Key points of cultivation and management of rice during cold wave in spring

I. characteristics of cold wave disasters

Due to the invasion of cold air, the temperature drops sharply by more than 10 ℃ in 24 hours, and the lowest temperature in this day is less than 5 ℃, which is called cold wave. In the middle and lower reaches of the Yangtze River, strong cold air moves south, causing the temperature to drop by more than 10 ℃ within 48 hours, also known as cold wave. The cold wave generally occurs in spring and autumn, especially in spring, and most of the cold wave in spring occurs from March to May. The cold wave mainly caused rotten seeds, rotten seedlings and dead seedlings in rice seedling stage.

II. Rice cultivation and management measures

1. The safe sowing time of early rice in Hunan is from late March to early April, which is the frequent stage of cold wave. According to the temperature requirement of rice growth and development, it is safe for early rice to sow when the daily average temperature steadily passes through 12 ℃ ~ 14 ℃. The safe sowing time of early rice in Hunan Province is from the Spring Equinox to Qingming. During this period, the seeds are sown in stages and in batches. The initial sowing time in southern Hunan is earlier than that in western and northern Hunan, and that in the plain is earlier than that in the mountainous area. During the spring sowing period, we should pay attention to listen to the local weather forecast, soak the seeds on the eve of the cold wave, accelerate germination during the cold wave, and sow seeds after the cold wave, and strive to sow seeds on a sunny day from 3 to 5 days after sowing.

two。 Select good varieties with high yield, strong cold resistance, suitable growth period, good rice quality and wide adaptability. At present, the local early rice varieties (combinations) with strong cold resistance are Changzaoxian 10, 99 Zaoxian 12, Chuangfeng 1, Xiang Group 1, 99 Zao 677, etc., and the hybrid rice combinations are Zhuliangyou 819, Luliangyou 996 and so on.

3. Reasonable cultivation mode ① chooses the appropriate way of raising seedlings. Our province mainly adopts plastic film mulching seedling raising and plastic film mulching soft disk seedling raising, and carries out seedling refining, 4-leaf water pipe and 4-leaf dry pipe to facilitate the cultivation of strong seedling. It is also used to raise seedlings with cold tolerance in dry land, and its sowing time can be about 7 days earlier than that of raising seedlings with water, the phenomenon of rotten seedlings will not occur, and the seedlings will emerge neatly. ② chooses nursery bed reasonably. Choose the plot with leeward to the sun, convenient drainage and irrigation and fertile soil as the seedbed. It can not only meet the needs of temperature, fertilizer and water for raising seedlings, but also take double measures of covering film and irrigation to protect seedlings when the strong cold wave comes. Scientific management of ③. During the cold wave, the nursery bed should be covered with strict plastic film, heat preservation and anti-freezing to prevent ventilation and leakage. If there are conditions, we should immediately irrigate and protect seedlings. After the cold wave, wait for the weather to improve, first release water, ventilate seedlings, and then remove the film. For seedlings with withered or yellow leaves but undamaged roots and stems: one is to raise seedlings in shallow water and use irrigation or watering to replenish water to keep the bed soil moist and promote the seedling to recover as soon as possible; the other is to promote seedling growth by applying fertilizer to promote seedling growth by topdressing 1000 kg of plant ash per hectare or spraying 0.2% potassium dihydrogen phosphate solution to promote seedling growth. The third is to prevent disease and protect seedlings, for the seedlings with bacterial wilt, spray seedlings with 55% dimethazone 1000 times liquid to improve the quality of seedlings; fourth, delay strong seedlings.