Effect of Environment on the Development of Dormancy and Growth of Douglas-Fir Seedlings

Abstract
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) 1st-year-seedlings from seeds collected from stands in central British Columbia and didfferent altitudes in Oregon were grown under a series of artificial environments for 4 months in each of 3 years. Vegetative growth of seedlings from all seed sources was stimulated by 10ng (15 hr.) photo- periods, high (21[degree]C) night temperatures, and moist soil. Early dormancy was induced by short (9 hr.) photoperiods, 10w (3[degree]C) night temperatures, and dry soil.