the complex changes in physiology, metabolism,
structure, and water content associated with cold
acclimation, plants that are actively growing, flowering,
or breaking dormancy typically have little
to no frost tolerance (Sakai, Larcher 1987; Wisniewski
et al. 2003). In the flowering stage open
flowers freeze at –2°C and primary fruits at –1.5°C
(Duralija 2004). Climatic adaptability is conditioned
by properties with more complex hereditary
basis which are very difficult to distinguish (Sherman,
Beckman 2003). Also, mechanisms involved
in frost damage and hardiness have turned out to
be exceedingly complex and many aspects remain
uncertain (Guy 1990; Thomashow 1999). However,
the majority of the adverse effects are caused