A drought affects yield
The effects of drought on maize yield are as follows:
Make the growth period abnormal. Drought occurs in the corn seedling stage, which inhibits the growth rate of corn and delays the development period significantly. It occurs in the jointing stage, which promotes the early maturity of the corn and leads to a significant shortening of the developmental stage.
Inhibit plant height. The corn that suffered from drought grew significantly short.
Dry the leaves. The drought will cause the corn leaves to shrink and the area of ​​green leaves for photosynthesis will decrease.
Change the ear traits. The drought will shorten the ear length of the corn ear, and the number of fruit pieces will decrease, eventually leading to a reduction in yield.
The main characteristics of maize in the dry field are as follows: drought in the seedling stage, slow growth of the plants, yellowing of the leaves, and small stalks. Even if the rain is reconciled, the thick stalks cannot be formed, which affects the breeding of the big ears. The corn trumpet period is dry, the ear development is slow, and the half-ear and the upper part of the ear are degraded. In severe cases, the development of the ear is blocked and aborted, forming an empty ear plant. In the early stage of tasseling, the stamens were delayed, resulting in poor pollination and the formation of flower seeds. If you encounter dry and hot weather during the pollination period, especially the high temperature weather above 35 °C, the pollen vitality will decrease, affecting pollination, forming a thin rod or an empty rod. The appearance of the filaments constantly stretches out the leaves to form a long beard. Corn that has been in arid or semi-arid state has short stature, slow growth or stop growing, wrinkled leaves, yellowing, and even death. If the drought is relieved, the plants will resume growth and will be in love with each other. A number of small ineffective ears are formed in the upper and lower nodes of the ear, and the corn borer is easily attracted to the stems and tender ears. When the corn in the filling stage is suffering from drought, the grain is not full, the ear stick is soft, and some of the grains on the cob are arranged from large to small ladder.
B How to deal with drought
It is necessary to give full play to the role of the existing emergency drought-resistant water source project, watering and seedlings. Concentrated water sources are given priority to ensure high-yield land and water in critical conditions, with key grain-protected grain fields and high-efficiency fields. It is recommended to use the "ground dragon" for sprinkler irrigation. After watering for 1 to 2 days, it is necessary to remove the soil and eliminate the soil compaction to prevent water evaporation.
If there is no hydration condition, it is necessary to respond to the following aspects:
Variety selection. Pay attention to the selection of corn varieties with strong seed arching ability, grain filling and dehydration, and drought resistance. In the middle and lower fertility and saline-alkali plots, planting thin or semi-resistant medium-premature and early-maturing drought-tolerant varieties; in areas with high fertility, high levels of organic fertilizers and fertilizers, and irrigation conditions, choose to plant dense and semi-resistant Medium-milk or mid-late ripe high-yield varieties.
Seed treatment. Pick uniform seeds and choose to dry for 3 days on sunny days to improve germination, disease resistance and uniformity. The corn seed is coated with a drought-resistant composite seed coating agent to prevent pests and diseases at the seedling stage, and to enhance the vitality of the root system and self-resistance. The germination seeds cannot be coated to prevent phytotoxicity.
Scientific fertilization. Increase the application of potassium fertilizer, increase the utilization of water by reducing plant transpiration, and enhance the drought resistance of the crop itself. It can be combined with planting 100-150 kg of potassium chloride per hectare. The younger plots should use the urea or potassium dihydrogen phosphate aqueous solution for foliar spraying in the morning or evening, increase the leaf moisture of the plants, cool down and humidify, and provide the necessary water and nutrients to the leaves to promote corn growth.
C waterlogging affects production
At the seedling stage, the emergence of corn to the seven leaves is susceptible to damage. When the field water holding capacity is above 90% for 3 days, the corn is red, thin and thin, and the growth stops. If the continuous rainfall is more than 5 days, it will cause weak yellow or death.
In the middle and late period, it is a period of strong sorghum tolerance. The depth of the ground flooding is 10 cm for 3 days. Although the leaves are not exposed to the water surface, the yield will be greatly affected. Before the 8-leaf stage, the growth point was not exposed to the ground. At this time, the yield reduction was the most serious, and even the harvest. If there is continuous rainy weather for more than 10 days, the photosynthesis of maize is weakened, and the plants are often thin and empty.
After the big bell period, the tolerance of corn is gradually increasing. The sum of rainfall between the end of July and mid-August is greater than 200 mm or the rainfall in the first half of August is greater than 100 mm, which will affect the normal flowering pollination of corn, resulting in a large number of bald and empty particles.
