Keepability of Pennsylvania versus West Coast Grown Douglas-Fir Christmas Trees: Genotypic Variation in Relation to Subfreezing Temperatures
Abstract Cut Douglas-fir Christmas trees grown in Pennsylvania from Rocky Mountain seed sources and coastal trees grown in the Pacific Northwest and shipped into Pennsylvania were compared for keepability. Following various cold treatments, the cut ends of trees were placed in water in an indoor display area. Coastal trees placed in a freezer at - 29°C for 24 h had 89 ± 5.1% (mean ± standard error) needle loss after one day of display, while Rocky Mountain origin trees exhibited only 3 ± 2.0% needle loss after 1 day and 50 ± 5.6% needle loss after 18 days. Coastal produced trees exposed to temperatures > - 12°C had 50 ± 9.8% needle loss at the end of the experiment, while Rocky Mountain trees ended with 22 ± 3.2% needle loss. Four additional treatments consisted of trees placed on an outdoor lot and periodically moved indoors to simulate Christmas tree market activity. Again, there was a significant difference between trees from coastal and Rocky Mountain sources, with 57.2 ± 4.3% and 11.8 ± 1.2% needle loss after 3 days, respectively. By the end of the 23 day experiment, the coastal trees were essentially devoid of needles, whereas Rocky Mountain trees had an average of only 20% needle loss. Coastal trees also exhibited a very noticeable loss of color and lustre. North. J. Appl. For. 7:86-89, June 1990.