Effects of Rooting Agents and Shading Treatments on Rooting and Growth of Highbush Blueberry Hardwood Cuttings

Abstract

Rooting agents and shading treatments were tested in two different experiments to determine their effects on the establishment success of hardwood cuttings of three highbush blueberry varieties ‘Bluecrop’, ‘Duke’ and ‘Sunrise’. For the experiment with rooting agents, one-cm long bases of the cuttings were dipped into solutions of IBA or NAA for 5 s, both at 0, 500 and 1000 mg · L ?1 in 50% ethanol, and were also treated with Rootone® powder. Determined 90 days after cutting, the percent rooting and root weight were increased by NAA at 500 mg · L ?1 in ‘Bluecrop’ and ‘Sunrise’, while in ‘Duke’ IBA at 500 mg · L ?1 was effective. These auxin treatments were found to work better than a commercial product Rootone®. The rooting agent-induced increases in root development resulted in better shoot growth of the cuttings in all three varieties, as determined after 90 days of further growth in individual containers. In the experiment with shading treatments, different levels of the shading treatment (30 to 90%) were imposed over the cutting bed under no mist. In all three varieties, 30% shading increased the percent rooting and root and shoot growth, compared to no shading control. However, shading levels higher than 50% shading were found to be inhibitory for hardwood cuttings of highbush blueberries, especially under the environmental conditions with no mist system.