School of Biological Sciences, University of East Anglia, Norwich.
Planta. 1969 Dec;84(4):353-7. doi: 10.1007/BF00396427.
The effect of varying calcium concentration in the medium on the potassium flux into the exudate has been studied. In media of low ionic strength (o.1 mM KCl) the potassium flux, J K, was significantly increased by increasing the calcium concentration of the medium. But in higher ionic strength media (10 mM) KCl) there was no increase in J K as the calcium concentration of the medium was increased. The effect of external sodium concentration on J K was also studied. These results are discussed in relation to present theories of salt and water movement into the plant root. It is concluded that two pathways potentially exist for movement of salts to the exudate stream: firstly, via a symplasm and secondly, through the cell wall pathway. But is is further concluded that the cell wall pathway, at normal physiological ionic strengths, is not available for salt transport due to co-ion exclusion by the fixed negative charges.
已经研究了介质中钙浓度的变化对钾流入渗出物的影响。在离子强度低的介质（0.1mM KCl）中，通过增加介质中的钙浓度，钾通量 JK 显著增加。但在较高离子强度的介质（10mM KCl）中，随着介质中钙浓度的增加，JK 没有增加。还研究了外部钠离子浓度对 JK 的影响。这些结果与目前关于盐和水进入植物根系的理论进行了讨论。得出的结论是，盐向渗出物流移动存在两种潜在途径：首先，通过共质体，其次，通过细胞壁途径。但进一步的结论是，由于固定负电荷的同离子排斥，在正常生理离子强度下，细胞壁途径不适用于盐的运输。
