Softwood terminal stem cuttings were collected at two developmental stages from twenty mature trees of Amur maackia (Maackia amurensis Rupr. and Maxim) growing in Minnesota, Maryland, and Washington DC. Cuttings were treated with either 0 or 2500 ppm (0.25%) of a potassium salt formulation of indole-3-butyric acid (K-IBA) and stuck under intermittent mist with bottom-heat. Cuttings were evaluated for rooting after 12 weeks. Cutting collection date did not affect rooting of most genotypes. Treatment with K-IBA nominally improved root rating scores and root numbers. All trees exhibited the capacity for rooting with individual rooting percentages ranging from 19% to 92%. Based upon mean visual ratings, cuttings from 14 of the 20 trees produced root systems of acceptable quality. These findings indicate that mature Maackia amurensis trees can be propagated by softwood cuttings, but refinement of the rooting protocol may be required to achieve acceptable levels of rooting for some genotypes.
Journal Series Paper No. 20925 of the Minnesota Agricultural Experiment Station. Journal Paper No. J-15657 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011.
2Scientist. University of Minnesota Landscape Arboretum, Chanhassen, MN 55317.
3Assistant Professor. Department of Horticulture, Iowa State University, Ames, IA 50011
4Professor. University of Minnesota Landscape Arboretum, Chanhassen, MN 55317.