A Revised Tissue Culture Medium for Shoot Multiplication of Rhododendron

Revision of the Murashige-Skoog (MS) 1962 inorganic formula was necessary for the successful culture of rhododendron cultivars. A bioassay system was developed to assess the effects of modifying the MS formula. Inorganic revisions included reduction of nitrogen from 60 to 14.7 m m and potassium from 20 to 4.7 m m . Phosphorus was adjusted to 2.75 m m . Iron concentration was doubled to 200 μ m and iodine was reduced to 1.8 μ m . These changes reduced the salinity of the inorganics from 5.2 to 2.2 mmho cm −1 . General growth regulator concentrations for shoot proliferation are 1 mg/liter 3-aceticindole acid (I A A) and 5 mg/liter N 6 -(2-isopentenyl)-adenine (2iP), but these concentrations vary among cultivars.