Effects of five different potassium (0 mM ,2 .5 mM ,5 .0 mM ,7 .5 mM and 10 .0 mM ) on the grow th and root morphology index of Chinese cabbage seedling were studied using a pot experiment . The results showed that :with the increase of potassium concentration ,the shoot fresh weight and the whole plant fresh weight of Chinese cabbage seedlings were increased at first and then decreased ,and the highest value occured at the 5 mM .Total root length ,total surface area ,the length and surface area of fine roots (diameters≤0 .4 mm) of Chinese cabbage seedling treated by 5 mM were significantly high‐er than that of other treatments .Moderate levels of potassium to improve total root length ,total surface area ,especially the length and surface area of fine root (diameters≤0 .4 mm) ,thus contributing to the grow th of Chinese cabbage seedling .%通过盆栽实验，研究了5个供钾水平（0、2．5、5．0、7．5和10．0mM）对大白菜苗期生长指标和根系形态参数的影响．结果表明：随钾浓度的提高，大白菜幼苗地上部鲜重和整株鲜重都基本呈现先增后减的趋势，当钾水平为5．0mM 时最高．5．0mM 钾水平处理下大白菜幼苗根系总根长、总表面积，以及细根（直径≤0．4 mm）根长和表面积都显著高于其它处理．适度的钾水平有利于提高大白菜幼苗根系总根长、总表面积，特别是细根（直径≤0．4 mm）根长和表面积，从而有利于大白菜幼苗生长．
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