Canadian Forest Service Publications
Douglas-fir genotypic response to seed stratification. 1995. Edwards, D.G.W.; El-Kassaby, Y.A. Seed Science and Technology 23: 771-778.
Available from: Pacific Forestry Centre
Catalog ID: 4375
CFS Availability: PDF (download)
Douglas-fir responses to stratification duration were studied using wind-pollinated seeds from 15 seed-orchard clones. Germinative parameters (germination capacity, peak value, germination value, and germination rate and speed) were evaluated in response to four stratification periods (0, 3, 5, and 7 weeks). Significant differences among germinative parameters were observed indicating that the five-week stratification period represents the most appropriate treatment in minimizing variation caused by genetic differences. The results indicate that the International Seed Testing Association (ISTA) rules, which focus only on germination capacity, do not provide an adequate expression of seedlot dormancy, and since the rules are aimed at bulked seedlots, genetic differences, which can be large in heterogenous forest tree seeds, are hidden. The results also demonstrate that extended stratification not only reduces the time in which seedlings become established, but also reduces seedling-emergence variation among parental lines.
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