2019 ASHS Annual Conference

Hardy begonia (Begonia grandis subsp. evansiana) is one of the tuber-producing begonia species and is the only frost-hardy begonia (USDA Zone 6). Hardy begonia has received a revival in popularity as a shade-tolerant, summer flowering perennial. It apparently survives winter temperatures as basal or dispersed aerial tubers. Aerial tubers form late in the summer under short daylengths. There is limited information on the propagation of hardy begonia related to seed or tuber propagation. Hardy begonia flowers in late summer and fruits often do not reach full maturity before frost. Seed harvested from swollen fruits following petal abscission were collected and dried under ambient lab conditions. Seed harvested from dried capsules collected from fruit prior to observable natural desiccation had a mixture of filled and unfilled seeds and filled seeds from these fruits germinated slowly (>two weeks). Seed harvested from dried capsules collected from fruit showing some observable natural desiccation had a higher percentage of filled seeds and these seeds germinated in less than one week. Aerial tubers form in leaf axils and tuber size varied based on node location on the plant. Tubers of various sizes were placed in a petri dish with vermiculite and placed at 10C for 0 to 10 weeks. Tubers did not form plants without a chilling treatment. Plant formation began after four weeks of chilling, but the highest plantlet formation occurred after six and ten weeks of chilling. There was no difference observed based on tuber size, but larger tubers produced larger plantlets. Tubers showed polar development with shoots forming only at the apical end of the tuber. In vitro shoot cultures were established for seeds, tubers and tuber-derived shoots. In initial studies, cultures derived from seedlings produced the most vigorous cultures. Studies are ongoing to investigate the cultural parameters (cytokinin, sugar concentration, photoperiod) that support in vitro tuber induction.