Potassium salt of 1-naphthaleneacetic acid promotes rhizogenesis in Amsonia elliptica stem cuttings

Amsonia elliptica is valued for its medicinal and ornamental potential. However, it is listed as an endangered species in South Korea due to overharvesting and habitat destruction. This study aimed to develop an efficient protocol for mass vegetative propagation of A. elliptica using stem cuttings. We tested Rootone (0.4 % 1-naphthylacetic acid) and potassium salts of indole-3-butyric acid (K-IBA) and 1-naphthaleneacetic acid (K-NAA) applied via basal dip or foliar spray. After six weeks, cuttings treated with 2000 mg L⁻¹K-NAA showed the best rooting traits, with 93.3 % rooting, 17.5 roots per cutting, and 55.4 mm root length, along with the highest fresh (92.9 mg) and dry root mass (8.8 mg). Dipping cuttings in 2000 mg L⁻¹K-NAA for 1 min is recommended as the most effective treatment for large-scale propagation of A. elliptica. This optimized propagation method will facilitate the conservation and ornamental use of A. elliptica.