A forcing solution containing 200 mg 8-hydroxyquinoline citrate per liter and 2% sucrose has been demonstrated to extend the season for obtaining softwood growth suitable for use as explants in micropropagation (Yang & Read 1989). Forcing dormant woody stems in the off-season in this fashion also enhances the macropropagation of woody plant species by providing softwood outgrowth that can be rooted as softwood cuttings. GA3, IBA, IAA and NAA were incorporated into softwood growth which was later used as cuttings for rooting by adding plant growth regulators at various concentrations to the forcing solution. GA3 incorporated into the forcing solution hastened bud break, increased shoot elongation, but inhibited rooting of softwood cuttings taken from stems forced in this manner. IBA, IAA and NAA in the forcing solution exhibited typical auxin effects on rooting of cuttings by increasing root number per cutting and root elongation. In order to expedite macropropagation of woody plants, GA3 and IBA were added SEQUENTIALLY to the forcing solution. Addition of IBA to fresh forcing solution following initial use of GA3 in the forcing solution counteracted the negative effects of GA3 and stimulated rooting. This protocol is proposed as a method to assist propagation in rooting difficult species by softwood cuttings in the off-season.
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