Frost hardiness of dormant Salix shoots

Abstract

The frost hardiness of dormant stem cuttings of cultivated Salix, representing a range of species and clones, was determined. Plants were subjected to a standardized artificial hardening regime, and frost hardiness was determined using a standardized freezing method. All the cuttings survived exposure to temperatures of at least ‐ 85°C. Freezing tolerance was concluded to be the most important winter survival mechanism for all cultivated Salix species. Primordia in the axillary buds, the secondary cambium and the root initiation cells all tolerated the imposed low‐temperature stress. Field observations, together with the experimental results, suggest that winter damage is because of incomplete winter acclimation rather than inherent inability to develop adequate tolerance to low temperature stress.