Influence of Rhizome Propagule Size on Yields and Triterpene Glycoside Concentrations of Black Cohosh [Actaea racemosa L. syn Cimicifuga racemosa (L.) Nuttal

Abstract

Black cohosh [Actaea racemosa L. syn. Cimicifuga racemosa (L.) Nuttal] is a native North American medicinal plant traditionally harvested for its rhizomes and roots. Black cohosh products were listed in the top 10 selling herbal supplements from 2002 to 2005. As a result of increasing commercial demand, there is a need to develop propagation protocols suitable for production purposes to replace current methods of harvesting from wild populations. The objectives of this study were to 1) determine optimal rhizome propagule division size for successful regeneration, 2) analyze triterpene glycoside concentrations, 3) quantify survival rates after 3 years of production, and 4) evaluate net yield results. Experimental sites included a shade cloth structure in an agricultural research field, a shaded forest interior, and a shaded, disturbed forest edge. Plant emergence, growth, and survival were assessed at each site over a 3-year period. Optimal rhizome division size for propagation was a 10 to 30-g section originating from terminal rhizome portions. Rhizome survival averaged 97% among all treatments tested by year 3 at three sites. No differences in mean triterpene glycoside concentrations were detected between rhizome size classes or sites tested. Mean cimiracemoside concentrations ranged from 0.80 to 1.39 mg·g–1 d/w tissue, deoxyactein 0.47 to 0.92 mg·g–1, and actein 10.41 to 13.69 mg·g–1. No differences in triterpene levels were detected between flowering and nonflowering plants, nor were yields reduced. Net yields from a shade cloth production site were 9 and 17 times higher than a disturbed forest edge and forest site respectively. Black cohosh is a strong candidate for commercial propagation under adequate site selection.