中文摘要：

【目的】为探讨水稻幼苗根系NH4+、K+吸收的交互作用，深化水稻养分吸收理论，【方法】采用溶液培养的方法，对低钾及高钾浓度下水稻在有铵和无铵时的K+吸收动力学特征进行了研究，对不同钾浓度下水稻根系NH4+的吸收速率进行了比较。【结果】1）当K+<0.2mmol/L时，水稻根系通过高亲和转运系统吸收K+服从Michaelich-Menten动力学方程；NH4+的存在显著降低K+的最大吸收速率(Vmax)，且降幅随着NH4+浓度的增加而增大；NH4+对水稻根表载体与K+的亲和力（Km）影响较小，在1.62mmol/LNH4+浓度下，水稻品种齐粒丝苗和沪科3号的Km分别下降了12.33%和16.46%，远低于Vmax47.30%和39.21%的降幅。2）当K+>0.5mmol/L时，水稻根系K+低亲和转运系统发挥作用，K+吸收速率随浓度的增加而不断增加，呈不饱和特征；但在相同K+浓度下，水稻根系的K+吸收速率随NH4+浓度的增加而下降。3）水稻根系对NH4+的吸收速率随着NH4+浓度的增加而增加；在相同NH4+浓度下，水稻根系对NH4+的吸收速率受K+浓度的影响很小。【结论】NH4+抑制水稻苗期根系K+的高亲和转运和低亲和转运，NH4+对K+高亲和吸收的影响主要是由于铵竞争细胞膜上的钾载体所致；外界K+浓度的变化对水稻幼苗的NH4+吸收速率影响很小。水稻铵钾的交互作用主要表现在NH4+对K+吸收的抑制作用。

英文摘要：

【Objective】In order to clarify the interaction between NH4+and K+uptake in rice roots at the seedling stage,and to lay a solid basis for fertilizer application in rice production,【Method】we conducted an hydroponic experiment under different NH4+and K+concentrations,and analyzed NH4+and K+uptake rate of rice roots at the seedling stage.【Result】When K+concentration was less than0.2mmol/L,the K+uptake curve through high-affinity transport system(HATS)in rice root followed the Michaelich-Menten equation.NH4+decreased K+uptake rate,the Vmax of K kept decreasing with the increase of NH4+concentration,however,the effect of NH4+on Km was relatively little.Compared with zero NH4+treatment,the Vmax and Km of K+uptake at the1.62mmol/L NH4+application level decreased by47.30%and12.33%in rice variety Qilisimiao(QL),and by39.21%and16.46%in rice variety Huke3(HK3),respectively.When K+concentration was higher than0.5mmol/L,it was mainly absorbed through low-affinity transport system(LATS),in which the uptake rate of K+was kept increasing with the increase of K+concentration,and NH4+greatly decreased the uptake rate of K+-LATS at the same concentration of K+.The uptake rate of NH4+was increased with the increase of NH4+concentration,however,no significant difference was observed in NH4+uptake rate under different concentrations of K+.【Conclusion】NH4+reduced K+uptake both through HATS and LATS of K+;and the effects of NH4+on K+-HATS uptake were mainly due to the competition of NH4+for K+-carrier at the cell membrane;K+had no influence on NH4+absorption.The interactions between NH4+and K absorption in rice root at the seedling stage were mainly because NH4+reduced K+uptake.