Seasonal changes in intensity of bud dormancy in loblolly pine seedlings

The terminal buds of six-month-old loblolly pine (Pinus taeda L.) seedlings remained closed for approximately six months, although bud dormancy, as measured by rate of bud break in a standard greenhouse environment, was only exhibited for about one month. The peak of bud dormancy was in December for seedlings grown near Auburn, Alabama. However, the timing and intensity varied with seed source and may have been affected by the warm fall temperatures. Seedlings from the more northern provenances entered dormancy first and reached a deeper state of dormancy than seedlings from southern provenances. The rate of shoot elongation was not consistently related to the rate of bud break.