D How to deal with disasters
Quickly drain and drop the stains. The farmland has accumulated water for a long time, the soil is seriously deprived of oxygen, and the root function of the crop is degraded or suffocated. Therefore, the accumulated water in the field and the stagnant water in the ploughing layer should be discharged as soon as possible after the rainstorm. At the same time, the paste on the leaves and stems should be removed or washed to restore the normal photosynthesis of the leaves.
Early help to fall down the plant. After the storm, the fallen corn leaves and leaves overlap, which is not conducive to ventilation and light transmission, causing the field to close, which will cause the spread of pests and diseases and reduce production. Therefore, it is necessary to raise the fallen corn as soon as possible. If the lodging occurs before the jointing, the corn itself has a certain ability to restore its erect, and it is not necessary to straighten it manually. If the lodging occurs after the tasseling, it must be artificially lifted as soon as possible, preferably within 2 to 3 days.
Spray foliar fertilizer in time. After the water in the field is discharged, use 45-60 kg of 0.2%-0.3% potassium dihydrogen phosphate + 1% urea aqueous solution per acre to spray the leaves, spray once every 7 to 10 days, and spray 2 to 3 times to meet The demand for nutrients in corn before the root absorption function has not recovered.
Apply fertilizer to promote growth. After the root function of the plant is restored, root fertilization is carried out to supplement the soil nutrients and promote plant growth. The corn is in the plot before the heading and flowering period, and 20 to 25 kilograms of high-concentration compound fertilizer is applied per acre, and 7.5 to 10 kilograms of urea is applied per acre in the big bell mouth period or the heading and flowering stage.
Grasp the cultivating soil. Grab the weather after the rain, and plow the soil 1 to 2 times in time to loosen the soil and roots, remove the knot and prevent the roots.
Control pests and diseases. For the affected plots, focus on the prevention and control of corn mites and corn plaques in the middle and late stages.
According to the disaster situation classification and correction. The disaster is not very serious, and it can improve the soil conditions by taking effective measures to promote the recovery of corn after the disaster. The disaster is very serious, the land is not harvested, the plant is destroyed in time, and other crops with short growth period are replanted. Before August 10, you can switch to Chinese cabbage, radish, and mustard greens. After August 10, you can grow early-maturing or cold-tolerant vegetables such as coriander, spinach, cherry radish, or scallions. It is not appropriate to destroy other crops in the late stage of the disaster relief. The plots with good irrigated conditions can be considered for the construction and production of facility agriculture. (Lv Guiyun)
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Adjust the sowing date to prevent corn shrinkage
Maize rough disease is a viral disease that is prevalent in recent years in our province. It is devastating and difficult to cure once it occurs.
The rough disease is transmitted by the gray planthopper in a persistent manner, and the corn can be infected during the whole growth period. The typical symptoms after onset are dwarfing the plants, the leaves are dark green, and the leaves are opposite, such as spring bamboo shoots, and severe heading. The diseased plants in the late growth stage also showed normal length between the internodes of the females, shortened between the internodes of the ears, shorter than the ears of the female ears, and the ears were deformed, and the bald tip, the leaves of the leaves and the leaves of the leaves had obvious uplifts. White strips. In the field, some plants are generally infected, and the diseased plants near the ground and the weeds near the road are concentrated.
The maize seedling stage to the 7-leaf stage is sensitive to the disease of maize rough disease, and various grass crops and weeds are the host plants of maize rough disease. Spring corn sown in mid-April in early spring and summer corn sown in mid-June are mild. From mid-May to early June, the first generation of adult larvae was poisoned. At this time, the wheat was yellow and the young plants in the field were few, causing the gray locusts to concentrate on spring corn and interplanting corn.
Therefore, the focus of prevention and control of corn rough disease is to adjust the sowing date, sowing in a timely manner, summer maize does not advocate interplanting, should be affixed to sowing, generally not planted before June 5. Before sowing, the seeds are coated or seeded with a seed coating agent containing a systemic insecticide such as carbofuran to effectively control the seedling stage. In the seedling stage, in the vicinity of the field or in the free land, such as the land, combined with corn chemical weeding for disease prevention and pest control. It can be used with 4.5% beta-cypermethrin 2000 times solution and 1.5% phytopathic acid No. 2 800 times solution, and used twice a day for 7 days. In the early stage of the disease, 20% virus A500 times solution or 1.5% phytophthora 2 800-1000 times solution, add bryostatin 6000 times solution +0.3% potassium dihydrogen phosphate mixed spray, 7 times a day, for 3 times. At the same time, the application of organic fertilizer and phosphorus and potassium fertilizer will promote the healthy growth of jade, shorten the period of illness and reduce the chance of drug transmission. Diseased plants found in the field should be removed in time, concentrated or buried, to reduce the source of infection.
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