Hardwood Cutting Propagation of Confederate Rose Using Auxin and Wounding Treatments

Abstract

Confederate rose (Hibiscus mutabilis), a native of southeastern China, is an old-fashioned, ornamental plant often found in older gardens in the southern United States. Current breeding programs aim at developing selections with improved garden performance, thus providing new cultivars for nursery production. Hardy in U.S. Department of Agriculture (USDA) zones 7 to 9, plants grow as large shrubs or small trees in warmer areas, but generally die back to a woody base or short trunk in colder areas of their range. Stems from the past growing season that remain on plants during the winter in the warmer regions may be used to prepare hardwood stem cuttings. The current study examined hardwood cutting propagation of confederate rose in response to a 1-second basal quick-dip in auxin [1000 ppm indole-3-butyric acid (IBA), 3000 ppm IBA, 1000 ppm IBA + 500 ppm 1-naphthaleneacetic acid (NAA), and 3000 ppm IBA + 1500 ppm NAA] and a basal wound (along with 1000 ppm IBA only). Cuttings were rooted in a warm, high-humidity environment within a greenhouse. Auxin treatments improved overall rooting percentage and total root length, with 1000 ppm IBA (without and with a basal wound) providing the highest rooting percentages (about 70%) and nontreated cuttings the lowest (44%). A significant increase in total root length on rooted cuttings resulted with the use of 3000 ppm IBA (211 cm) and use of a basal wound plus 1000 ppm IBA (193 cm) compared with nontreated cuttings (87 cm). Auxin and wounding treatments did not have any significant inhibitory effects on budbreak and growth of new shoots on rooted cuttings.