Is cold dew wind a cold injury?

Cold dew wind belongs to a kind of low temperature chilling injury.

Cold dew wind is a kind of weather that appears in southern China around the solar terms. It is the low-temperature chilling injury that will obviously reduce the temperature and reduce rice production after the invasion of cold air in autumn. Often occurs in the "cold dew" solar terms, hence the name "cold dew wind" (also known as "social wind").

Cold dew wind is one of the main meteorological disasters in the growth period of late rice in South China. Every autumn around the "cold dew" solar term is the key period for heading and flowering of late rice in South China. At this time, if it is damaged by low temperature, it will cause empty shells and shriveled grains, resulting in reduced production.

Cold dew wind can be divided into wet cold and dry cold. Wet-cold type is mainly due to the cold air from the north to the south meeting with the warm and humid air gradually weakening and retreating in the south, which usually leads to low temperature and rainy weather; It is characterized by low temperature, rainy weather and little sunshine. The dry and cold type is mainly strong cold air heading south, with northerly winds of 3-5, dry air, clear weather and obvious cooling; It is characterized by low temperature, dryness, strong wind and large temperature difference between day and night.

Characteristics and influence of cold dew wind

Cold dew wind is the main agrometeorological disaster in the late growth stage of late rice in double cropping rice areas in southern China. Every year from September to June in Gregorian calendar 10, most parts of China are in the transitional period between wind direction and winter wind in Xia Feng, and sometimes cold air suddenly goes south, and the temperature drops obviously, which makes late rice in heading, heading, flowering and filling suffer from low temperature hazards, seriously affecting the normal process of rice flowering, pollination and filling, resulting in empty shells and shriveled grains, leading to serious yield reduction.

Before and after the cold dew solar term (65438+1early October), it was the heading and flowering period of late rice in South China. If the daily average temperature is lower than 22℃ for three or more consecutive days, it will lead to empty shells and shriveled grains of late rice, which will lead to reduced production. Because cooling is usually accompanied by northerly winds. The cold dew wind weather in the middle and lower reaches of the Yangtze River generally appears in the middle and late September, while in South China it mostly appears in June 5438+ 10. Under normal circumstances, the empty shell rate of double-cropping late rice can reach 20%-30%, and it can reach 40%-70% in severe years, or even no harvest.

Low temperature affects the normal process of rice flowering, pollination, fertilization and filling, resulting in an increase in the percentage of rice grains and a light upturned ear, commonly known as "upturned ear head". The meteorological indexes of the harm of cold dew wind to rice vary with rice varieties and development stages.

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