水稻苗期根系铵钾离子吸收的交互作用研究

【目的】为探讨水稻幼苗根系NH_4~+、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NH_4~+的吸收速率进行了比较。【结果】1)当K~+0.2 mmol/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;NH_4~+的存在显著降低K~+的最大吸收速率(Vmax),且降幅随着NH_4~+浓度的增加而增大;NH_4~+对水稻根表载体与K~+的亲和力(Km)影响较小,在1.62 mmol/L NH_4~+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Vmax 47.30%和39.21%的降幅。2)当K~+0.5 mmol/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NH_4~+浓度的增加而下降。3)水稻根系对NH_4~+的吸收速率随着NH_4~+浓度的增加而增加;在相同NH_4~+浓度下,水稻根系对NH_4~+的吸收速率受K~+浓度的影响很小。【结论】NH_4~+抑制水稻苗期根系K~+的高亲和转运和低亲和转运,NH_4~+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NH_4~+吸收速率影响很小。水稻铵钾的交互作用主要表现在NH_4~+对K~+吸收的抑制作用。

Study on the Interaction Between Ammonium and Potassium Absorption in Rice Roots at the Seedling Stage

【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 than 0.2 mmol/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 the 1.62 mmol/L NH4+ application level decreased by 47.30% and 12.33% in rice variety Qilisimiao(QL), and by 39.21% and16.46% in rice variety Huke 3(HK3), respectively. When K+ concentration was higher than 0.5 mmol/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.