Influence of dicamba and casein hydrolysate on somatic embryo number and culture quality in cell suspensions of Dactylis glomerata (Gramineae)

The effects of various concentrations and combinations of dicamba (3,6-dichloro-o-anisic acid) and casein hydrolysate on growth, mucilage accumulation, somatic embryo and root development in suspension cultures of Dactylis glomerata L. (orchardgrass) were examined. Fresh weight of culture tissue was increased with 20 M but not with 80 or 160 M dicamba in treatments with 1–4 g/l casein hydrolysate. Different casein hydrolysate concentrations did not alter the amount of mucilage (measured by viscosity) in the supernatant in the absence of dicamba. However, the addition of dicamba increased viscosity with 80 M giving the maximum response. Casein hydrolysate produced the greatest viscosity at 1–3 g/l in treatments where dicamba was present. Both dicamba and casein hydrolysate were required for development of somatic embryos. Dicamba at 40 M with 3–4 g/l casein hydrolysate produced approximately 2000 embryos/35 ml of suspension. Root development was inhibited by dicamba and stimulated by the presence of casein hydrolysate. The usefulness of medium component manipulations for influencing somatic embryogenesis and culture quality is discussed.