sodininkystė ir daržininkystė 25(4)

Fig. 1. Correlation between controlled freezing results (as indicated by root hardiness
(RT 50
for root volume increase) and field data from New York in 2002 (% survival)
1 pav. Koreliacija tarp kontroliuojamo ðalèio rezultatø (ðaknø atsparumas, ðaknø tûrio
padidëjimas RT 50
) ir lauko duomenø Niujorke 2002 metais (iðlikusiø poskiepiø, %)
Electrical impedance (Z) proved to be a very sensitive tool in monitoring for
changes in cell integrity associated to cold stress. The exponential decrease in extracellular
resistance with decreasing temperatures can be described by the equations:
Ro = 44298.23×exp (0.1894×T), Ro = 17798.33×exp (0.1640×T), Ro = 12242.27×exp
(0.1349×T) for the root pieces receiving the 1X, 2X or 3X freeze-thaw cycling
treatments, respectively (Fig. 2). At each of the temperatures, it was obvious that
freeze-thaw cycling was very detrimental to the viability of these root pieces. At
-3°C, two freeze-thaw events were enough to severely injure the root tissue and at
-9°C, one freeze-thaw event was enough to severely reduce root viability to the
extent that further freeze-thaw cycling had no additional effect. Two freeze-thaw
events at -3°C equalled the damage from one freeze-thaw event at -9°C.
Fig. 2 Extracellular resistance (Ro), derived from Z measurements from
Ottawa 3 apple root pieces subjected to one (1X), two (2X) and three (3X)
freeze-thaw cycle treatments
2 pav. Ottawa 3 poskiepio làsteliø atsparumas (Ro), ávertintas Z rodikliais, ið
3 ðaknies daliø, veiktø vienu (1X), dviem (2X) ir trimis ðaldymo-atðildymo ciklais
100