Micropropagation of Baptisia `Purple Smoke'

Abstract

Shoot explants from actively growing, greenhouse-maintained plants of Baptisia `Purple Smoke' were cultured in vitro for shoot initiation on Murashige and Skoog (MS) basal medium containing vitamins and supplemented with 30 g·L–1 sucrose, 8.87 μm BA, and 4.14 μm K-IBA. All subsequent media were supplemented with 2.47 mm NaH2PO4 to enhance shoot growth. Single-node explants were subcultured for shoot multiplication on MS medium with either no plant growth regulator or with 2.22, 4.44, 8.87, 17.74, or 35.48 mm BA in combination with 0.0 or 4.14 μm K-IBA. Explants produced a maximum of 4.1 shoots on the medium with 2.22 μm BA. Shoots rooted on all concentrations of K-IBA (2.07, 4.14, 10.36, or 20.72 μm) and K-NAA (2.23, 4.46, 11.15, or 22.29 μm) tested. Maximum rooting was 100% on MS medium with 11.15 μm K-NAA; however, this treatment induced copious stem callusing. Rooted shoots were greenhouse-acclimatized for 2.5 weeks. Overall survival was 86%. For optimal rooting and subsequent acclimatization, treatment with 2.23 μm K-NAA is recommended; this resulted in 83% rooting and 87% acclimatization. Chemical names used: N6 benzyladenine (BA); potassium salt of indole-3-butyric acid (K-IBA); potassium salt of 1-naphthalene acetic acid (K-NAA).