Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2000
Publication Date: 3/1/2001
Citation: Scagel, C.F. 2001. Cultivar specific effects of mycorrhizal fungi on the rooting of miniture rose cuttings. Journal of Environmental Horticulture. 19:15-20.
Interpretive Summary: 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 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.
Technical Abstract: Although commercially produced inoculum of VA mycorrhizal fungi (VAMF) is readily available to horticulturalists, cultivar specific responses to inoculation, and the optimal time for using inoculum during vegetative propagation are unclear. Our results showed that addition of VAMF inoculum into the rooting medium of miniature roses increased the amount of rooted cuttings for cultivars that normally take longer to root and increased the number of roots and root growth on several cultivars. Increases in root initiation and growth in response to adding VAMF inoculum into the rooting medium can decrease the amount of time for cuttings to attain an adequate amount of roots for transplanting and increase the quality of rooted cutting obtained. Our results also showed that increases in root initiation and root growth on cuttings rooted in medium containing VAMF inoculum were not always associated with increased levels of root colonization by VAM fungi. The response of cuttings to VAMF inoculum may not solely be a resul of mycorrhizal fungi in the inoculum, but could be a result of coincidental inoculation with bacteria associated with the spores, root fragments, and carrier substrates in the VAMF inoculum. Cultivar specific responses to adding VAMF inoculum into the rooting media suggests that combinations of cultivars, hormone applications, and VAMF inocula should be tested on different cultivars of plants before VAMF inoculum is used on a large scale across all cultivars of a crop.