Rooting Efficiency of Amur Maple Seedless Selections Produced by Mutagenesis1

Amur maple (Acer ginnala Maxim.) is a widely planted small tree with attractive red fall foliage. In many states, it is classified as a noxious weed and regulations restrict propagation and sale, limiting customer choice. Stem cuttings are commonly used as a means of asexual propagation of Amur maple, with softwood cuttings being the easiest to root. Here we report adventitious rooting efficiency of seedless Amur maple selections using four indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and four naphthalene acetic acid (NAA; 100, 500, 1,500, 5,000 ppm) treatments and a no hormone control. Overall, cuttings treated with 5,000 or 10,000 ppm IBA and 5,000 ppm NAA resulted in the highest percent rooting (PR), mean number of roots (MNR), and mean length of the longest root (MRL) across all seedless selections. Seedless selections SW-30-14 and SW-30-130 had the highest PR, 66% and 67%, respectively, and will perform well in commercial propagation. This level of rooting was greater than that of the cultivar ‘Bailey Compact’ that had 46% PR, and the seedless selection SW-30-159 that had the lowest PR (10.3%), MNR (0.3), and MRL (0.2 in) averaged across all treatments. Cuttings from 4 of the 5 seedless selections treated with 1,500 ppm NAA had the greatest PR, whereas ‘Bailey Compact’ and SW-30-159 had the greatest PR with 5,000 ppm NAA. Results indicate that rooting efficiency was impacted by mutagenesis in some selections, which may require optimization of propagation methods for those selections. Index words: adventitious rooting, auxin, vegetative propagation, sterile, non-native invasive. Species used in this study: Amur maple (Acer ginnala Maxim.). Chemicals used in this study: indole-3-butyric acid (IBA; 500, 1,500, 5,000, 10,000 ppm) and naphthalene acetic acid (NAA; 100, 500, 1,500, 5,000 ppm). Significance to the Horticulture Industry This is an ongoing project researching mutagenesis breeding of Amur maple to reduce seed production and invasiveness. Amur maple is classified as a noxious or invasive plant and regulations restrict propagation and sale of this plant limiting customer choice. The seedless selections were used to conduct this rooting experiment. Commercialization of seedless Amur maple selections requires the development of a suitable asexual propagation method; therefore, a rooting experiment was performed. Seedless selections of Amur maple produced through mutagenesis respond differently to growth hormone treatments and levels and the majority of the selections can be efficiently propagated.