© 1986 Heron Publishing—Victoria, Canada
A morphological index of Quercus seedling ontogeny for use in studies of physiology and growth
P. J. Hanson (1), R. E. Dickson (2), J. G. Isebrands (2), T. R. Crow (2) and R. K. Dixon (3)
1. Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA / 2. North Central Forest Experiment Station, USDA Forest Service, Rhinelander, WI 54501, USA / 3. College of Forestry, University of Minnesota, St. Paul, MN 55108, USA /
Summary
Attempts to relate plant metabolic activity with developmental stage are often hindered by lack of an appropriate developmental
index. Existing indices of morphological development are unsuitable for use with plants having a semideterminate, recurrently
flushing pattern of growth as displayed by Quercus seedlings. We propose the following morphological index (QMI) to define the stages of Quercus seedling ontogeny: (1) radicle emergence; (2) epicotyl emergence from the soil; and (for each flush) (3) termination of elongation
of the second internode, which corresponds with the period of most rapid stem elongation; (4) completion of elongation by
all internodes, which corresponds with the period of most rapid leaf elongation; and (5) completion of elongation of the last
leaf but one, which usually precedes closely the pause between one growth flush and another.
The relationship between QMI and net photosynthesis by individual leaves of Quercus rubra L. seedlings was determined. Net photosynthesis increased with QMI during a flush, but at a particular QMI stage, generally
decreased from one flush to the next.
