Flower Stimulation Treatments in a Loblolly Pine Seed Orchard

Abstract

Abstract Flowering in conifer seed orchards may be sporadic and insufficient to meet reforestation needs at early ages. Consequently, considerable effort has been made to develop cultural treatments to enhance flowering in operational seed orchards. For a number of species, flower-promoting technology is well-defined. This study evaluated two known technologies, currently in use for other species, for flower-promoting effects in loblolly pine (Pinus taeda L.). A replicated experiment was installed in a 10-year-old, second-generation loblolly pine seed orchard at Lyons, GA. Overlapping, saw-cut girdles and stem-injected GA4/7 were applied alone, and in combination, to main boles of ramets of four clones. Timing of treatments was evaluated using four treatment dates. All treatments significantly enhanced female flower production, relative to controls, although girdling was clearly the most effective single treatment. There was no treatment effect on pollen production. Timing of treatment is important but may require evaluation on a site-by-site basis. Tree health 1 year after treatment was excellent, although clonal sensitivity to some treatments was noted. Use of flower stimulation techniques is recommended, particularly for younger loblolly pine orchards. South J. Appl. For. 15(1):44-50.