Mycorrhizal Fungi in Rooting Substrate Influences the Quantity and Quality of Roots on Stem Cuttings of Hick's Yew

In a commercial nursery propagation system for hick’s yew (Taxus ×media ‘Hicksii’), we assessed whether or not the addition of inoculum of the vesicular–arbuscular mycorrhizal fungus (VAMF) Glomus intraradices into the rooting substrate during cutting propagation increased rooting, and how the quantity of inoculum influenced rooting. At 15 and 22 weeks (108 and 156 d) after cuttings were treated with root hormones and stuck, root initiation was higher on cuttings stuck in the rooting substrate containing VAMF inoculum. Increasing the quantity of inoculum in the rooting substrate increased root growth during the early stages of rooting. However the highest level of inoculum tested increased adventitious root initiation without increased root growth. Our results indicate that if VAMF inoculum is used during propagation from cuttings, there are optimal levels required to alter the initiation and growth of roots. For hick’s yew, 1:100 or 2:100 (by volume) rates of G. intraradices in the rooting substrate increased the number of primary roots and growth of adventitious roots on cuttings above that achieved by using rooting hormone alone.