Agrometeorological Conditions: Rainfall in Jiangnan and South China Helps Increase Soil Moisture
On the 13th, scattered heavy rainfall occurred in Jiangnan, northern Guangxi, and the eastern part of the Southwest region. Among these areas, parts of southern Zhejiang, Fujian, Jiangxi, central and southern Hunan, northern Guangxi, southern Guizhou, the Sichuan Basin, and southern Yunnan received 50-110 mm of rain, while localized areas in Wenzhou, Zhejiang; Ningde, Fujian; Huaihua, Hunan; and Hechi, Guangxi received 150-205 mm.
It is expected that on the 14th, short-duration heavy rainfall will mainly occur in parts of eastern Inner Mongolia, southern North China, western and northern Huanghuai, Jiangnan, South China, and the eastern and southern parts of the Southwest region; among these, hourly rainfall in northern Shandong, Hunan, Jiangxi, southern Zhejiang, Fujian, southern Guangdong, and Yunnan may reach 30-50 mm, with localized areas exceeding 60 mm. In addition, localized areas in northern Xizang, western Qinghai, southern Shanxi, western Shandong, and southern Guangdong will experience thunderstorms, strong winds, or hail.
At present, most late rice in South China is in the three-leaf to transplanting-and-green-recovery stage, while most of Jiangnan and eastern South China are in the tillering stage, with some entering the jointing stage. The tillering stage of rice mainly involves the growth of roots, leaves, and tillers as vegetative organs; it is the main period of vegetative growth and the key period that determines the number of panicles. This period is when rice is relatively sensitive to water; soil moisture content between highly saturated and a shallow water layer is favorable for early tillering, while an overly deep water layer gradually inhibits tillering; conversely, when soil moisture drops below 70% of field capacity, rice tillering begins to be affected.
Heavy rainfall will further help increase soil moisture and store water in reservoirs and ponds, which can meet the water needs of late rice during its growth period. However, localized short-duration heavy rainfall and strong winds may cause rainstorm and flood disasters, resulting in some low-lying farmland being inundated and tall crops lodging or suffering mechanical damage to leaves and stems.
It is recommended that Jiangnan and South China promptly drain field water after rain, improve the crop root growth environment, and apply appropriate topdressing to promote normal crop growth.