Freezing injury and shoot elongation in balsam fir

Abstract

Three-year-old seedlings of balsam fir (Abiesbalsamea (L.) Mill.) representing provenances with different rates of shoot growth initiation were exposed to four temperatures between −3.3 and −8.5 °C at two different times during shoot elongation. Exposure at −3.3 °C resulted in no bud, shoot, or leaf injury. Exposure at −8.5 °C resulted in injury to 53% of 2000 buds and shoots tested. Differences in provenance and in timing of exposure were significant at lower temperatures. Freezing injury was largely a function of the developmental stage of buds and shoots at each temperature of −4.5 °C or lower. One-year-old leaves were severely damaged at lower temperatures and effects of provenance and timing of exposure were present.