The role of apical dominance in paradormancy of temperate woody plants: a reappraisal

摘要

Paradormancy, also known as summer dormancy, is the temporary dormancy which precedes winter or endodormancy in temperate woody plants. Apical dominance is thought to play a primary role in the paradormancy of current lateral buds which normally donot grow out until the following spring after overwintering. In order to test apical dominance, periodic decapitation and defoliation beginning with early spring flushing and extending through the 1997 and 1998 growing season were carried out in or nearColumbus, Ohio, USA, on white ash (Fraxinus americana), green ash (F. pennsylvanica var. subintegerrima), red oak (Quercus borealis [Q. rubra]), black walnut (Juglans nigra), pignut hickory (Carya glabra and C. ovalis), shagbark hickory (C. ovata), sweetgum (Liquidambar styraciflua), cottonwood (Populus deltoides), sugar maple (Acer saccharum), hybrid silver/red maple (A. saccharinum X A. rubrum) and white pine (Pinus strobus), ranging in age from 6 to 50-60 years. Significant decapitation and defoliation release of current lateral buds into growing branches was found only in hybrid silver/red maple and red oak, respectively. In a greenhouse study of 1-year-old sugar maple and green ash seedlings, a significant response was found only in the latter. The lack of response in most of the species analysed indicates that other inhibitory influences may be overriding that of apical dominance and suggests that apical dominance does not play the primary role in paradormancy in some temperate woody species.