Long-night treatment (16 hours for 4 weeks) reduced height growth of container-grown Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) seedlings by causing the formation of resting terminal buds. Moisture stress caused slight reduction of diameter growth. For between 2 and 14 weeks after long-night treatments ceased, foliage of long-night treated seedlings was approximately 5°C harder than that on seedlings from other treatments. Moisture stress treatments had no effect on cold hardiness. Long-night treated seedlings, which were stored overwinter, flushed sooner and had higher levels of root growth potential than moisture stressed or non-stressed seedlings. The results of these experiments suggest that long nights are more effective than moisture stress treatments in preparing container-grown Douglas-fir seedlings for overwinter storage.
FRDA Research Report 151 (1081 KB)
To view this document you need the current version of
Adobe Acrobat Reader, available free from the
Adobe Web Site.
Updated July 24, 2015