The Influence of Media with Different Nutrient Salt Concentrations on the Micropropagation of Hydrangea quercifolia Bartr. and Tagetes erecta L.

As an alternative to testing nutrient components separately, four common media formulations were used: Murashige and Skoog (MS), Driver and Kuniyuki (DKW), woody plant medium (WPM) and Anderson\u27s revised medium (AND). Each medium was tested separately. Then high salts formulation (MS and DKW) were mixed with low salts formulation (WPM and AND) at a half and half concentration. In total, eight different media were tested spanning high, intermediate and low nutrient salts concentrations. To test the media two different plant species were chosen, a woody species Hydrangea quercifolia (oakleaf hydrangea) and an herbaceous species Tagetes erecta (African marigold). Nodal explants were harvested from H. quercifolia `Dayspring\u27 stock plants grown in raised beds in a greenhouse. After being disinfested, explants were placed on the eight treatment media, along with 1.0 µM benzyladenine (BA) and 1.0 µM indolebutryic acid (IBA). In addition to the plant growth regulators (PGR\u27s), 10 ppm Orthene insecticide and 150 ppm Benlate fungicide were included in the tested media to prevent contamination from a spider mite infestation. Explants placed on WPM were significantly different than explants on other media. WPM explants initiated growth the most, but elongation was sluggish and leaves showed signs of deficiencies after 8 to 10 weeks in vitro. Intermediate salts media DKW/WPM and DKW/AND had fewer explants initiate growth then explants on WPM, but the few that did elongated. These explants had the maximum lengths of any other explant on all other treatments. Tagetes erecta `Marvel Orange\u27 seeds were sown in polyethylene flats in a lab under cool white fluorescent lamps. After about a month apical shoot tips were harvested, surface disinfested, and placed in vitro on the eight treatment media, with the same PGR\u27s and additives as the hydrangea experiment. Tagetes explants responded substantially faster than the Hydrangea explants, with growth initiating on all treatments within a week. Initially there were significant differences between treatments, but after 3 months in vitro there were no differences between treatments. Although no data was taken, there was observed differences between the treatment media. Explants on low salts media of WPM and AND show signs of nutrient deficiencies, with high salt media showed no deficiencies. Overall the best growth of axillary shoots was seen on high salt media of MS and DKW