Physical environment in vitro affects laboratory and nursery growth of micropropagated hostas

Hosta x hybrid Tratt. 'Blue Cadet' and Hosta tokudama Tratt. 'Newberry Gold' were micropropagated in shaken liquid culture and on agar media, in conventional vessels and vessels modified for ventilation in vitro. Acclimatization under intermittent mist and growth in an outdoor nursery during the late spring and summer were monitored by dry weight analysis of sample plants every 4 days for a 60-day period (ex vitro growth). Results for 'Newberry Gold' were 1) in vitro shoot growth was greater in liquid than agar culture, regardless of vessel; 2) shoots from agar or liquid culture grew at similar rates ex vitro; 3) ex vitro root growth was greater for liquid than agar cultured plants, regardless of vessel type. Results for 'Blue Cadet' were 1) in vitro and ex vitro shoot growth was greater in liquid than agar culture regardless of vessel type and 2) ex vitro root growth was greatest for liquid cultured plants from conventional vessels. Ventilated vessels were generally beneficial for agar but not liquid culture. Benefits of liquid culture for micropropagation of Hosta found in vitro are at least maintained and sometimes enhanced during ex vitro growth in the mist bed and nursery.