Cold Acclimation in Cornus stolonifera under Natural and Controlled Photoperiod and Temperature

Abstract

Seasonal changes in the cold resistance of the living bark of red-osier dogwood (Cornus stolonifera Michx.) were characterized. Concomitant observations were made of dormancy, bark pigmentation, rest period, and leaf abscission. Cold acclimation proceeded in 2 steps during autumn and ultimately reached a level below -125 F. Plants subjected to decreasing photoperiod and temperature in controlled environment chambers were also induced to acclimate to below -100 F. Plants subjected to decreasing photoperiod alone did not appreciably acclimate to cold, while those subjected to decreasing temperatures alone acclimated only slightly. When a rest period induced by short days preceded exposure to gradually decreasing temperatures, the cold acclimation was rapid and substantial. Cold-acclimated plants maintained a high degree of cold resistance long after the chilling requirements for breaking the rest period had been satisfied. Of the visible phenological changes observed, red bark pigmentation was correlated most closely with cold acclimation.