Canadian Forest Service Publications
Influence of nursery culture on western red cedar: II. freezing tolerance of fall-planted seedlings and morphological development of fall- and spring-planted seedlings. 1994. Folk, R.S.; Grossmickle, S.C.; Major, J.E.; Arnott, J.T. New Forests 8: 231-247.
Issued by: Pacific Forestry Centre
Catalog ID: 3517
Availability: PDF (request by e-mail)
Western red cedar (Thuja plicata Donn) seedlings from six nursery cultural treatments (i.e., long-day wet (LDW), long-day moderate (LDM), long-day dry (LDD), short-day wet (SDW), short-day moderate (SDM) and short-day dry (SDD)) were fall- and spring-planted on a field site in coastal British Columbia. Fall-planted seedlings were monitored for freezing tolerance (expressed as the temperatures causing 50% foliage electrolyte leakage, II50) throughout the fall, winter and early spring. Both fall- and spring-planted populations were monitored for morphological development over the first growing season. Short-day, compared to long-day, treatments were either greater or comparable in freezing tolerance (lower II50 temperatures) throughout the fall and winter and deacclimated slower in spring. The SDD treatment had the greatest decrease in II50 in response to freezing temperature events. All treatments had similar seasonal minimum II50 temperatures, measured just prior to deacclimation in late winter and early spring. One month after spring field planting, LDW seedlings had the greatest root development among fall-planted treatments, while SDM and SDD seedlings had the greatest root development among spring-planted treatments. The fall-, compared to spring-planted seedlings, had greater root development and diameter, but had shorter height one month after spring field planting. Both populations had identical shoot growth over the first season. However, fall-planted SDW seedlings continued to grow in height during a dry period in late summer while height growth of all other fall and spring treatments slowed or stopped. At the end of the growing season, SDW seedlings had the greatest shoot and root development among fall-planted treatments while LDW seedlings had the greatest morphological development among spring-planted treatments. In general, fall-planted seedlings were shorter in height, but larger in diameter and greater in root development than spring-planted seedlings. All treatments had similar survival rates (98-100%) for both fall- and spring-planted seedlings at season end.