一、苗期“三防”1.盖膜严密,防风灾铺膜时四周挖二、三寸深的小沟,将地膜埋严踩实,既可保持膜下的温湿度,又防止膜下灌风掀起。据太原地区1953—1963十一年气象资料,每年4月份出现八级或八级以上大风天气平均为7天,多者11天,少者2天;5月份平均为5天,多者10天。因此,铺膜时一定要盖严埋实,放苗后将放苗孔用土封严。2.适时播种,防霜冻低温冷害是我省春季另一种常发性自然灾害。一般春季三年两冻。晚霜低温晋南在4月下旬,晋中等地常在5月上、中旬。发生越迟,危害越严重。覆盖棉花出苗快,一般7天左右齐苗,这时最怕晚霜低温。试验表明,未放出地膜外的幼苗不紧贴膜面时,因有薄膜保护,不易受晚霜危害;播种、放苗较早,又早间苗的,因生长壮实,体内 First, the seedling “three defenses” 1. Cover film tight, windbreak disaster Surrounded by digging two or three inches deep trench, the film will be buried under strict real conditions, both to maintain the temperature and humidity under the film, but also to prevent membrane Filling the wind off. According to the eleven-year meteorological data from 1953 to 1963 in Taiyuan, the average annual windy weather of grade eight or above in April was 7 days, with 11 days being the most and 2 days being the less. In May, the average was 5 days and the average was more than 10 days . Therefore, when the film must be covered with strict burial, Fangmiao put Fangmiao soil seal. 2. timely sowing, anti-frost chilling injury is another common spring in our province natural disasters. Generally three years in the spring two frozen. Night frost low temperature Jinnan in late April, Jinzhong often in May, mid. The later, the more serious the harm. Covering cotton seedling fast, usually about 7 days Qi Miao, then fear the night frost low temperature. Experiments show that the seedlings not released outside the membrane is not close to the membrane surface, due to the protection of thin film, less susceptible to late frost damage; sowing, Fangmiao earlier, and early seedlings, due to strong growth, in vivo