In recent days, there has been heavy rain throughout the province, including heavy rains along the Huaihe River and south of the Huaihe River. Due to the intense rain, corn in some areas was flooded. In order to reduce the impact of waterlogging on corn growth, field management measures are as follows.
1. Types of waterlogging
1. Waterlogging and waterlogging at the seedling stage. The waterlogging of corn bud refers to the period from the time when the maize absorbs water and germinates to the expansion of the third leaf of the maize seedling due to flooding or soil moisture that affects the germination, emergence and growth of maize seeds. Phenomenon: Waterlogging at the seedling stage of corn refers to waterlogging that occurs during the period from the third leaf of corn to the jointing of corn.
2. Mid-term waterlogging. Mid-term corn waterlogging refers to waterlogging from the jointing period to the grain formation period. After jointing, the ability of corn to tolerate waterlogging is significantly higher than that of the seedling stage, and with the advancement of the growth process and the formation of organs, the ability of waterlogging resistance is further enhanced.
3. Waterlogging during the filling period. Waterlogging during the filling period refers to the waterlogging that occurs during the corn filling period and its subsequent growth stages. After the corn enters the filling stage, although the suitable soil moisture has decreased compared with the previous growth stage, the organs have been fully formed and the aerial roots have also grown, and the ability to withstand waterlogging has not decreased but increased. Short-term flooding or stagnant water generally has no major impact on yield.
2. Corn waterlogging hazards
1. Waterlogging hazard at seedling stage. Obvious waterlogging will be formed when the soil water content of corn seedling reaches 90% of the maximum water holding capacity. During the one month period from planting to jointing of summer corn, the total precipitation exceeds 200mm, or the ten-day precipitation exceeds 100mm, waterlogging will occur. Corn seeds are most sensitive to waterlogging when they absorb water and expand and the main roots begin to elong. If bud flooding occurs for 2 to 4 days, reseeding is required.
2. Mid-term waterlogging hazard, after the jointing of corn, the waterlogging tolerance is obviously enhanced. Before and after maize tasseling, the appropriate soil moisture is 70% to 90% of the maximum water holding capacity of the soil, and the normal growth and development of maize will be affected when the soil moisture is greater than 90%. If the ten-day precipitation exceeds 100mm or the total precipitation from late July to mid-August exceeds 200mm, waterlogging will occur. The accumulation of water in the jointing period is more than 5 days, and the water accumulation in the tasseling period is more than 7 days.
3. Waterlogging hazard during the filling period. The corn filling period requires suitable soil humidity. With the progress of the filling process, the maximum water holding capacity of the soil will gradually drop from 80% to below 60%, which can be obvious after waterlogging. Promote the occurrence of aerial roots. Maize has strong waterlogging tolerance and generally does not cause significant yield reduction.
3. Exclude bright water and reduce stains
Clean up the three ditches in time, make sure that the surrounding ditches, waist ditches and border ditches are matched, remove the silt in the ditches, ensure that the three ditches are unblocked, improve drainage efficiency, and drain open water in the field. As the soil is saturated with water, it is necessary to drain the field water while draining the field water to prevent "dumb waterlogging".
4. Classified management according to seedling situation
1. Corn before and after jointing
Due to the loss of some nutrients due to flooding, after removing the stagnant water, promptly apply quick-acting nitrogen fertilizer to promote the recovery of corn growth, and apply about 10 kg of urea per mu. It can also be sprayed with growth promoters such as fulvic acid to enhance the vigor of the corn root system, improve the resistance to stress, and promote the growth of corn. To strengthen disease control, spray with 70% thiophanate-methyl 800 times solution or 50% carbendazim 500 times solution, and spray again every 7 days. If corn lodging occurs before and after jointing, it generally does not need to be raised manually.
2. Corn before and after tasseling and pollination
After draining the stagnant water, apply quick-acting nitrogen fertilizer in time to promote the recovery of corn growth, and apply about 10 kg of urea per mu. For example, corn lodging occurs before and after tasseling and pollination. After falling, the plants overlap each other, and natural recovery is difficult. It will not only affect the progress of photosynthesis, but also affect the normal growth and development, silking and pollination, requiring artificial support. Generally, rush up within 1 to 2 days after the occurrence of lodging. Once the plant is bent and grows upwards, it can no longer be supported.
3. Corn after filling
The spring corn is in the filling stage at this time, and topdressing 5 kg to 10 kg of urea per mu, strive for large grains. During this period of corn lodging, about 10 plants can be bundled together to prevent the ears from moldy and pests; the mature spring corn is actively harvested and dried to ensure that the particles are returned to the warehouse.
5. Replanting fresh corn
For water-destroyed fields, all parts of our province can be replaced with fresh corn before the end of July, and early-maturing varieties are preferred. The planting density of fresh corn is 3000 plants/mu. In order to promote the growth of corn, it is recommended that all base fertilizer be applied. Under the current medium fertility level of the soil, the total nitrogen per mu is 15kg, and the ratio of nitrogen, phosphorus and potassium is 3:1:1. Compound fertilizer (15:15:15) is about 35kg and urea is about 20kg per mu.
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