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Abstract

The propagation method and vegetative condition of ‘Northblue’ blueberry (Vaccinium corymbosum L.) stock plants influenced microshoot production in vitro and root formation on leaf-bud cuttings. In tissue culture (TC), explants from TC-derived stock plants produced longer shoots than explants from leaf-bud, standard- (ST-) derived stock on either Zimmerman’s (Zimm) medium at pH 4.8, Lloyd and McCown’s woody plant medium (WPM) at pH 4.8 or pH 5.2. Microshoots from explants of TC-stock plants also rooted more readily. Microshoot rootability decreased after 18 weeks on medium containing 68.6 μmol (12 mg/liter) 2iP. Microshoot production and rootability increased after 3 additional weeks on Zimm medium without 2iP present. Leaf-bud cuttings of ‘Northblue’ TC-stock plants treated with 5% and 10% concentrations of a commercial rooting compound (Dip-n-Grow) had a slightly higher rooting percentage and root rating than nontreated cuttings from ST-stock plants. However, cuttings from ST-stock plants of the same age showed larger increases in root formation and percentage of rooting in response to the same rooting compound treatments. Leaf-bud cuttings from vegetative TC-stock plants that developed shoots had more basal branches than those from floral ST-stock plants. Branch elongation was greatest and basal branches fewest on cuttings from floral ST stock plants. Successful propagation with cuttings and in vitro explants may be related to the condition of the stock plants, which have been altered by their own propagation methods and the plant growth regulators applied. Chemical names used: 1H-indole-3-acetic acid (IAA); 1H-indole-3-butanoic acid (IBA); 1-naphthaleneacetic acid (NAA); N-(3-methyl-2-butenyl)-2H-purin-6-amine (2iP).