II. Freezing tolerance offall-planted seedlings and morphological development offall- and spring-planted seedlings

摘要: Application. The freezing tolerance and subsequent first year morphological development of fall-planted western red cedar seedlings will be improved by the use a short-day nursery cultural treatment. Fall planting result in better root de- velopment for potential spring drought conditions. Nursery treatments used to "harden" spring-planted not improve their growth survival. Abstract. Western (Thuja plicata Dorm) from six (i.e., long-day wet (LDW), moderate (LDM), dry (LDD), (SDW), (SDM) (SDD)) were fall- on field site coastal British Columbia. Fall-planted monitored (expressed as temperatures causing 50% foliage electrolyte leakage, II,,) throughout fail, winter early spring. Both spring- planted populations over growing season. Short-day, compared long-day, either greater or comparable (lower II,, temperatures) fall deacclimated slower SDD treatment had greatest decrease response temperature events. All similar seasonal minimum tempera- tures, measured just prior deacclimation late One month after planting, LDW among treatments, while SDM treatments. fall-, seedlings, diameter, but shorter height one planting. identical shoot However, SDW continued grow during period summer all other slowed stopped. At end season, In general, height, larger diameter than seedlings. survival rates (98-100%) both at season end.