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

Abstract

The physiological condition of three-year-old Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] was periodically assessed from October to May 1998/1999 during propagation of seedlings in an Irish nursery. Seedling physiological status was evaluated in situ using determinations of chlorophyll fluorescence and plant water status. Pre- and post-cold stored (either -2°C or +0.5°C) plant vitality was examined using determinations of root growth potential (RGP), root electrolyte leakage (REL), shoot water content 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) situations. Variations in survival and an index of plant health were paralleled by inverse changes in the effective quantum yield of photosystem II (Φ PSII) from November to April. Significant positive non-linear relationships were found between RGP and Φ PSII, though they were of limited predictive ability in terms of outplanting performance. Post-storage fluorescence assessments indicated down-regulation and/or damage of the plants photosynthetic light-harvesting complex, which depended on storage temperature and duration.