Optimizing Root Formation for in Vitro Chokecherry (Prunus virginiana)

Chokecherry (Prunus virginiana L.) is a native North American plant that has potential as a regionally important alternative fruit crop.  Several fruiting types have been selected but are proving difficult to propagate.  These selections are growing successfully in stage II tissue culture, but ex vitro establishment has been problematic.  Plantlets were subjected to one of a combination of in vitro and ex vitro conditioning treatments including short and prolonged exposure to auxins (3 mg/L NAA or 3 mg/L IBA) or etiolation, and then evaluated for root formation and ex vitro survival.  Plantlets transferred directly from stage II media to potting soil and placed under intermittent mist had an establishment rate of 40.6%.  Hormone treatments and etiolation both resulted in reduced establishment and survival.  Interestingly, some plantlets left on stage II media without transferring to fresh media for 12 to 15 weeks showed rooting percentages of 47.2%.  More work is needed to increase rooting percentage and initial survival in order for clonal propagation of these fruiting chokecherry selections to be commercially viable.