Adventitious rooting in apple rootstock MM.106: Effects of arbuscular mycorrhizal fungi (AMF) and plant growth regulators

To assess the efficacy of arbuscular mycorrhizal fungi (AMP) for improving the rooting and growth of hardwood cuttings of apple rootstock MM.106, three mycorrhizal species (Sclerocystis dussi, Glomus intraradices, and G. fasciculatum) were tested. Rootstock cuttings from each AMP inoculation treatment were then treated, or not treated, with the rooting hormone, indole 3-butyric acid (IBA), or a rooting inhibitor, cinnamic acid (CA) each at 2.5 g l(-1). Cuttings that had not been inoculated with AMF or treated with either growth regulator served as controls. The results indicated that, after 90 d, cuttings inoculated with any of the three AMF alone, or in combination with 2.5 g l(-1) IBA had significantly higher percentages of rooting and growth than the untreated controls. The combined application of AMP plus 2.5 g l(-1) CA also improved the rooting percentage, which was significantly higher than in the untreated controls. Thus, the positive response to AMF inoculation was further improved when combined with 2.5 g l(-1) IBA.