Interpretation of seed-germination parameters

Traditional methods of expressing germination speed have limitations when these estimates are used to gain insights into the consequences of nursery practices on genetic diversity. Limitations result primarily from confounding of viability with vigor, as illustrated by hypothetical and computer simulated examples. Germination characteristics of seeds from 19 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) families were then used to illustrate the advantage of a proposed approach to measuring germination speed, based on proportion of viable seeds germinating by a particular day. This measure is independent of viability. It is demonstrated that fast germination can occur in seedlots where viability is low, and slow germination can occur in seedlots where viability is high.