Stratification period and germination of Douglas-fir seed from Oregon seed orchards: two case studies.

Abstract

Effect of stratification period (S) and incubation temperature (T) on germination be- havior were tested by using two groups of Douglas-fir orchard seedlots that had given low germination percentages in standard tests. One group of seedlots that had experienced different cone-drying regimes, but otherwise were treated comparably, were germinated at T = 15 and 25 °C after S of 21, 42, and 84 days. Cone-drying conditions affected germination behavior. Particularly, low-humidity, high-temperature drying decreased the rate and percentage of germination, but if seeds were given 84-day S, then germination was good, even at 15 °C. A second group of five seed lots represented three elevational blocks from one orchard, two blocks sampled in 2 years. Seedlots were tested as above, except S of 21 days was omitted. Year of collection and, to a lesser extent, orchard block affected germination behavior, but in all cases germination was 90 percent or more, and rate and uniformity were good if seeds received 84 days of S. At 15 °C incubation, only 84 days of S gave satisfactory germination. At 25 °C, 21 days of S gave satisfactory percentage of germination, but rate and uniformity were much improved by longer stratification. Preliminary recommendations for stratification are given and discussed for different germination temperatures.

Citation

Sorenson, Frank C. 1991. Stratification period and germination of Douglas-fir seed from Oregon seed orchards: two case studies. Res. Note PNW-RN-499. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 24 p