© 1991 Heron Publishing—Victoria, Canada
Slash pine bud dormancy as affected by lifting date and root wrenching in the nursery
Karen A. Kainer, Mary L. Duryea, Timothy L. White and Jon D. Johnson
Department of Forestry, University of Florida, Gainesville, FL 32611, USA / Received August 13, 1990
Summary
Bud dormancy of root wrenched and unwrenched slash pine (Pinus elliottii Engelm.) seedlings growing in a forest nursery was measured on five lifting dates. Determination of bud dormancy was based
on days to budbreak (DBB) under optimal growing conditions, mitotic activity in the apical meristem, chilling hours accumulated,
and bud morphology. Based on DBB, seedlings were most dormant at Lift 2 on November 24 after exposure to 189 hours below 10
°C and 93 hours below 6.7 °C. Mitotic activity in the apical meristem was at its lowest 23 days later at Lift 3, possibly
indicating the period when seedlings are most resistant to transplanting stresses. Multiple wrenching resulted in a slight
shift in the dormancy cycle as wrenched seedlings set bud sooner in the nursery and broke bud sooner at the planting site
in the spring than control seedlings. This implies that wrenched seedlings can be successfully lifted from the nursery earlier
and will initiate spring shoot growth earlier than control seedlings.
