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Proceedings of Past Forest Nursery Association Meetings:

Regulation of Seedling Height in Container-Grown Spruce Using Photoperiod Control
Eastham, A.M.
1990: Roseburg, OR
In 1989, container-grown white x Sitka spruce (Sxs) seedlings were subjected to a 15h day, either static or dynamic method of blackout treatment, for four weeks to promote budset and regulate height. The blackout treated seedlings were shorter, and had less shoot mass compared to controls without any effect on stem diameter. Control seedlings acquired cold-hardiness slower than blackout treated seedlings, and the dynamic method acquired cold-hardiness slower than the static method. Under controlled conditions, days to budbreak in spring was three days earlier for blackout treated seedlings compared to controls. In 1988, a larger experiment with six seedlots and 12 blackout treatments, applied using dynamic method, was conducted which included the same seedlot as in 1989 and results are compared. All seedlings were lifted and frozen stored. In May 1989, all treatments for all seedlots were outplanted in nursery beds and four seedlots were also planted in their respective regions. First year field assessments indicated a reduction in height growth with 13 h daylength for Engelmann spruce, but not for white x Sitka spruce seedlings. Blackout treatments had little or no effect on phenology.
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