FACTORS AFFECTING THE VIABILITY AND GERMINATION BEHAVIOR OF CONIFEROUS SEED. IV. STRATIFICATION PERIOD AND INCUBATION TEMPERATURE, PSEUDOTSUGA MENZESII (MIRB.) FRANCO

Abstract

Douglas fir seed from 10 geographic sources was stratified for periods of up to 150 days in length and incubated at 10, 15, 20, 25, and 30 °C. The relatively rapid germination at 10 °C following the longer periods of stratification indicates advantages for nurseries subject to cold spring weather. The observed decrease of germination per cent (and apparent germinative capacity) after long periods of stratification of some lots suggests that long stratification may be used as a test of vigor or durability. Separation of Coastal seed lots from Interior seed lots, and further separation of these into broad classes appears possible on the basis of germination behavior at 10 °C or 15 °C following a specific period of stratification such as 20 or 40 days.