Effects of storage, temperature, and moisture stress on seed germination and early seedling development of trembling aspen

Abstract

Fresh seed from seven clones of Populustremuloides Michx., and seed from the same collections stored at −18 °C for 1, 6, 12, and 24 months, were germinated at five water potentials (0, −2, −4, −8, and −12 bars; 1 bar = 100 kPa) and two night–day temperature regimes (20–30 °C and 15–25 °C).Germination was not significantly reduced at any moisture stress used, by storage. Average germination of fresh seed at 0 and −2 bars was 94%. Germination at −4 bars was 61% with much variation among clones and between temperature regimes. When the effect of temperature was significant, the 20–30 °C regime was the better. At −8 and −12 bars, little or no germination occurred.Coronet development occurred on at least 85% of the seedlings from all clones, after all storage times, under either germination temperature regime, at moisture stresses up to and including −8 bars. At −12 bars, coronet development occurred much less frequently, and the 20–30 °C temperature regime was the better. Cotyledon expansion occurred on at least 80% of the seedlings at moisture stresses up to and including −4 bars. At −8 and −12 bars, the frequency of cotyledon expansion dropped, and the 20–30 °C temperature regime was the better.