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土壤温度是调节植物生长和发育的一个重要变量。通过实验观测确定棉花出苗前不同土壤温度对根和芽的生长的影响。将棉花种在长300mm,直径50mm圆柱容器内,在土壤温度为20℃、32℃、38℃三种条件下生长192h。数据表明:在32℃时棉苗的根(173mm)和芽(152mm)最长,其次是20℃时(根130mm和芽82mm),在38℃时棉苗的根(86mm)和芽(50mm)最短。在棉苗生长192h以后,在20℃和38℃条件下的根系长度比在32℃条件下的根系分别短了20%和50%。38℃下棉苗根和芽的长度及干物质量最小。在棉苗生长180h以后,在20℃和38℃条件下的芽长比在32℃条件下的芽长分别短了44%和61%。棉苗在以上3个温度下生长模式相似:开始是线性生长,接着生长速率降低或停止生长。停止生长的时间随温度变化而变化,温度越高生长速率降低越快。土壤温度≥38℃时对出苗不利,因此棉花播种应在苗床土壤温度达到这个温度前完成。此外,在种子中储存的水分和营养物质损耗完之前,苗床应有足够的水分和营养供给种子生长。
Soil temperature is an important variable that regulates plant growth and development. The effects of different soil temperatures on the growth of roots and shoots were determined by experimental observations. The cotton was planted in a cylindrical container with a length of 300mm and a diameter of 50mm. The cotton was grown for 192h under three conditions of soil temperature of 20 ℃, 32 ℃ and 38 ℃. The data showed that the roots (173 mm) and buds (152 mm) of cotton seedlings were the longest at 32 ° C followed by the roots (86 mm) and buds (50 mm ) The shortest. After 192 h of cotton seedling growth, the root length under 20 ℃ and 38 ℃ was 20% and 50% shorter than that under 32 ℃ respectively. The length and dry matter of cotton seedling roots and shoots were the least at 38 ℃. After the cotton seedlings were grown for 180h, the shoot lengths at 20 ℃ and 38 ℃ were 44% and 61% shorter than those at 32 ℃ respectively. Cotton seedling growth patterns are similar at the above three temperatures: the beginning is a linear growth, then the growth rate is reduced or stopped growing. The time to stop growing changes with temperature, the higher the temperature, the faster the growth rate decreases. Soil temperature ≥ 38 ℃ when the emergence of unfavorable, so cotton planting should be completed before the temperature reaches the soil temperature in the seedbed. In addition, the seedbed should have adequate moisture and nutrient supply for seed growth until the moisture and nutrients stored in the seed have been depleted.