2017 ASHS Annual Conference

Substrates used in the propagation of herbaceous plants via cuttings are selected to provide a suitable environment for root growth. Biochar may have promise as a component in these substrates. My objective in this study was to assess the rooting of herbaceous cuttings in substrates containing biochar. I obtained cuttings of seven herbaceous perennial plants [Achillea L. hybrid, Ajuga reptans L., Coreopsis verticillata L., Iberis sempervirens L., Leucanthemum ×superbum (Bergmans ex J.W. Ingram) D.H. Kent, Phlox subulata L., and Salvia ×sylvestris L.] from commercial suppliers. I stuck the cuttings in a base substrate of 1:2 (v/v) Sphagnum peat and coarse perlite or the base substrate amended with biochar at 5 levels (0%, 10%, 20%, 40%, or 80%; v/v). The biochar was obtained from a commercial supplier and was screened to a maximum particle size of 6 mm prior to incorporation. Each cutting was stuck in a square rose pot (top width: 2.25 inches, depth: 3.25 inches, vol: 185 cm³). I treated each species as a separate randomized complete block design. The cuttings were placed under intermittent mist, with bottom heat supplied. There were 15 replicates in 2015 and 10 replicates in 2016. Data were collected after the recommended rooting period for the crop. I removed cuttings from containers, washed the roots, and assigned each cutting an Adventitious Rooting Rating (0 = cutting dead, 1 = cutting alive but no root development, 2 = minimal root development, 3 = moderate root development but insufficient for transplanting, 4 = good root development and sufficient for transplanting, 5 = optimal root development). Roots were excised from the stem and scanned with a flatbed scanner (Epson Perfection V19). Scans were analyzed for first order lateral root counts, total primary root length, and two-dimensional root area with ImageJ. Biochar inclusion rates of 0%, 10%, and 20% had no effect or a slightly positive effect on adventitious root development. The highest rates of biochar, 40% and 80%, resulted in no effect or a negative effect on root area, rating, and root length. In the 80% biochar substrate, root architecture frequently featured many short primary roots compared to the other substrates in the study, which had long primary roots. The results of this study suggest biochar may be safely used in cutting propagation substrates; however, for some species, use of substrates containing 80% biochar may increase the number of primary roots, but reduce primary root length.