Cultivar Specific Effects of Mycorrhizal Fungi on the Rooting of Miniature Rose Cuttings

Abstract

Abstract The benefits from root colonization by mycorrhizal fungi are thought to be highest when colonization occurs as early as possible during plant growth. We assessed whether addition of VA mycorrhizal fungi (VAMF) inoculum into rooting medium during cutting propagation would increase the quantity of rooting and the quality of rooted cuttings for five different cultivars of miniature roses (Rosa spp.). Four weeks after cuttings were stuck, the number of cuttings with roots for two cultivars that normally take longer to root, increased with addition of VAMF inoculum into the rooting medium. The combination of hormone treatment (IBA and NAA) and VAMF inoculum in the rooting medium increased the number of rooted cuttings and the number of roots per cutting for three cultivars when compared to cuttings that only received hormone treatment. Increases in root initiation and root growth of cuttings rooted in medium containing VAMF inoculum were not always associated with increased levels of root colonization by VAM fungi. Our results indicate that although adding VAMF inoculum into the rooting medium does not always increase root initiation, in some cultivars the combination of VAMF inoculum and rooting hormones can increase root initiation and potentially increase the quality of rooted cutting produced.