Propagation Techniques for a Spineless Acacia wrightii

in HortScience
Authors:
Donita L. BryanDepartment of Horticultural Sciences, Texas A & M University, MS 2133, College Station, TX 77843-2133

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Michael A. ArnoldDepartment of Horticultural Sciences, Texas A & M University, MS 2133, College Station, TX 77843-2133

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R. Daniel LinebergerDepartment of Horticultural Sciences, Texas A & M University, MS 2133, College Station, TX 77843-2133

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W. Todd WatsonDepartment of Horticultural Sciences, Texas A & M University, MS 2133, College Station, TX 77843-2133

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Three spineless phenotypes of Acacia wrightii G. Bentham ex A. Gray were identified with aesthetic landscape potential. Experiments in seed, cutting, grafting, and tissue culture propagation were undertaken to perpetuate this desired spineless phenotype. Germination percentages for mechanically scarified seeds ranged from 33% to 94%, however yield of spineless seedlings was low (0% to 34%). Sulfuric acid scarification for 10, 20, 30, or 60 minutes hastened and unified germination compared to nontreated seeds by 7 to 8 days. Vegetative propagation was successful for softwood cuttings. Rooting measures increased with auxin (2:1 indole butyric acid to naphthalene acetic acid) concentrations from 0 to 15000 mg·L–1, with maximum rooting percentage (70%), root number (9.2), and root length (12.4 cm) per softwood cutting at 15000 mg·L–1 auxin 8 weeks after treatment. Rooting was not successful for semi-hardwood or hardwood cuttings. Whip-and-tongue or T-bud grafting was not successful. Tissue culture of shoots from in vitro germinated seedlings indicated that shoot proliferation was greatest in Murashige and Skoog (MS) medium with 15 μm zeatin. The number of shoots that rooted in vitro increased with increasing concentrations of indole-3-butyric acid from 0 to 25 μm.

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