© 1992 Heron Publishing—Victoria, Canada
Gibberellin A4/7 promotes cone production on potted grafts of
eastern white pine
Rong H. Ho (1) and Frank Schnekenburger (2)
1. Ontario Forest Research Institute, Ministry of Natural Resources, c/o Horticultural Science, University of Guelph, Guelph,
Ontario N1G 2W1, Canada / 2. Orono Nursery, Central Region, Ministry of Natural Resources, Orono, Ontario L0B 1M0, Canada / Received November 22, 1991
Summary
Potted grafts of eastern white pine (Pinus strobus L.) growing in a heated greenhouse were sprayed weekly with 0, 250 or 500 mg l–1 of gibberellin A4/7 for four different 6-week periods between mid-May and mid-September. At different periods, gibberellin A4/7 concentrations of 250 and 500 mg l–1 were effective in promoting pollen- and seed-cone production. Spraying in May and June, during the period of rapid terminal
shoot elongation, significantly increased pollen-cone production, whereas spraying in August and September, about a month
after terminal shoot elongation, significantly increased seed-cone production.
