Role of stratification, temperature, and light in Fraser fir germination

Fraser fir (Abiesfraseri (Pursh) Poir.) germination was examined as affected by cold–moist stratification, temperature, and light. There were strong interactions among these factors in the germination response. Germination was accelerated by cold–moist stratification and (or) warm germination temperatures. Stratification periods up to 12 weeks improved germination at low temperatures (8-/16-h thermoperiod of 20/10 °C, respectively), whereas 8 weeks was sufficient for seed germinated at high temperatures (30/20 °C). Germination was influenced by temperature regime, but temperature and light sensitivity decreased with increased durations of stratification. Except at low temperatures, a close relationship existed between daily heat input and germination. Maximum germination occurred at 500–600 degree-hours per 24-h cycle. A 1-h daily light treatment during the 8-h temperature cycle broadened the temperature range for optimum germination. For a 42-day germination period, the effect of a daily 1-h light treatment was essentially equivalent to 4 weeks stratification at 4 °C.