Defining a Protocol for Vegetative Propagation of Baptisia, Eupatorium and Thermopsis

Abstract

We determined that highly successful vegetative propagation is possible for Baptisia, Thermopsis and Eupatorium. This is significant because vegetative propagation of these native genera has not been widely practiced in commercial ornamental production. Seed propagation has been utilized over vegetative propagation due to historically low rooting percentages and reduced crowning (bud formation at the root-shoot union) when vegetative propagation is employed. However, vegetative propagation can enable the production of ornamental nursery stock quicker and with greater uniformity in finishing time compared to seed propagation. Vegetative propagation can also facilitate the perpetuation of threatened or endangered species that have small or isolated populations (limited sexual reproduction) or can be used to build numbers of phenotypically superior individuals without wild digging. Four model species representing three native herbaceous genera that include multiple threatened or endangered species were used in the study. Four concentrations of K-IBA (potassium salt of Indole-3-butyric acid) were examined along with 28 and 56 days in a propagation environment to determine the best rooting percentage and root quality for each species. An economic analysis was conducted to test the efficacy of treatment with K-IBA versus double-sticking two untreated cuttings. In addition to developing a commercially viable propagation protocol for these three species, we also determined that treatment with K-IBA is not necessary for successful propagation of the majority of these species, but that more time in a commercial propagation environment leads to higher rooting percentages at a reduced propagation cost.