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Long-nights and Moisture Stress Affect Douglas-fir Seedling Growth, Cold Hardiness, Dormancy and Root Growth Potential

Author(s) or contact(s): D.G. Simpson
Source: Research Branch
Subject: Seedling Performance
Series: FRDA Report
Other details:  Published 1990. Hardcopy is available.


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 5C 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)

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Updated July 24, 2015