In vitro adventitious rooting of Cornus florida microshoots

Cornus florida L. (flowering dogwood) has been successfully micropropagated, but low rooting of microshoots makes the system inefficient. This study was conducted to increase rooting efficiency of flowering dogwood microshoots over that previously achieved. Microshoots originating from acclimatized axillary and nodal bud stock cultures were excised and treated with different concentrations and combinations of various auxins including indole-3-acetic acid (IAA), 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA). Effect of microshoot age on rooting efficiency was also examined. Of the auxins tested, maximum rooting was observed with 4.4 μM IBA. The age of microshoot explants had a significant effect on rooting. Five to seven-week-old microshoots treated continuously with 4.9 μM IBA in Woody plant medium (WPM) consistently had the best and most consistent rooting efficiency (about 83%).