title: Early wound reactions of Japanese maple during winter dormancy: the effect of two contrasting temperature regimes.
abstract: During winter dormancy, temperate trees are capable of only a restricted response to wounding. Depending on the ambient temperature during winter dormancy, wounded trees may start compartmentalization, e.g. by producing inhibitory compounds, but it is thought that processes involving cell proliferation, such as the formation of callus and wound xylem, are delayed until the next growing season. We investigated the effect of two contrasting temperature regimes on early reactions of Acer palmatum trees to wounding during winter bud dormancy. Stems of A. palmatum trees were wounded and stored under an ambient temperature of 4 or 15 °C for 3 weeks during winter bud dormancy. We then studied wound reactions in the living bark, cambial region and xylem. In the 4 °C treatment, wound reactions were virtually absent. In the 15 °C treatment, however, trees reacted to wounding by dieback of the cortex and phloem and by the formation of ligno-suberized layers. In the cambial zone, cambial dieback occurred and callus tissue and wound xylem were formed locally, close to the wound margins. In the xylem, compartmentalization took place by deposition of inhibitory compounds in fibre cells and vessel elements. We conclude that temperature is an important factor in wound reactions during winter dormancy, and may even induce proliferation of callus and wound xylem within a 3-week period. It therefore seems likely that trees that have been wounded during dormancy in areas with mild or warm winters might cope better with wounding, as unlike trees in cold environments, they may compartmentalize wounds even during winter dormancy.
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands Paul.copini@wur.nl.
authors.forename: Paul
authors.initials: P
authors.lastname: Copini
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: den Ouden
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Decuyper
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Godefridus M J
authors.initials: GM
authors.lastname: Mohren
authors.affiliation: Netherlands Food and Consumer Product Safety Authority, National Plant Protection Organization, PO Box 9102, 6700 HC Wageningen, The Netherlands.
authors.forename: Antoon J M
authors.initials: AJ
authors.lastname: Loomans
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Ute
authors.initials: U
authors.lastname: Sass-Klaassen
keywords: Acer palmatum; Japanese maple; local xylem growth; temperature; winter dormancy; wound reactions.