Seed lot, nursery, and bud dormancy effects on root electrolyte leakage ofDouglas-fir (Pseudotsuga menziesii) seedlings

The effects of seed lot, nursery culture, and seedling bud dormancy status on root electrolyte leakage (REL) of Douglas-fir (Pseudotsuga menziesii (Mi rb.) France) seedlings were assessed to determine if these factors should b e considered when interpreting REL for seedling quality. The relationships of REL to survival, net photosynthesis (P-n), stomatal conductance (g(wv)), mid-day shoot water potential (Psi(mid)), root growth capacity (RGC), and relative height growth were determined for each factor. Nursery culture had no effect on the relationship between REL and all other measured attribute s. Seed lot affected the relationship between REL and P-n, Psi(mid), and su rvival. However, critical REL (i.e., lowest value associated with detectabl e root damage) and PS80 REL (i.e., level associated with an 80% probability for survival) were similar between seed lots. Bud dormancy status affected the relationship between REL and survival, RGC, and relative height growth . Control levels of REL, critical REL, and PS80 REL decreased as the number of days required for 50% terminal bud break declined. Thus, terminal bud d ormancy status must be known before REL can be used to assess seedling qual ity. If the bud dormancy status of Douglas-fir populations is known, then c ritical and PS80 REL levels may be useful as indices of root damage.