COLD ACCLIMATION PATTERNS OF ACTINIDIA ARGUTE CULTIVARS IN A TEMPERATE CLIMATE ZONE

The kiwi berry, Actinidia arguta Planch is gaining importance in temperate Europe. Warm transient intervals during the winter season can initiate cold deacclimation and bud break of woody plants. Most A. argute cultivars are characterised by an early bud burst which may result in horticultural limitations due to a high sensitivity to spring frost of these young shoots/inflorescences.
The evolution of bud dormancy was observed in two Actinidia argute ‘Weiki’ and ‘Geneva’ cultivars. From September through mid-October the final 30-day shooting percentage (FS) was low. Between mid-October and mid-December a steep rise in FS indicates that bud endodormancy was broken. ‘Weiki’ appears to have a lesser need for cold exposure in order to release it from dormancy.
The seasonal pattern of cold acclimation and deacclimation was determined for both cultivars using the electrolyte leakage test. Maximal cold tolerance was achieved in midwinter. In early spring cold tolerance of the buds declined again. ‘Geneva’ was more cold tolerant than ‘Weiki’.