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棉花发芽和出苗需要温度、水分、空气,一般年份温度是主要矛盾。春季气温稳定上升地区,于5厘米地温稳定通过12℃时播种;春季气温多变并有寒流侵袭的地区,于5厘米地温稳定通过14℃时突击播种。棉花发芽的最低温度是10—12℃,最高40℃。在这个范围内温度高发芽快。5厘米地温在18℃时,从播种到出苗需9天,17℃时需11天,16℃时需12天,15℃时需14天,14℃时需18天。种子萌发期较易遭受低温危害,发芽后20—30个小时,对冻害敏感,如在有利的温度条件下发芽48小时后再遇寒冷,其生长发育不会受到很大影响。总之,在墒情合适的情况下,棉花播种后5—7天,5厘米地温保持在14℃以上,躲过冻害敏感期,出苗时赶上5厘米地温在16—18℃或气温17℃以上(气温在17℃两天,出苗既快又
Cotton germination and emergence need temperature, moisture, air, the general year temperature is the main contradiction. Spring temperatures rose steadily in the region, at 5 cm temperature stable by 12 ℃ sowing; spring temperature and cold invasion of the area, 5 cm in temperature stable by 14 ℃ when the surprise sowing. The minimum temperature of cotton germination is 10-12 ℃, the highest 40 ℃. In this range, high temperature germination fast. 5 cm Geothermal temperature at 18 ℃, 9 days from sowing to seedling, 17 ℃ at 11 days, 16 ℃ at 12 days, 15 ℃ at 14 days, 14 ℃ at 18 days. Seed germination is more vulnerable to low temperature damage, 20-30 hours after germination, sensitive to frost damage, such as 48 hours after germination in favorable temperature conditions and then the cold, its growth and development will not be greatly affected. In short, in the right moisture conditions, 5-7 days after sowing cotton, 5 cm ground temperature remained above 14 ℃, escaped the sensitive period of frost damage, to catch up when the emergence of 5 cm ground temperature at 16-18 ℃ or temperature above 17 ℃ ( Two days at 17 ℃, the emergence of both fast and