Asexual Propagation by Stem Cuttings of Half-high and Low-bush Blueberries in Soilless Substrates

Two experiments evaluated rooting of blueberry in substrates for use in soilless production systems. Apical and basal semi-hardwood stem cuttings of Vaccinium corymbosum x angustifolium ‘Northland' were rooted in rockwool cubes, shredded rockwool, or 3 perlite:1 sphagnum peat moss (v/v). Cuttings were treated with 0.1% indolebutyric acid (IBA) in 1:1 95% ethyl alcohol: water, 0.1% potassium salt of indolebutyric acid (K-IBA), 1:1 95% ethyl alcohol: water, or water. In Expt. 2, basal stem cuttings of ‘Northland' and V. angustifolium ‘Brunswick' were rooted in the same substrates with the addition of coco coir, treated with 1,000 ppm K-IBA, then fertilized weekly (after rooting began) with water, 75 ppm N from 16-4-17 fertilizer or 4-18-38 and Ca(NO3)2 plus MgSO4 fertilizer, all adjusted to pH 4.0. Rooting percentages were calculated, and rooting quality was assessed using a 6-point visual scale. ‘Northland' roots well (>80%) in peat:perlite and coco coir substrates and acceptably in two rockwool substrates (∼50%). ‘Brunswick' rooted acceptably in peat:perlite and coco coir (27% and 41%, respectively), and very poorly in two rockwool substrates (<2%). Rooting of ‘Northland' was not improved with application of 0.1% auxin. Apical cuttings of ‘Northland' had a higher rooting success than basal stem cuttings. Weekly fertilization did not improve root ratings, and had minimal effect on rooting success. Index words: adventitious rooting, auxin, coco coir, hydroponics, indolebutyric acid, rockwool, Vaccinium. Species used: ‘Northland' half-highbush blueberry, Vaccinium corymbosum L. X angustifolium Aiton, ‘Brunswick' low-bush blueberry, V. angustifolium Aiton. Chemicals used: auxin, potassium salt indolebutyric acid, K-IBA; Sigma-Aldrich, St. Louis, MO, USA, auxin, indolebutyric acid, IBA; Sigma-Aldrich, St. Louis, MO, USA, Oasis® 16-4-17 fertilizer, OASIS® Grower Solutions, Kent, OH, USA, ChemGro 4-18-38 fertilizer, ChemGro Hydro-Gardens, Colorado Springs, CO, USA, Ca(NO3)2, Yara North America, Tampa, FL, USA, and MgSO4, PQ Corp., Valley Forge, PA, USA.