Abstract
Growth and survival of bareroot plants after transplanting is partially a function of the plant's capacity to produce new roots. We conducted an experiment to determine whether application of plant growth regulators (PGRs) or moisture retention materials could modify IAA concentration in roots, new root growth, and above ground plant growth. Bareroot western larch, Englemann spruce, lodgepole pine, and Douglas-fir were treated with Stimroot, ethrel, Hormogel, or Alginate immediately before planting into a raised bed in a greenhouse. All treatments increased IAA content in roots of western larch, Englemann spruce, and Douglas-fir, but only treatments containing IBA increased free IAA in roots of lodgepole pine. Stimroot and Hormogel treatment increased height growth of western larch, lodgepole pine, and Douglas-fir, but only ethrel treatment increased height growth of Englemann spruce. All treatments increased stem diameter growth of western larch. Stimroot increased stem diameter growth rate of Englemann spruce and Douglas-fir, but stem diameter of lodgepole pine was unaffected by all treatments. Our results indicate that application of PGRs or other root-promoting materials to the roots of bareroot conifers before planting has the potential to be a cost-beneficial method for increasing root growth and decreasing transplant shock.
Author notes
We gratefully acknowledge the financial support of the National Research Council of Canada, and the USDA-ARS.
2Research Plant Physiologist. Author to whom all correspondence should be addressed. Telephone: 541-752-9452; fax: 541-750-8764; email [email protected].
3Research Plant Pathologist.