Effects of freeze-thaw injury on parameters of distributed electrical circuits of stems and needles of Scots pine seedlings at different stages of acclimation

Frost hardening and frost injury of both the stems and needles of Scots pine (Pinus sylvestris L.) seedlings were studied by electrical impedance analysis. This impedance analysis was based on equivalent circuits with distributed circuit elements (DCE). A double-DCE model for stems and two single-DCE models for needles provided excellent fit to the experimental impedance data. However, the single-DCE model for needles which takes into account the asymmetry of the impedance arc proved more appropriate than the symmetric model. Several parameters changed in proportion to frost injury. In stems, extracellular resistance and one relaxation time decreased with increasing damage, whereas intracellular resistance remained relatively unchanged