© 1991 Heron Publishing—Victoria, Canada
Induction of drought resistance by abscisic acid and paclobutrazol in jack pine
J. G. Marshall (1), J. B. Scarratt (2) and E. B. Dumbroff (1, 3)
1. Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 / 2. Forestry Canada, Ontario Region, Sault Ste. Marie, Ontario, Canada P6A 5M7 / 3. Author to whom correspondence and reprint requests should be addressed / Received July 30, 1990
Summary
Pretreatment with root drenches of abscisic acid or paclobutrazol increased the resistance of jack pine (Pinus banksiana Lamb.) seedlings to subsequent prolonged drought. During drought, seedlings pretreated with abscisic acid or paclobutrazol
exhibited rapid stomatal response, more favorable water potentials, enhanced water retention and increased survival compared
with control seedlings. Maximum differences in survival between pretreated and control seedlings were observed late in the
drought period with survival values of 100, 89, and 0% in the abscisic acid, paclobutrazol, and control treatments, respectively.
Paclobutrazol was also effective in protecting seedlings from a combination of intense heat (≥ 40 °C), low humidity, and drought,
with survival values of 89 and 0% for the paclobutrazol-treated and control seedlings, respectively.
