INTERIOR SPRUCE SEEDLINGS COMPARED WITH EMBLINGS PRODUCED FROM SOMATIC EMBRYOGENESIS .1. NURSERY DEVELOPMENT, FALL ACCLIMATION, AND OVER-WINTER STORAGE

Interior spruce (Picea glauca (Moench) Voss X Picea engelmannii Parry) seedlings and emblings (plants produced via somatic embryogenesis tis sue culture) were grown as container 1 + 0 plants. Seedling and emblin g morphological development was monitored during the growing season. N eedle freezing tolerance, days to terminal bud break (DBB(t), root gro wth capacity (RGC), and shoot dry weight fraction (DWF) were monitored during the fall and in frozen storage. Emblings had slower height, di ameter, and root growth rates during the initial 2.5 months in the nur sery. Thereafter, seedlings and emblings had equal height growth rate, while emblings had greater diameter and root growth rates. At the end of the growing season, seedlings and emblings, respectively, had 23.8 and 14.2 cm shoot height, 4.0 and 3.4 mm diameter, and 0.81 and 0.80 g root dry weight. During the fall, DBB(t) of both seedlings and embli ngs decreased, with emblings having a more rapid decrease. Both seedli ngs and emblings showed a similar increase in freezing tolerance. Embl ings had a greater increase in DWF. During the fall, RGC decreased the n increased, with seedlings displaying a greater increase than embling s. While in frozen storage, seedlings and emblings maintained a low DB B(t), and a high RGC and DWF. Freezing tolerance decreased while in fr ozen storage, with the loss more pronounced among seedlings. A degree growth stage model describes the first year cycle of development for s eedlings and emblings. Results indicate that seedlings and emblings ha ve slightly different patterns of first year growth and fall acclimati on. However, both seedlings and emblings were at the end of rest when lifted for frozen storage.