, cover the film for the next year. This method is suitable for winter corn frost protection at different seedling ages, and the height of the arch shelter can be adjusted according to the height of the corn in different growth periods.
7. Improve the frost-protection micro-environment by increasing the temperature of the plastic film. The winter corn planted with mulching film was used. After the membrane was released, the membrane opening was temporarily covered with clay. In this way, the heat absorbed by the soil, moisture, and air under the membrane during the day is released from the membrane opening at night and early in the morning, so that the air around the maize seedlings maintains a high temperature, which can reduce frost damage. After the frost period is over, cover the membrane with fine soil to facilitate warming, water conservation, and fertilizer maintenance. This method is suitable for early frost protection of winter corn seedlings.
8. Select high yield and middle-maturing hybrid corn varieties, increase the quality of farmyard manure, rational allocation of chemical fertilizers, timely pest control, weeding, cultivating strong seedlings, enhance the resistance of corn seedlings, and help prevent freezing injury.
Even if all the leaves below the ear of corn were frozen to death after corn frost damage, there are only 4 to 5 leaves of corn seedlings above the ear position. As long as the cultivator, weeding and top-dressing are strengthened, there will still be 20% to 30% of the yield.
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