photosynthetic efficiency of frozen-stored picea glauca seedlings in relation to root pruning, root growth, and shoot moisture stress / by s. j. colombo. --
abstract
this study examines the influence of duration of frozen
storage (-2 c) and root pruning on photosynthetic efficiency,
shoot moisture stress and root growth of white spruce (picea
glauca (moench) voss) seedlings planted in a glasshouse.
photosynthetic efficiency was measured using infra-red gas
analysis, and shoot moisture stress by the pressure chamber
technique. root growth was determined using trees planted in
glass-faced root boxes.
photosynthetic efficiency of root pruned and non-pruned
trees which were not frozen was significantly greater 2 and 4-
weeks after planting than that of stock frozen 92 days. rates
of photosynthesis of trees which had been frozen for 50 days
were inexplicably lower than other storage treatments up to four weeks after planting. after six weeks photosynthetic
efficiency was high regardless of duration of storage. shoot
moisture stress of seedlings stored 92 days remained significantly
greater than non-frozen stock throughout the experiment, in
spite of greater root growth by those frozen 92 days. root
pruning had a detrimental influence on all aspects of seedling
physiology examined: photosynthetic efficiency was lower,
shoot moisture stress greater and root growth was slower than
in non-root pruned seedlings. root growth was not strongly
correlated with photosynthetic efficiency.
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- retrospective theses [1604]