Impedance Spectroscopy in Frost Hardiness Evaluation of Rhododendron Leaves

Impedance spectroscopy was used in studying frost hardiness of leaves of two diploid rhododendron cultivars, Rhododendron L. ‘PJM’ and R. ‘Cunningham’s White’, and their tetraploid derivatives, R. ‘Northern Starburst’ (NSB) and CW4. After the growing season and initial hardening in a greenhouse, plants were subjected to an acclimation regime in a phytotron: 3 consecutive weeks ata5,a1 andˇ28C each. Hardiness was studied with controlled freezing tests before each decrease in temperature and at the end of the experiment, based on data of extracellular resistance re and relaxation time t of the frost-exposed leaves. The correlation of the two estimates was 0.92. Generally, the diploid clones had better frost hardiness than the tetraploid clones. At the end of the experiment, frost hardiness of the diploid ‘PJM’ wasˇ28.78C and that of the tetraploid NSBˇ20.68C. Leaves of the diploid ‘Cunningham’s White’ and of the tetraploidCW4hardenedtoˇ32.08Candˇ20.98C,respectively.Frost hardiness estimatedbyimpedancespectroscopy correlated well with earlier results based on visual scoring (ra 0.81‐0.86) and electrolyte leakage tests (ra 0.84‐0.90), but results from impedance spectroscopy indicated weaker hardiness than the other tests. The diAerence between the results from impedance spectroscopy and the other tests was smaller and more coherent within the ‘Cunningham’s White’ clones than within ‘PJM’ and NSB. Changes in extracellular and intracellular resistance of non-frozen leaves during the acclimation correlated with the changes in frost hardiness of ‘Cunningham’s White’ clones, but not with those of ‘PJM’ and NSB, which belong to another subspecies. # 2000 Annals of Botany Company

[1]  R. Arora,et al.  Comparing Gompertz and Richards Functions to Estimate Freezing Injury in Rhododendron Using Electrolyte Leakage , 1998 .

[2]  K. Foster,et al.  Dielectric properties of tissues and biological materials: a critical review. , 1989, Critical reviews in biomedical engineering.

[3]  J. Palta.  Stress interactions at the cellular and membrane levels , 1990 .

[4]  Tapani Repo,et al.  INFLUENCE OF DIFFERENT ELECTRODES AND TISSUES ON THE IMPEDANCE SPECTRA OF SCOTS PINE SHOOTS , 1994 .

[5]  Ackmann Jj,et al.  Methods of complex impedance measurements in biologic tissue. , 1984 .

[6]  T. Repo,et al.  Cold hardiness of diploid and corresponding autotetraploid rhododendrons , 1999 .

[7]  O. Lindstrom,et al.  Applying the Richards function in freezing tolerance determination with electrolyte and phenolic leakage techniques , 1995 .

[8]  D. Ingram,et al.  Lethal high temperatures for roots of three citrus rootstocks , 1984 .

[9]  Michael F. Thomashow,et al.  PLANT COLD ACCLIMATION: Freezing Tolerance Genes and Regulatory Mechanisms. , 1999, Annual review of plant physiology and plant molecular biology.

[10]  Linda Chalker-Scott,et al.  Exposure to ultraviolet‐B radiation increases cold hardiness in Rhododendron , 1994 .

[11]  Tapani Repo,et al.  Effects of freeze-thaw injury on parameters of distributed electrical circuits of stems and needles of Scots pine seedlings at different stages of acclimation , 1994 .

[12]  L. Fuchigami,et al.  The Relationship of Ethylene and Ethane Production to Tissue Damage in Frozen Rhododendron Leaf Disks , 1986, Journal of the American Society for Horticultural Science.

[13]  Tapani Repo,et al.  Modelling Woody Plant Tissues5 , 1993 .

[14]  O. Junttila,et al.  Cold hardiness of rhododendron cultivars grown in different photoperiods and temperatures , 1999 .

[15]  D. G. Stout.  Effect of Cold Acclimation on Bulk Tissue Electrical Impedance: II. Measurements with Alfalfa and Birdsfoot Trefoil at Nonfreezing Temperatures. , 1988, Plant physiology.

[16]  Stefano Mancuso,et al.  Seasonal dynamics of electrical impedance parameters in shoots and leaves related to rooting ability of olive (Olea europea) cuttings. , 1999, Tree physiology.

[17]  L. Tahvanainen,et al.  Intracellular resistance correlates with initial stage of frost hardening in willow (Salix viminalis) , 1997 .