A pot experiment was designed to demonstrate that the parallel, single-frequency detection of electrical capacitance (C R), impedance phase angle (Φ R), and electrical conductance (G R) in root-substrate systems was an adequate method for monitoring root growth and some aspects of stress response in situ. The wheat cultivars 'Hombar' and 'TC33' were grown in a rhyolite-vermiculite mixture under control, and low, medium, and high alkaline (Na 2 CO 3) conditions with regular measurement of electrical parameters. The photochemical efficiency (F v /F m) and SPAD chlorophyll content were recorded nonintrusively; the green leaf area (GLA), shoot dry mass (SDM), root dry mass (RDM), and root membrane stability index (MSI) were determined after harvest. C R progressively decreased with increasing alkalinity due to impeded root growth. Strong linear C R-RDM relationships (R 2 = 0.883-0.940) were obtained for the cultivars. Stress reduced |Φ R |, presumably due to the altered membrane properties and anatomy of the roots, including primarily enhanced lignification. G R was not reduced by alkalinity, implying the increasing symplastic conductivity caused by the higher electrolyte leakage indicated by decreasing root MSI. F v /F m , SPAD value, GLA, and SDM showed decreasing trends with increasing alkalinity. Cultivar 'TC33' was comparatively sensitive to high alkalinity, as shown by the greater relative decrease in C R , SDM, and RDM under stress, and by the significantly lower MSI and higher (moderately reduced) |Φ R | compared to the values obtained for 'Hombar'. Electrical root characterization proved to be an efficient non-intrusive technique for studying root growth and stress responses, and for assessing plant stress tolerance in pot experiments.