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作 者 ：尹晓明;范晓荣;贾莉君;曹云;沈其荣

期 刊 ：植物营养与肥料学报 2005年 11卷 6期 页码：769-773

关键词：微电极；水稻根系；NH4+浓度；膜电位；

Keywords:microelectrodes, riceroots, NH4+concentration, membranepotential,

摘 要 ：利用微电极技术分别测定了2个水稻品种即武育粳3号(粳稻)和扬稻6号(籼稻)幼苗根尖细胞在吸收不同NH4+浓度(0.0250、.05、0.1、0.5、1.0和1.5.mmol/L)下膜电位的变化特征。结果表明,水稻根系吸收NH₄⁺引起膜的去极化,去极化到一定程度出现部分复极化,有一小部分根系还有超极化现象。去极化大小随外界处理液中NH₄⁺浓度的增加而加强,达到一定程度以后趋于平稳,吸收进程符合Michaelis-Menten动力学特征。两个品种产生的去极化程度不同,武育粳3号产生的去极化大小平均为16.5.mV,扬稻6号产生的去极化大小平均为22.6.mV。在低浓度NH₄⁺(<1.0.mmol/L)处理下,扬稻6号对NH₄⁺较敏感,产生的去极化大小平均为17.5.mV,高于武育粳3号(去极化大小平均为10.9.mV),两个品种产生的去极化大小差异显著(p<0.05)。研究结果表明,扬稻6号吸收NH₄⁺的能力比武育粳3号强,这与吸收动力学的结果是一致的。

Abstract:Changes of the plasma membrane potential on root tips of two rice(Oryza sativa L)cultivars,i.e.,Wuyujing 3(Japonica) and Yangdao 6(Indica) were monitored using microelectrodes under different concentrations of NH₄⁺(0.025,0.05,0.1,0.5,1.0 and 1.5 mmol/L).The results were as follows: NH₄⁺ uptake by the roots made plasma membrane(potential) depolarized;however,depolarization to the certain degree,it appeared the partial repolarization and hyperpolarization in some parts of rice roots during the absorption of NH₄⁺.The magnitude of depolarization increased with the increasing of NH₄⁺ concentrations until a stable state.The course of NH₄⁺ uptake process conformed to Michaelis-Menten (kinetics).The two rice cultivars had different depolarization modes in which the average values depolarized were 16.5 mV(Wuyujing3) and 22.6mV(Yangdao 6).Under low concentration of NH₄⁺(<1mmol/L),with its higher average level of depolarization(17.5mV),Yangdao 6 was more sensitive to NH₄⁺ being higher compared to Wuyujing 3(10.7 mV),and there existed a significant difference in the size of depolarization between these two cultivars(p<0.05).This suggested that Yangdao 6 had the stronger capability to take up NH₄⁺ than Wuyujing 3.The results obtained in this experiment were consistent with those of kinetics of NH₄⁺ influx.

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