“寒露风”在湖南乃至江南各地一般于9月中下旬至10月上旬出现。因为“寒露”前后,北方冷空气逐渐向南侵袭,形成低温阴雨或干燥的冷北风,也就是进入秋后出现的第一次强冷空气所造成的秋季低温天气。 晚稻抽穗扬花期最适温度为25～30℃。其中常规晚粳遇到连续3天日平均气温低于20℃,常规晚籼遇到连续3天日平均气温低于22℃,杂交晚籼遇到连续3天日平均气温低于23C,再加上北风大,日照少,雨日多,对上述各类型晚稻的扬花受精极为不利。如抽穗期遇上,会造成抽穗速度 “Cold dew wind” in Hunan and even the southern part of the general in late September to early October appear. Because before and after the “cold dew”, the north cold air gradually invaded south, forming cold rainy or dry cold north wind, that is, into the fall of the first strong cold air caused by the autumn cold weather. The optimum temperature for heading and flowering of late rice was 25 ~ 30 ℃. Conventional late japonica encountered three days average daily temperature below 20 ℃, conventional late indications met the average daily temperature of three consecutive days less than 22 ℃, hybrid late indications encountered three consecutive days average daily temperature below 23C, plus On the north wind, less sunshine, rainy days, the above types of late rice flowering fertilization is extremely unfavorable. Such as heading encounter, will result in heading speed