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Abstract

This study investigated the influence of temperature on the germination of red pine (Pinus resinosa Ait.) seed. Three aspects of the temperature-germination relationship were addressed. First, the influence of temperature on the rate of germination and percentage germination was studied to test the hypothesis that low ambient temperatures inhibit the northward migration of red pine. Second, a model relating degree days to accumulated germination was developed. Third, the role of prechilling red pine seed was explored.

Temperatures of 15 C or greater were required for germination of 80% or more of the seeds, which means that germination capacity is not limiting the expansion of the range of the red pine. Temperatures greater than 10 C were required for completion of the germination process of unchilled seeds. Approximately 75% of the variance in the germination data was explained using a simple stepwise linear regression using accumulated thermal time (degree days). Prechilling the seeds (2-5 C) resulted in increased germination at temperatures of 10 and 12.5 C compared with unchilled seeds (78% vs. 26%). Prechilling also reduced the mean germination time by at least 1 day, even at the optimum temperature (25 C).