Rapidin VitroRooting of the Apple Rootstock M.9

SummaryThe apple rootstock M.9 is difficult to root by conventional propagation procedures but more than 60% rooting was readily achieved by in vitro techniques. Successful rooting was related to exposure of shoot cultures to hormone-containing media for only four days followed by transfer to hormone-free media. This procedure prevented callus formation and led to a three-fold increase in root number per rooted culture compared to continuous contact with hormones. A synergistic effect of IBA and phloroglucinol on rooting was observed irrespective of whether the transfer to hormone-free media was made.