Electrical impedance analysis in plant tissues: in vivo detection of freezing injury

Abstract

Freezing injury of potato tuber tissue was studied by measuring electrical impedance, in the range of 100 Hz to 800 KHz, while the tissue was subjected to a −3 °C environment. It was found that a greater proportion of total impedance was due to electrode polarization in frozen tissues than in nonfrozen tissues. In frozen tissue, electrode impedance could be so great that tissue impedance could not be measured reliably. Analysis of tissue impedance using complex nonlinear least squares revealed some dynamics of the process of tissue freezing. After 1 h of exposure to freezing conditions, extracellular resistance began a sustained decrease. This can be explained by electrolyte leakage to extracellular space, presumably as a result of membrane injury. The capacitances of both plasma membrane and tonoplast also decreased with freezing. Key words: potato (Solanum tuberosum L.) tuber, electrical impedance, freezing injury, membrane capacitance.