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一是春季气温持续偏低。种子发芽的最适温度为20～30℃。如春季气温偏低,最低温度在5～6℃,持续时间2～3d,造成种子在土壤中滞留时间过长而不能萌发,就可能导致粉种现象的发生。二是春季降水偏多,土壤湿度过大。一般情况下,种子发芽的最适土壤水分为60%。降水量偏多,土壤水分过高,种子吸水膨胀含水量迅速增加;此外,由于土壤含水量增加,种子周围空气流通不畅,造成种子长时间无氧呼吸而不能正常发芽,最终导致粉种。三是早播、低洼地块粉种现象较重。辽西地区由于受多年春旱的影响,有抢墒播种的习惯,平肥地在4月上旬播种,低洼地在4月中旬播种,这期间如遇低温多湿的气
First, the temperature in spring continued to be low. The optimum temperature for seed germination is 20 ~ 30 ℃. If the spring temperature is low, the minimum temperature of 5 ~ 6 ℃, the duration of 2 ~ 3d, resulting in seeds in the soil retention time is too long and can not germinate, it may lead to the occurrence of powder phenomenon. Second, the spring precipitation is too much, the soil humidity is too large. Under normal circumstances, the optimum seed germination of soil moisture is 60%. In addition, due to the increase of soil water content, the air around the seeds is poorly circulated, causing the seeds to breathe for an extended period of time without anaerobic respiration and thus can not normally germinate, which eventually leads to the production of powder. Third, early sowing, low-lying land Fen phenomenon heavier. Due to many years of spring drought in western Liaoning Province, there is a habit of grabbing moisture and sowing seeds. Flat-crop land is sown in early April and low-lying land is sown in mid-April. During this period, low-temperature and humid air