Abstract
Micropropagation of Hexastylis species (Aristolochiaceae) requires the development of establishment protocols for in vitro-generated microcuttings. Hexastylis shuttleworthii (Britten & Baker f.) Small var. harperi Gaddy in vitro-rooted microcuttings survived in higher percentages (67%) and had more leaves after 7.5 mo than ex vitro-rooted microcuttings (8%); however, once rooted, both survived equally under greenhouse conditions. In vitro-rooted microcuttings of H. arifolia (Michx.) Small var. arifolia, H. minor (Ashe) Blomquist, and H. speciosa Harper ‘Buxom Beauty’ cultured for 4 wk with IBA (0, 2.5, 5, or 10 μM) survived transplanting equally well. A blended Metro-Mix 510:perlite mix (1:1, v:v) improved greenhouse survival of in vitro-rooted microcuttings of H. arifolia and H. speciosa ‘Buxom Beauty’ compared to Metro-Mix 510 alone. Higher percentages of H. shuttleworthii var. harperi multiple-crown microcuttings survived (96%) compared to single-crown microcuttings (29%), but after one year, neither initial crown number nor first-year overwintering environment (greenhouse versus raised-field bed) affected growth. For H. naniflora (Blomquist) Pfeifer ‘Eco Décor’, initial in vitro-rooted microcutting fresh weight and leaf number failed to relate to survival (> 90%); however, initial fresh weight and root number were directly correlated with final plant size and leaf number after 14 mo in a raised-field bed. In vitro-rooted microcuttings of H. shuttleworthii var. harperi and H. naniflora ‘Eco Décor’ were readily established (> 86% survival) when planted directly in a raised-field bed under shade. Commercial micropropagation of Hexastylis species appears to be practical due to the ease with which in vitro-rooted microcuttings could be established ex vitro.
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