ROOT AND SHOOT GROWTH PERIODICITY OF GREEN ASH, SCARLET OAK, TURKISH HAZELNUT, AND TREE LILAC

The objectives of this study were to determine root and shoot growth p eriodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish h azelnut), and Syringa reticulata (Blume) Hara 'Ivory Silk' (tree lilac ) trees and to evaluate three methods of root growth periodicity measu rement. Two methods were evaluated using a rhizotron. One method measu red the extension rate (RE) of individual roots, and the second method measured change in root length (RL) against an observation grid. A th ird method, using periodic counts of new roots present on minirhizotro ns (MR), was also evaluated. RE showed the least variability among ind ividual trees. Shoot growth began before or simultaneously with the be ginning of root growth for all species with all roof growth measuremen t methods. All species had concurrent shoot and root growth, and no di stinct alternating growth patterns were evident when root growth was m easured by RE. Alternating root and shoot growth was evident, however, when root growth was measured by RC and MR, RE measured extension rat e of larger diameter lateral roots, RL, measured increase in root leng th 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.