What are the natural disasters of rice?
Drought: In the northern rice-growing areas of China, the temperature rises rapidly in spring, the rain is insufficient in spring, and the spring drought is serious; Yunnan, Guizhou, Sichuan and other mountainous areas and plateau areas, as well as Hubei and Xiangxi mountainous areas, basically rely on natural precipitation or pond irrigation to grow rice. Due to the complex terrain, poor irrigation conditions, large runoff and continuous no rain, a spring drought occurred; The widespread winter rice fields in Sichuan province are proof of people's resistance to spring drought. The reason for the spring drought in Guangdong, Guangxi and Hainan is that under a single air mass system, a large amount of precipitation cannot be formed, exposing the drought; The middle and lower reaches of the Yangtze River and Fujian, Jiangxi, Hubei and other areas are controlled by the Pacific subtropical air mass in summer, resulting in stable high temperature weather, large evaporation and small precipitation, which are easy to cause serious water shortage and severe summer drought, often accompanied by strong heat damage, posing a serious threat to high-yield rice crops in this area. If autumn drought continues, the loss will be even greater. China's vast northwest region, located in the hinterland of the mainland, is weakly affected by the summer monsoon, and the summer drought and autumn drought are mostly serious.
Waterlogging: Rain waterlogging mostly occurs in rainy season, and heavy rains in summer and autumn often cause serious losses to rice production. Excessive concentration of rainfall caused floods. Rainstorms often occur in 7? August; In the south, it mostly happens in 6? August; The Sichuan Basin occurred in September; Huayou area is even in 9? June is still a concentrated rainstorm,165438+1October.
The seasonal distribution of heavy rain shows that the whole growth period of mid-season rice and the early stage of double-season late rice in southern China are most threatened by floods. Waterlogging is formed due to the influence of topography, which mostly occurs in low-lying areas, such as polder areas, river valleys, flat dams and other areas, and the occurrence of waterlogging aggravates the harm of rain waterlogging. For example, in August of 198 1, a serious flood disaster occurred in Sichuan rice-growing area, resulting in serious losses.
Low temperature chilling injury of rice: Low temperature chilling injury is a national rice disaster. The growth of early rice in the triple-cropping or double-cropping rice areas in southern China is at the stage from low temperature to high temperature. Early rice planting in meiosis is still in danger of encountering low temperature, which often causes harm. The growth of late rice is in the transition stage from high temperature to low temperature, and improper transplanting date, variety type and agricultural technical measures will cause low temperature damage during heading, flowering and filling. Because it is the cold dew season in South China, the low temperature chilling injury is also called "cold dew wind" in southern rice areas; The middle and lower reaches of the Yangtze River are called "low temperature hazards in autumn"; Northeast China is also called "dumb disaster".
Rice heat damage: during the summer drought, the light is strong, the highest temperature rises above 35℃, and the empty chaff rate increases significantly, so the daily maximum temperature of 35℃ is usually taken as the critical criterion of high temperature damage. Encountering high temperature at flowering stage will dry the flower core, increase empty grains, and encounter high temperature at grain formation stage, which will lead to "high temperature forcing ripening" and reduce production. According to the analysis of climatic data, in the rice growing season in northern China, high temperature is less harmful, and the high temperature of =35℃ appears in some areas, which is not serious. Rice high temperature damage mostly occurs in the south of the Yangtze River, but not seriously in coastal areas, mostly in Zhejiang and western Fujian, Jiangxi, Hunan and northeastern Guangdong.
Typhoon hazard: Typhoon attack is usually a storm hazard. Where typhoons pass, rice often lodging, the heaviest loss, can reduce production by half. Yield reduction by yellow ripening and lodging 1? 20% In addition, typhoons and rainstorms cause floods, which directly invade farmland and form floods; After the typhoon, rice plants were damaged, which led to the occurrence of rice leaf blight, which was even more harmful. However, in the non-coastal provinces of southern China, the summer drought is severe. After the typhoon, the wind in these areas was not very strong, but the rain brought by the typhoon lifted the drought. Typhoon is not only harmless to drought, but also beneficial to rice production.