Countermeasures for Low-Temperature Freezing Damage in Rice Seedlings

During the period of rice breeding in spring when the temperature fluctuations are relatively large, the high and low temperature, especially the low temperature, has a great influence on rice seedlings. From April 7 to 9, rare temperatures of minus 7°C appeared in our province, and there will be sudden cold weather in the future. In this regard, some suggestions for countermeasures are proposed for reference by the technical department and the vast majority of rice farmers.

Sowing time

The daily average temperature can be sown by 5°C, but it is not as soon as possible. The sowing time should be determined according to the planned date of transplanting. The 3.5 seedling seedlings of the flat disc insertion seedlings are 30 days ahead of schedule and the seedling seedlings of the seedling seedlings are planted 35 days ahead of schedule. This includes the time for seedlings 5 ​​days before transplanting. For example, the program will be transplanted on May 15. The transplanter for the flat machine should be planted on April 15th and the seedlings should be planted on April 10. The seeding volume of the flat-disk mechanical transplanting seedlings is large, and the best transplanting day for each seed sown is within 5 days. If it is extended, it will become old seedlings, and the time for replanting the seedlings will cause a decrease in production. Therefore, large households or cooperatives that have been transplanting rice for a long period of time must be planted in stages in accordance with the criteria for inserting a batch after every 5 days. The late-maturing varieties planted in the plain areas of our province are basically safe and mature as long as they are sown before April 25th.

Soaking

Rice seed soaking depends on the conditions of the farmer and the days of soaking vary greatly. To germinate rice seeds must have two conditions, that is, the amount of water absorption reaches 25% of its own weight, and the accumulated temperature of water after soaking seeds reaches 100°C. If soaking the water temperature 10 °C should be soaked for 10 days, 20 °C soaked for 5 days.

At present, the seeds have been immersed, but due to the effects of the cold, the seeds should not be soaked, otherwise phytotoxicity will occur. Should promptly bring out the soaked seeds to germinate, keep it in a cold place that is not frozen and can not continue to grow buds. When the seeds are dry at the time of sowing, they can be soaked again with warm water for 5 hours. The seed thus kept is sown within 10 days, and the budding rate has little effect.

Germination sowing

After soaking, direct sowing is more likely to occur after 4 days than the normal season of germinating seeds. If encountering low temperatures, the seedlings will emerge 7-10 days later. When transplanting, the leaf age will be 1 leaf less, the seedlings will be missing, and the emergence will be 10% lower. Therefore, germination must be done at any time, and mechanical transplanting should be the case.

The standard of budding is that rice buds are exposed to 1 mm. The germination rate reached more than 80% in a timely manner to get a cool place, spread about 10 cm to cool down, in the cooling process can also be about 15%.

Seeding good seed treatment

At present, many farmers have planted seedlings that have already been planted, but they have not yet been placed in seedbeds and should be treated as appropriate. If the seed sown is in the house, it can be guaranteed that when the temperature is above zero, it can be placed in the shed at a low temperature inside the house. If the place where the temperature is placed is similar to the temperature in the shed, it can be placed directly in the shed.

Seedling plate treatment

Seeds that have entered the shed, when the weather forecast reaches the sub-zero temperature, the seedbed should be irrigated one day in advance. In this way, while using the daytime temperature to raise the bed temperature, it is possible to reduce the freezing damage rate of seeds by relying on the slow heat release characteristics of water. Rice seeds can tolerate temperatures below -5°C during the shoot, so the water can be maintained at a certain temperature to survive the current low temperature effects.

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