The electrical impedance spectroscopy of Scots pine (Pinus sylvestris L.) shoots in relation to cold acclimation

Electrical impedance spectroscopy (EIS) was applied to stems of Scots pine (Pinus sylvestris L,) in a provenance field trial during frost hardening to find an EIS parameter for assessing frost hardiness (FH) without a control led freezing test. The FH of stems and needles assessed by controlled freez ing tests was compared with the equivalent circuit EIS parameters of a dist ributed model of stems (not exposed to controlled freezing treatment) and w ith dry matter (DM) content of stems. Significant differences in the equiva lent circuit parameters, FH and DM content were found between provenances, The relaxation time (tau (1)), describing the peak of the high frequency ar e of the impedance spectrum, and the intracellular resistance (r(i)) of ste ms increased with increasing FH, According to the linear regression, the co efficient of determination (R-2) between the FH of stems and needles with t au (1) of the stem was 0.87 and 0.89, and with r(i) of the stem 0.74 and 0. 85, respectively, The relation between FH and tau (1) changed with the degr ee of hardiness, The highest coefficient of determination was 0.95 in Septe mber when the FH of needles, ranging from -10 degreesC to -25 degreesC, was predicted with an accuracy of +/- 2.0 degreesC, The resistance parameter r (2), describing the width of the low frequency are of the impedance spectru m, decreased prior to and during the initial hardening: significant differe nces were found between provenances, This indicates that r(2) was not relat ed to frost hardening per se. It is concluded that it is possible to distin guish the hardening patterns of different provenances by tau (1) in the rap id phase of hardening without controlled freezing tests.