Promotion of Flowering in the Pinaceae by Gibberellins |
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| Authors: | STEPHEN D ROSS RICHARD P PHARIS |
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| Institution: | Forestry Research Center, Weyerhaeuser Company, 505 North Pearl Street, Centralia, Washington, 98531, U.S.A., Department of Biology, University of Calgary, Calgary, Alberta, T2N, 1N4, Canada |
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| Abstract: | Flowering was significantly promoted in 4-year-old grafts of mature coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clones by exogenous gibberellins (GAs) A4 and A7 (as a mixture) applied alone and in combination with A5 and A9. Biweekly applications of 400 μg GA4/7 per branch between late March and late June gave a 5-fold increase in ovulate and 3-fold increase in staminate strobilus production over untreated controls. 6N-benzyladenine and 2,3,5-triiodobenzoic acid applied in combination with GAs had no consistent effect on strobilus production. Non-destructive branch girdling, ineffective by itself as a cultural treatment, enhanced the GA benefit to flowering. Exogenous application of GA4/7 is effective and appears to be a practical method for promotion of early and enhanced flowering in grafted Douglas-fir seed orchards. |
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