The objectives of this study were to determine root and shoot growth periodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees and to evaluate three methods of root growth periodicity measurement. Two methods were evaluated using a rhizotron. One method measured the extension rate (RE) ofindividual roots, and the second method measured change in root length (RL) against an observation grid. A third method, using periodic counts of new roots present on minirhizotrons (MR), was also evaluated. RE showed the least variability among individual trees. Shoot growth began before or simultaneously with the beginning of root growth for all species with all root growth measurement methods. All species had concurrent shoot and root growth, and no distinct alternating growth patterns were evident when root growth was measured by RE. Alternating root and shoot growth was evident, however, when root growth was measured by RL and MR. RE measured extension rate of larger diameter lateral roots, RL measured increase in root length of all diameter lateral roots and MR measured new root count of all sizes of lateral and vertical roots. Root growth periodicity patterns differed with the measurement method and the types of roots measured.
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