© 1995 Heron Publishing—Victoria, Canada
Growth and ABA responses of maple seedlings to aluminum
Annick Bertrand (1), Gilles Robitaille (1), Robert Boutin (1) and Paul Nadeau (2)
1. Natural Resources Canada, Canadian Forest Service-Québec Region, P.O. Box 3800, Sainte-Foy, Québec G1V 4C7, Canada / 2. Agriculture and Agri-Food Canada Research Station, 2560 Hochelaga Blvd., Sainte-Foy, Québec G1V 2J3, Canada / Received November 17, 1994
Summary
We assessed the impacts of low pH and 2.0 mM aluminum (Al) on the growth of sugar maple (Acer saccharum Marsh.) seedlings over a 13-week period. At Week 9, total leaf area of Al-treated seedlings was reduced by 27%; however,
by Week 13, leaf area was similar for seedlings in all treatments. None of the other growth parameters examined were negatively
affected by the treatments at either Week 9 or Week 13. The ABA concentration in the xylem sap, which is an indicator of tree
stress in the field, was not affected by any of the treatments and was highest during periods of high evaporative demand in
June and August. We conclude that the duration of exposure to Al is critical when assessing a threshold for Al toxicity because
plants can acclimate to an Al concentration previously considered toxic. Although Al stress did not appear to reduce the vigor
of sugar maple seedlings directly, it could facilitate an inciting factor such as winter frost to induce tree decline.
Keywords:
abscisic acid, Acer saccharum, acidic deposition, soil acidity.
