Chlorophyll fluorescence characteristics, performance and survival of freshly lifted and cold stored Douglas fir seedlings

The physiological condition of three-year-old Douglas fir [Pseudotsuga menz iesii (Mirb.) Franco] was periodically assessed from October to May 1998/19 99 during propagation of seedlings in an Irish nursery. Seedling physiologi cal status was evaluated in situ using determinations of chlorophyll fluore scence and plant water status. Pre- and post-cold stored (either -2 degrees C or +0.5 degreesC) plant vitality was examined using determinations of roo t growth potential (RGP), root electrolyte leakage (REL), shoot water conte nt and chlorophyll fluorescence. Data obtained from freshly lifted and cold stored stock showed that chlorophyll fluorescence provides a reliable (non -destructive) method of evaluating a seedlings potential field performance in both pre-lift (direct planting) and post-storage (outplanting) situation s. Variations in survival and an index of plant health were paralleled by i nverse changes in the effective quantum yield of photosystem II (Phi PSII) from November to April. Significant positive non-linear relationships were found between RGP and Phi PSII, though they were of limited predictive abil ity in terms of outplanting performance. Post-storage fluorescence assessme nts indicated down-regulation and/or damage of the plants photosynthetic li ght-harvesting complex, which depended on storage temperature and duration.