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    Low-elevation seeds collected 6 and 2 weeks before assumed natural seed fall were stratified 1, 2, 4, 8, 16, 32, 64, and 123 days and germinated in the laboratory. Germinated seeds from all stratification periods were sown at the same time in the nursery bed. Germination and seedling measurements were taken over two growing seasons.

    Early collection gave smaller seeds, reduced germination percentage, and yielded smaller seedlings. Reduced seedling size appeared to be related to reduced seed weight.

    Germination rates of both early- and late-collected seeds increased with increased stratification, but the response of late-collected seeds was greater. When time to 50 percent of total germination and length of stratification both were expressed in logs, the response was linear over the ranqe of stratification periods. Stratification beyond about 30 days was detrimental to total germination of early-collected seeds.

    Total height of lst-year seedlings was linearly related to the log of stratification period only for late-collected seeds. The effect was small and not present by the end of the 2d year. Stratification appeared to increase lst-year seedling size through its effect on hypocotyl extension. Epicotyl elongation rates during the exponential phase of elongation and elongation period were not affected by stratification period.

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    Sorensen, Frank C. 1980. Effect of date of cone collection and stratification period on germination and growth of Douglas-fir seeds and seedlings. Res. Note PNW-RN-346. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 11 p


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    Germination (seed), seeding date, stratification (seed), cone collection, seed weights, seedling growth, Douglas-fir, Pseudotsuga menziesii

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