Typical symptoms and damages of drought: from sowing to emergence, surface soil moisture deficiency, seeds in dry soil, unable to germinate and emerge, delay in sowing and seedling period, easily causing seedlings to become seedlings; seedlings are weak due to drought seedlings , Small plants, stunted growth, population growth is not neat. The countermeasures are: increasing organic fertilizer in areas where drought frequently occurs, deepening soil remediation, fertilizing soil fertility, improving soil buffering capacity and drought resistance; adopting water storage and soil conservation cultivation techniques and establishing “soil reservoirsâ€; selecting drought-resistant varieties; mulching Cover cultivation; Drought-resistant sowing: such as robbing sow planting, sitting water (filtering water) sowing, dry seed wet, deep sowing shallow cover, no tillage sowing, pay attention to preparation before sowing, waiting for the rain to broadcast.
After the drought: 1. Classified management. Emergence of more than 70% of the plot, postponed Dingmiao, stay two plants, security groups; more than 50% of the land emergence of the seed, as soon as possible germination sit water replant; lack of seedlings in more than 60% of the land, to plant early corn or other crops. 2. Excavate water sources and increase effective irrigation area. 3. Do a good job of sowing preparations. When soil moisture is appropriate in case of rain, sow planting. 4. To strengthen field management, the land that has emerged should be cultivated as early as possible, cultivated in shallow areas, and reduce evaporation.
Symptoms and damages caused by windstorms include: 1. Lodging and breakage of seedlings; dusty weather causes seedlings to be covered with dust and leaves and damage to the leaves. 2. Soil compaction, high humidity, and insect pests affect the root development, resulting in small roots and shallow roots, and prone to root collapse. 3. When the seedlings and the jointing stage are covered by wind, the plants can generally recover upright. The countermeasures are: 1. Use resistant varieties; the soil is deep and loose and hardened. 2. In areas with heavy winds, pay attention to properly reduce planting density and plant corn in the wind direction. 3. The seedling stage lodging is often accompanied by more rain and damage, and the water is drained in time after the disaster. 4. Strengthen management, such as earthing, cultivating, and removing compaction, can also increase available nitrogen fertilizer to improve plant growth.
The typical symptoms of hail and damage: direct damage to corn plants, frostbite plants; soil surface is compacted, ground panel knots; stems and leaves infected after trauma. The degree of damage depends on the size and duration of the hail block. Improve artificial anti-smashing facilities such as earthen cannons, anti-aircraft artillery and rockets to prevent, eliminate and reduce disasters in time. As soon as possible after the disaster, assess the impact on production. The main measures: 1. The ability to recover after the seedling period is strong, as long as the growth point is not destroyed, it can restore growth, and carefully destroy the species. 2. Timely cultivating loose soil, breaking compaction, increasing ground temperature, increasing soil permeability, and applying topdressing available nitrogen fertilizer (urea 5-10 kg per mu); spraying new leaf potassium dihydrogen phosphate 2-3 times after the new leaf grows. Promote new leaf growth. 3. Pick out the broken leaves that are wound together so that the new leaves can grow smoothly. 4. Be alert to the occurrence of diseases.
The typical symptoms and damages of low-temperature chilling injury: After the corn seedlings were damaged by low temperature, the metabolic efficiency decreased, the cell membrane permeability decreased and the protein was degraded. The browning and wilting of the mesocotyl and coleoptile, the appearance of water-stained leaves and incomplete development of the leaves, and even the impaired growth of the seedlings do not survive, and the chilling injury symptoms can continue until the growth period is restored. Cold damage caused the growth retardation of plants and reduced the individual quality of the seedlings. The countermeasures are: 1. Do a good job of variety division and use cold-resistant varieties. 2. Seed treatment. With the concentration of 0.02% -0.05% copper sulfate, zinc chloride, ammonium molybdate solution soaking, can increase the germination of corn seed at low temperatures, reduce chilling injury. 3. Suitable sowing. According to the minimum temperature of germination of maize seeds, combined with local meteorological conditions, arrange appropriate sowing time, to avoid the threat of cold damage.
The typical symptoms of freezing injury and damage: When the temperature is lower than -1 °C, the freezing damage causes the aboveground leaves and tissues to be immersed, wilting to death. Since the growth point of the corn 6 leaf before the exhibition is underground, when the temperature rises, the growth point can often resume growth. When conditions are right, plants can grow new leaves 3-4 days after freezing. The essence of frost-infested plants is low-temperature freezing injury, but the damage to plants caused by freezing is not due to the direct effect of low temperature, but mainly due to the freezing or freezing of plants in plant tissues. The countermeasures are as follows: 1. Grasp the laws of occurrence of local low-temperature frost, select suitable varieties for the growth period, and sow the corn in the “warm head and cold tailâ€. 2. Choose crops or varieties with strong cold-resistance and adopt cultivation techniques that can improve the cold-resistance of crops. 3. After the occurrence of frost, it is necessary to investigate the victim’s situation in a timely manner and formulate countermeasures so as not to easily destroy the species. Carefully observe whether the growth cone of the main stem is frozen (deep water immersion). If only the upper leaves are damaged, the heart leaves and the growth point are not affected basically. The field management can be strengthened, and the cultivator loosens the soil and raises the ground temperature in time. Efficient fertilizer is applied to accelerate the growth of corn and promote the growth of new leaves. For fields where freezing injury is particularly severe and most of the corn is killed, timely assessments are required and early maturing corn or other crops can be planted.
Symptoms and damage caused by picklings: Maize is particularly afraid of picking in the bud and seedling stages. Sprouts sprouted at the 3rd leaf stage, inhibiting root growth and absorption activities, wilting, yellowing, slow growth, and even large areas of seedling death. Low-lying terrain, heavy soil, and frequent rainfall are prone to occur. The countermeasures are: frequent flooding in the seedling stage, paying attention to supporting irrigation and drainage ditches; selection of flood-resistance varieties; adjustment of sowing date, making the sensitive phase of the most fearful flooding as early as possible before the start of the rainy season; smoothing low-lying land; adopting proper cultivation such as ridge cultivation the way. After damage occurs, damages should be promptly assessed. Main measures: 1. Drain the mud on the leaves in a timely manner. 2. Shallow cultivator, planer, ventilation and scab. 3. Timely application of available nitrogen fertilizers, such as ammonium sulfate, ammonium bicarbonate, supplement soil nutrient loss, restore root growth, and promote weak to strong. 4. When more than 60% of dead seedlings are replanted or changed to other crops.
Symptoms and damages at high temperatures: young leaves at high temperature at the seedling stage start to dry out from the tip of the leaf, resulting in the death of half leaves or even the entire leaves; high temperatures damage the chloroplast structure of the leaves, weaken photosynthesis, increase respiration, increase consumption, and reduce dry matter accumulation. The plant growth is weak, the root physiological activity is reduced, and it is easily infected by pathogenic bacteria to cause seedling disease. The countermeasures are: 1. High-temperature areas, pay attention to breeding and promotion of heat-tolerant varieties; adjust the sowing date so that the flowering pollination season avoids high-temperature weather; appropriately reduce the density, wide and narrow line planting, and cultivate robust plants. 2. Sprinkle irrigation water in proper period to change the microclimate of farmland.
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